Vol. 4 December 2016 RADIOLOGY & IMAGING

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1 Vol. 4 December 2016 RADIOLOGY & IMAGING 1

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9 content Ultrasound o1 Post Menopausal Bleeding & Retroverted uterus is TRUS value added tool to TAS Md Ameen MD, A.Arun Dilip, MD o2 Correlation CEUS & Sono elastography for malignant thyroid nodule evaluation Muthamil Malar DMRD, Md Ameen MD. PICTORIAL ESSAY o3 A Pictorial Essay Of Imaging -Vascular Anomalies Of Limbs Hye Sang MD, Tae min Lee MD, Yoo Jin Hong, Wong Jhu RADIOLOGY & IMAGING 9

10 TECHNICAL o4 Role Of Mr Elastography In 2016, New Prospective Approach To Other Advanced Sequences. Ujino K, Barnes ME, Cha SS, Langins AP, Bailey KR, Seward JB Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras at dolor vulputate, mollis nibh et, porta libero. 05 Recent Advances And Technique- Role Of Mr Urography In Modern Day Practise JR Basford MD, TR Jenkyn MD, KN Ane MD, RL Ehman MD, G Heers MD, KR Kaufman MD CT & MRI o6 Functional Mr Techniques Applications In Biological Effects Of Endometrial Carcinoma Md Ameen MD, Kumaran MD o7 128 Slice Multidetector Cardiac Ct Versus Echocardiography Correlation For Three Dimensional Volume Analysis Of Left Atrium Md Ameen MD, N.S.Mani MD CASE PRESENTATION o8 A Rare Case Of Hemangiopericytoma Of Lower Face & Neck CM Tempany MD, FA Masoud MD, FF Marshall MD 10 RADIOLOGY & IMAGING

11 case presentation o9 Case Presentation: Primary synovial osteochondromatosis of the ankle JW Walike MD, BJ Bailey MD 10 Primary hydatid cyst of brain: RF Browne MD, DJ Tuite MD. case presentation 11 Soft tissue myxoid sarcoma of elbow- A rare case report A Kohli MD, RK Gupta MD, H Poptani MD. 12 A complex fistula-in-ano presenting as a soft tissue tumor De Schepper AM, De Beuckeleer CASE PRESENTATION 13 A Rare case report of emphysematous cholecystitis with perforation without hemo/pneumoperitoneum. T Todorov MD, K Vutova MD, D Petkov MD RADIOLOGY & IMAGING 11

12 case presentation 14 Unusual case of dermoid cyst with right side pyosalpinx. G Girish MD, WK Choo MD, SK Morcos MD 12 RADIOLOGY & IMAGING

13 Post Menopausal Bleeding & Retroverted uterus is TRUS value added tool to TAS Md Ameen MD, A.Arun Dilip, MD ULTRASOUND DEPARTMENT OF RADIODIAGNOSIS, ACS Medical College, Periyar EVR high Road,NH-4, Chennai-Bangalore Highways, Velappanchavadi, Chennai , Tamilnadu, India Objective To report the value of transrectal ultrasonography in female reproductive tract in specific conditions like post menopausal bleeding and retroverted uterus as a complimentary problem solving technique after TAS & TVS Methods 21 cases are presented of women for whom trans rectal ultrasonography perfomed after TAS and optional TVS provided additional clinical information for better exploring the diagnosis. Results Trans rectal sonography was helpful in two scenarios (1) Women with retroverted uterus in whom endometrial stripe was virtually parallel to ultrasound beam and thus could not be properly measured in TAS & TVS (2) Post menopausal bleeding patient whom TVS cannot be done and TAS alone giving suboptimal results due to physiological inadequate bladder distension due to ageing. In 1 case, TRUS yielded diagnosis of mildly thickened endometrial stripe. Biopsy revealed atrophic changes without evidence of malignancy, in this case both TAS & TVS misleading as suspicious for endometrial hyperplasia / malignancy. Moreover in most of the patients with post menopausal bleeding, TVS cannot be done because of pain and bleeding- in this scenario TRUS definitely value added tool to TAS- widely underperformed around the world. Conclusions. TRUS of the female internal reproductive tract can provide clinically useful information to complement TAS & TVS in retroverted and post menopausal bleeding patients Keywords Transrectal sonography, trasabdominal sonography,transvaginal sonography, retroverted uterus & post menopausal bleeding Abbreviations TRUS- transrectal ultrasonography TVS-transvaginal ultrasonography TAS-trans abdominal ultrasonography RADIOLOGY & IMAGING 13

14 Introduction Trans vagnial ultrasonography (TVS) is unchallenged complimentary technique for imaging female internal reproductive tract in field of obstetrics & gyncecology and radio diagnosis till present date. Moreover TVS probe comes along as mandatory probe in all ultrasound clinic for diagnostic usage with superior resolution. Advantage of trans vagnial sonography ( TVS ) in field of early obstetrics being unquestionable after TAS. Advantage of TRUS in early pregnant patients, patient with suspected cervical incompetence and in virgins also mentioned widely in literature where TVS cannot be used 1 But the advantage of TRUS in specific female internal reproductive organs conditions like retroverted uterus and post menopausal bleeding from best of my knowledge & experience, from the literature not been reported. There is also certain limitations that sonologist unaware of fact, introitus is fulcrum for all TVS transducer angulatation, so freedom of angulation is limited. Moreover limitation of TVUS is particularly relevant if an intervening bowel loop or refractive interface impedes transmission of ultrasound beam to a region of interest located more deeply. Major lacunae of TVS in many women with retroverted uterus, in whom endometrial stripe is often aligned parallel to TVUS beam and thus cannot be imaged properly. There also patients in whom an important finding is not detected because the transducer position necessary to visualize it causes extreme patient discomfort 2 In a analogus fashion, we regard the rectum as a complementary window that can be used for problem solving after TVUS in selected cases in which difficulty arisen that might be overcome by scanning from a different vantage point. In our experience, TRUS has proved extremely useful as a complementary problem solving technique where TVUS cannot be deployed in retroverted uterus & post menopausal bleeding Materials & methods Study population consisted of 18 patients, TAS already done. Study population was approved by ethics committee of our hospital and patients informed consent was obtained. From January 2013 to september 2013, 18 patients with either retroverted uterus- TAS diagnosed & patients with post menopausal bleeding included as criteria in the study. Minimum age 25 years and maximum age 55 years. One experienced radiologist ( myself) of 11 years experience in field of sonology & imaging along with two experienced female sonographers covered the study group. USG machine deployed is GE voluson P5 colour Doppler unit with curvilinear transabdominal probe3.5 MHZ, TVS and TRUS done with same probe with variability of 7.5 to 11 MHZ adjustable with minimal alteration in technical parameters. The transducer is covered with fresh condom and inserted into rectum without prior bowel cleansing along with ultrasound jelly. After TAS done in supine position, patient asked to void the bladder and requested to turn in left lateral decubitus position for TRUS. TVS also optionally done before TRUS in retroverted uterus diagnosed patients in TAS. In post menopausal bleeding patients only TRUS done after TAS study. Total duration of study was between 3 to 10 minutes. None of patient complained of any pain or discomfort following procedure and all patients came as inpatient and selected randomly and procedure done. Out of 18 patients on immediate follow up, biopsy done for 11 patients following TRUS, in 3-5 days results also obtained Examinations were scored on a scale of 1-3 given for excellent ( 3), acceptable ( 2) and unacceptable ( 1) visualization of endo PATIENTS Excellent Acceptable Unacceptable Biopsy done Women age < 45 ( retroverted patients ) TRUS ( n=12) TAS ( n= 8) TVUS (n=10) yes ( n=12) Women age > 45 ( post menopausal Bleeding patients) TRUS ( n=6) TAS ( n= 5) 14 RADIOLOGY & IMAGING TAS (n=1) Yes ( n= 1) Table 1: Visualization of endometrial stripe in post menopausal and retroverted uterus

15 Figures 1 & 2: TAS and TRUS done simultaneously for post menopausal patients- thickened endometrium seen in TAS appears to show normal endometrial stripe in TRUS technique and also proved to be atrophied endometrium in biopsy study. Fig 1 metrial stripe in TAS, TVS versus TAS with exact measurement taken in all techniques ( TAS, TVS & TRUS) For statistical analysis the scans that were excellent and acceptable were grouped together and analysis done using fischer exact test. Results Two of the 18 patients excluded from the study due to failure to do biopsy follow up for confirmation of TRUS efficacy. Out of 18 patients 12 patients were retroverted uterus incidentally diagnosed in TAS and with other medical conditions admitted. 10 patients cooperated for biopsy follow up following TRUS. Two patients discharged upon short stay in hospital, biopsy follow up could not be done since patient consent not given. 6 patients admitted with pelvic bleeding post menopausal status, along with pelvic discomfort and pain. Biopsy done only for 1 patient due to bleeding and discomfort. Only TAS followed by TRUS done for all other 5 patients In our experience, out of 6 post menopausal bleeding patients, RADIOLOGY & IMAGING Fig 2 15

16 TRUS not only facilitate visualization of endometrial stripe and also adnexal structure which TVS cannot be done. Excellent visualization of all three layers of endometrial stripe obtained along with measurement. TRUS also showed excellent visualization even in TVUS done retroverted uterus cases, for distant adnexal structures not clearly made out from vagina in TVS study. Moreover TRUS technique in visualizing the endometrial stripe in retroverted uterus than in TAS & TVS is far superior in results as proved in biopsy. Discussion As illustrated, the value of adjunctive TRUS lies in its provision of an alternate scanning window in selected patients in whom TAS & TVUS is incomplete. This report introduces the use of TRUS as a complementary problem solving technique after TAS. In many instances in day to day practice, sonologically retroverted uterus difficult to visualize both in TAS & TVUS technique. As problem solving technique, TRUS helpful in visualizing the endometrial stripe in reproductive women and difficult visualizing adenexal structures in post menopausal woman in TAS & TVUS study also possible by TRUS TRUS in two patients of post menopausal patient, endometrial stripe seems to be misleading measuring ( 15 mm) diagnostic assumption of endometrial carcinoma made, but however advantage of TRUS complementary technique excluded diagnosis. Also proved in biopsy as atrophied endometrium in 1 patient. In our experience, most women will subsequently agree to TRUS after TAS and TVUS when clearly explained to them as added diagnostic technique. Only thing minimal patient discomfort associated with TRUS, we could have minimized by intra rectal administration of lidocaine gel before insertion of probe. Conclusion To summarize, TRUS for the female internal reproductive tract in specific conditions like post menopausal bleeding uterus and retroverted uterus can provide clinically useful information and to avoid false positive diagnosis to complement TAS & TVUS study technique. Conflict of interest The author declare no conflict of interest Acknowledgment We are grateful to ACS ultrasound senior staff and sonographers for secretarial assistance References 1. Lopez- Rasines G, Abascal F, Calabia A, Rico M, Cavero A. Trans rectal sonography in the assessment of vagnial pathology: a preliminary study. J Clin Ultrasound 1998; 26: Benaceraf BR. Filling of the bladder for pelvic sonograms: an ancient form of torture. Journal of ultrasound medicine 2003; 22: Nasri MN. Transvaginal versus transrectal sonography in post menopausal women.br J Obst Gynecol 1992; 99: Luna JA, Goldstein RB. Sonographic visualization of neonatal posterior fossa abnormalities through the posterolateral fontanelle. AJR Am J Roengenol 2000; 174: Chatruvedi P, Insana MF, Hall TJ. Ultrasonic and elasticity imaging to model disease induced changes in soft tissue structure. Med Imaging Anal 1998; 2: Timor-Tritsch IE, Monteagudo A, Rebarber A, Goldstein SR, Tsymbal T. Transrectal scanning: an alternative when transvagnial scanning is not feasible. Ultrasound Obstet Gynecol 2003; 21: RADIOLOGY & IMAGING

17 Correlation CEUS & Sono Elastography for Malignant Thyroid Nodule Evaluation N Kumaran MD, Md Ameen MD ULTRASOUND Department Of Radiodiagnosis, Velammal Teaching Hospital, Madural-Tuticorin Ring Road, Anupandi, Madurai ,Tamil Nadu, India Objective The aim was to study the patterns of solitary thyroid nodule with real time contrast enhanced ultrasound & sono elastography in establishing malignant thyroid nodule Materials & Methods 9 cases are presented ( 4 men & 5 women) for whom FNAC or CT neck with established nodal metastasis workup done. Degree of enhancement, process of enhancement, homogeneity of enhancement, surface of enhanced lesions versus strain & shear wave elastography Q box correlation done for solitary lesions. Results Contrast enhanced patterns significantly different for FNAC proved malignant or established higher staging primary in CT. The shape of most lesions in contrast ultrasound was irregular ( 94.59%), the boundary was however unclear ( 86.49%), inhomogenity ( 78.38%). Mean elasticity ratio varied with tumour grade and staging. Keywords Thyroid, contrast enhanced ultrasound, strain and shear wave elastography, enhancement characterstics, Q box and mean statistics elastography correlation, tumour grade. RADIOLOGY & IMAGING 17

18 Introduction Despite medical and socioeconomic advances in thyroid cancer screening for past 3 decades, thyroid cancer is one most commonly detected cancer for mortality mostly in men after women in India. Various literature discuss several factors that determine tumour prognosis like tumour size in ultrasound, CEUS ( contrast enahanced ultrasound), and elastography. Some of which include tumour size, morphology & internal characterstics. Currently FNAC however invasive method remains gold standard for confirming malignant thyroid nodule inspite of recent advances in thyroid sonography. Moreover last 1 decade, new sonographic technique elastography developed. This technique also determines lesion stiffness and standard mean value also given for malignat versus benign nodule differentiation. Studies also shown that elastography of thyroid has potential to differentiate benign and malignant thyroid lesions with higher sensitivity and specificity. In recent prospective study, shear elastography reported 99 % sensitivity and 87% specificity in differentiating benign versus malignant thyroid nodule lesions. In many reviews from literature, it was also noted tumour length on elastography to the length of the lesion on B mode imaging ( the elasticity imaging/ B mode ratio) was larger for aggressive tumours like anaplastic types. Previous studies have also demonstrated the feasibility of contrast enahcned ultrasonography ( CEUS) for differentiation of benign and malignant thyroid nodules. In one of the previous study, CEUS demonstrated sensitivity of 76.9%, specificity of 84.8% and accuracy of 82.6%. Quanantitative analysis of CEUS using micro bubble contrast agent allows the differentiation of benign and malignant thyroid nodules and may contribute and potentially serve, in addition to grey scale and Doppler ultrasound, as an adjunctive tool in assessment of patients with thyroid nodules. Horunung et al reported CEUS reported CEUS, a highly sensitive method for detection of microvascularization of thyroid carcinoma. There was also study reported that contrast enhancement ultrasound patterns were different in benign and malignant lesions. Ring enhancement predictive of beingn lesions, whereas heterogenous enhancement was helpful for detecting malignant lesions. There is certain limitations that even in present scenario, FNAC for confirming thyroid malignant remains gold standard- inspite of GRADES Degree Method Complete Boundary Shape PAPILLARY Significant Centri Complete Regular Regular FOLLICULAR Significant Concent Complete Regular Regular METASTASIS Very Significant Centrip Incomplete Irregular Irregular ANAPLASTIC Central Centri Incomplete Irregular Irregular Table 1: Difference of contrast enhacement patterns of malignant nodules 18 RADIOLOGY & IMAGING

19 above mentioned recent advances sonographic techniques. Major lacunae in present decades, still overdependent on FNAC inspite of recent advances in sonographic techniques. Our study focused on malignant thyroid nodules worked up patients by FNAC proved or CECT with known nodal spread- combined sonographic techniques of elastography and contrast enhanced ultrasound done to prove 100 % sensitivity and specificity in diagnosing & grading malignant nodules. Combined sonographic technique value added tool in detecting and grading malignant thyroid nodule with grey scale B mode ultrasound in future replacing FNAC. Moreover lacunae of FNAC for all the mass lesions of thyroid to be avoided. In best of my knowledge, FNAC contraindicated in bleeding disorders and thyroid AVM mass- prone for excessive bleeding. In our experience, combined elastography & contrast enahanced ultrasound has proved extremely useful as a detecting and grading problem solving technique for malignant thyroid nodule and replacement in future for invasive FNAC in new cases. Materials & methods RADIOLOGY & IMAGING Probability Papillary Follicular Anaplastic Metastasis Sensitivity Specificity PPV NPV Table 1: Combined diagnositv value of CEUS & sonoelastography technique Study population consisted of 19 patients, either FNAC or CT workup done and established malignant nodule. Retrospectively evaluated for thyroid malignant sensitivity by contrast enhanced ultrasound and strain & shear elastography. Study population was approved by ethics committee of our hospital and patients informed consent was obtained. From January 2016 to april 2016, 09 patients with inclusion criteria of known thyroid malignancy included in the study. Minimum age 25 years and maximum age 55 years. Two experienced radiologist ( myself) of 11 years experience in field of sonology & imaging along with two experienced female sonographers covered the study group. Moreover sonographers who prepared the patient for contrast ultrasonography were blinded. USG machine deployed is MINDRAY D5 colour Doppler unit with linear probe with frequency variability of 7.5 to 11 MHZ adjustable with minimal alteration in technical parameters. Initial thyroid nodule workup with done with non enhanced ultrasound. Patient neck was hyperextended and saggital & coronal planes nodule imaged.lesion characterstics, surface irregularity, size of the nodule, isthmus involvement & adjacent nodal involvement in cervical chain explored. Followed by Sonovue ( 25 mg) of lyophilized powder and 5 ml of 0.9% sodium chloride solution were configured into suspension, and mixed uniformly. Contrast injected through mostly brachial vein. The standard view of CEUS was the section which showed most abundant blood flow signals within the malignant nodule lesion by power Doppler.Focus was adjusted also to trailing edge of lesion, and the gain was adjusted to display only the boundaries of the lesion. During the investigation, Position of the probe was fixed and the patient was asked to avoid swallowing and breath holding. The real time dynamic images were stored in the ultrasonic instrument. Real time CEUS of thyroid nodule persist only 3 minutes. The contrast enhancement patterns of the lesions were assessed in following methods as follows 1. Degree of enhancement ( lower or higher to surrounding gland) 2. Method of enhancement ( centripetal enhancement or non concentric ( diffuse, eccentric) enhancement. 3.homogenous or inhomogenous type of enhancement. 4. Completeness of enhancement or incomplete 5. Boundary of enhanced lesions like ( blurred or well defined patterns) and regular After 15 minutes of CEUS done, sonoelastogram technique done for all the 9 patients. The displacement needed for obtaining elastogram was provided by the patient breathing or cardiac rebound. If required, minimal manual compression/ decompression was used to obtain the elastogram. Images were dis- 19

20 played side by side during a real time sonographic examination. Elasticity imaging/b-mode ratios were obtained by dividing the axis of maximum dimension on the B- mode image. Three measurements obtained from nodule of all patients, and the largest elasticity imaging/ B-mode ratio used.the highest ratio selected to the reflect point of maximum malignant potential in the thyroid nodule. A copy or shadow function was used to ensure that measurements were taken in the same location of the lesion. The greatest axis of maximum dimension of the lesion was measured on the B-mode image. Results Out of 9 patients, contrast enhancement pattern and elasticity/b-mode ratio dated calculated differs according to tumour aggressiveness and grades. FNAC out of 9 patients showed papillary - 4, follicular - 2 and meatstasis -2 and anaplatic in 1. Contrast enhacement pattern and sonoelastography results by statistical analysis were calculated by X2 test using statistical software SAS 8.0, taking P < 0.05 to be stastically significant difference. In our experience, diagnostic value of contrast enhancement patterns of malignant thyroid value differs in five aspects and sonoelastography ratio goes high in more aggressive malignant nodules. Moreover specificity when two techniques combined ( CEUS & sonoelastography) were extremely high with percentage of 94.3 % and 93.1 % respectively. Discussion Malignant nodules are the typical lesions which depend on blood vessels. Recently color Doppler and power Doppler have been most commonly used methods to detect blood vessels of tumour. Their larger blood vessels can be displayed by Doppler ultrasound, but micro vessels with low speed and flow cannot be shown. SonoVue is stabilized microbubble preparation containing sulfur hexafluoride with average diameter of 2.5 micrometre.microbubble can flow in the microcirculation and resonate at a low mechanical index. The microvascular perfusion of the tumour can be displayed clearly by using low energy Fig 1: CEUS patterns of enhancement without power Doppler Fig 2: Sonoelastography in compression technique for obtaining ratio in Q box Fig 3: CT workup in malignant thyroid nodule evaluation with nodal staging. 20 RADIOLOGY & IMAGING

21 acoustic emission and pulse inversion harmonic imaging. CEUS has made a major improvements in the diagnosis and differential diagnosis of thyroid nodule. CEUS clearly depicted morphology of enhancement by aggressive nature of malignant nodules can be divided into three grades for discussion Grade 1- low to moderate variety with homogenous enhancement, regular margin and complete enhancement of nodules ( follicular n=2, papillary n=2)fits into this grades Grade 2- moderate to high variety with inhomogenous enhacement, regular margin and 3/4th enhancement of nodules ( Papillary n=1, metastasis n=1) fit into this grades Grade 3- high degree of inhomogenous enhancement, irregular margin and incomplete enhancement of nodules ( metastasis n=1, anaplatic n=1) fit into this grades In sonoelastography technique elasticity / B mode ratios classified into two grades for discussion FNAC proved aggressive tumours like metastasis and anaplastic variety fits into more than 1 in elasticity/b mode ratio FNAC proved moderate infiltrating tumours variety fits into low score of less than 1 in elasticity/b mode ratio The study shown that combined CEUS and sonoelastography technique sensitivity and specificity of 94.3 % and 93.1 %. Conclusion The difference of contrast enchancement patterns of ma- RADIOLOGY & IMAGING lignant thyroid nodules in five aspects were significant such as degree of enhancement, homogeneity, completeness of enhancement, boundary of enhanced lesions. These contrast enhanced patterns contributed to the differential diagnosis of solitary malignant thyroid nodule. Likewise sonoelastography technique, elasticity/b mode ratio more than 1 and less than 1 corresponds to aggressive or moderate nature. By combining both advanced sonographic technique comprehensive diagnostic accuracy increased to higher level of sensitivity and specificity. In future role of FNAC in nodular thyroid lesion can become challenging as compared to present era where FNAC still gold standard. Conflict of interest The authors declare no conflict of interest Acknowledgment We are grateful to Velammal ultrasound senior staff and sonographers for secretarial assistance References 1. 1.Rago T, Santini F, Scutari M, Pinchera A, Vitti P. Elastography: new developments in ultrasound for predicting malignancy in thyroid nodule. J clin endocrinol metab 2007;92: Averkious M, Powers J, Skyna D, Bruce M, Jensen S. Ultrasound contrast imaging research. Ultrasound Q 2003;19: Mortensen JD, woolner LB, Bennett WA, Gross and microscopic findings in clinically normal thyroid glands. J Clin Endocrinol Metab 1955:15: Hegedius L. Clinical practice. The thyroid nodule. N Engl J Med 2004: 351: Zhang B, Jizang YX, Liu JB, Yang M, Dai Q, Zhu QL, et al. Utility of contrast enhanced ultrasound for evaluation of thyroid nodules. Thyroid 2010:20: Jain RK. Normalizing tumour vasculature with anti angiogenic therapy: A new paradigm for combination therapy. Nat Med 2001;7:

22 A pictorial essay of Imaging - Vascular anomalies of limbs Hye Sang MD, Tae min Lee MD, Yoo Jin Hong, Wong Jhu Abstract : Vascular anomalies, including vascular malformations and tumors, are frequently straightforward to detect; however, accurate diagnosis and appropriate treatment are often challenging. Misdiagnosis of these lesions can lead clinicians in the wrong direction when treating these patients, which can have unfavorable results. This review presents an overview of the classification systems that have been developed for the diagnosis of vascular lesions with a focus on the imaging characteristics. Pictorial examples of each lesion on physical examination, as well as non-invasive and minimally invasive imaging are presented. An overview of the endovascular treatment of these lesions is also given. In some cases, vascular anomalies may be associated with an underlying syndrome and several of the most commonly encountered syndromes are discussed. Understanding of the classification systems, familiarity with the treatment options and knowledge of the associated syndromes are essential for all physicians working with this patient population. The approach to the described entities necessitates an organized multi-disciplinary team effort, with diagnostic imaging playing an increasingly important role in the proper diagnosis and a combined interventional radiological and surgical results shows promising results. Key Words: Vascular malformation; Lymphatic malformation; Overgrowth syndromes; Arteriovenous malformation; Hemangioma Introduction: PICTORIAL ESSAY Anatomist and obstetrician William Hunter first described vascular anomalies in the mid-18th century in the context of iatrogenic creation of arteriovenous fistulas by phlebotomists[1]. Over the next century, description of these and more complex vascular lesions was furthered by the work of Dupuytren, Virchow, and others but the lack of a cohesive system of classification led to confusion, hampering further understanding of these entities. Since that time, categorization of these lesions has advanced from primitive descriptions and disorganized nomenclatures to a more a structured catalogue of classification. Mulliken and Glowacki pioneered this transformation[2], while the Hamburg classification system further refined it[3]. Early attempts at classification were based on the pathological appearance of the lesions without consideration for underlying biologic behavior. Terms such as erectile tumors, naevus maternus, and stigma metrocelis were applied without clear delineation[2]. It wasn t until 1982, when Mulliken and Glowacki introduced a classification system rooted in the pathophysiology of these lesions that much of the confusion surrounding these lesions was clarified[2]. This system divided vascular anomalies into two categories: vascular tumors (hemangiomas) and vascular malformations. This standard was adopted by the International Society for the Study of Vascular Anomalies (ISSVA)[3,4] and continues to be embraced by many clinicians in current practice. Subsequent modifications to this classification system have included the addition of other rare vascular tumors distinct from hemangiomas, including tufted angioma, Kaposiform hemangioendothelioma, angiosarcoma and others. With these additions, vascular anomalies continue to be divided into two categories: vascular tumors, which include hemangiomas, and vascular malformations. Several years later, the Hamburg classification system adopted an embryologic perspective to further aid in the classification of vascular malformations[3]. Lesions are identified first based on the prevailing vascular structure involved- arterial, venous, lymphatic, or capillary, also considering arteriovenous shunting and combined vascular defects[3]. The embryological 22 RADIOLOGY & IMAGING

23 background of the lesion is then considered for additional delineation[5]. Extratruncular lesions result from developmental arrest in the early reticular embryonic stage, prior to the development of vascular trunks. Extratruncular malformations may be infiltrating and diffuse or limited and localized. Truncular lesions result from a defect occurring during the stage of fetal development following the reticular stage, as the vascular trunks are developing. Truncular forms develop from stenosis or obstruction of vascular trunks, with resulting hypoplasia, or dilatation of vascular trunks, which in turn may be localized or diffuse[6]. Vascular Tumours: In their seminal paper, Mulliken and Glowacki[2], reported vascular tumors - then referred to as hemangiomas - to demonstrate specific mitotic activity and eventual involution, setting them apart from vascular malformations. Much has been discovered about vascular tumors, and while beyond the scope of this discussion, this information encompasses a variety of different entities. These include but are not limited to infantile hemangiomas and rapidly involuting and noninvoluting congenital hemangiomas, as well as more aggressive tumors, such as tufted angiomas, Kaposiform hemangioendotheliomas, and angiosarcomas. Infantile hemangiomas are the most common tumor of infancy and childhood affecting up to 12% of children with a female preponderance[7,8]. Histologically, these lesions stain positively for glucose transporter-1 protein (GLUT-1). Tumors typically appear between 2 wk and 2 mo of life and follow a proliferating phase, an involuting phase, and a state of complete involution[9,10]. Congenital hemangiomas are tumors that demonstrate intrauterine development with growth completed at birth[11]. These lesions more commonly affect the extremities, close to the joint, or on the head and neck, close to the ear[12]. In contrast to infantile hemangiomas, these lesions stain negative for GLUT-1[11,12]. Lesions are divided into two categories based on biologic activity: rapidly involuting congenital hemangiomas (RICHs) and noninvoluting congenital hemangiomas (NICHs). RICHs typically regress within 6-14 mo while NICHs do not regress and have a tendency for progression, usually leading to surgical excision[12]. Kaposiform hemangioendothelioma is a rare vascular neoplasm, which usually arises in the skin and infiltrates into the deeper tissues over time. Most cases are associated with consumptive coagulopathy or Kasabach-Merritt Syndrome, as well as lymphangiomatosis[13]. Vascular malformations: Vascular malformations are structural lesions resulting fromrom errors of vascular morphogenesis[2]. Differentiation of vascular malformations into high flow, low flow or mixed lesions is critical in developing treatment strategies. The distinction of truncal from extratruncal may provide insight in predicting response to treatment Imaging of Vascular anomalies: Several noninvasive imaging modalities are useful in characterizing vascular anomalies, contributing information about RADIOLOGY & IMAGING lesion size, flow characteristics and relationship to adjacent structures[14]. Conventional radiography plays a minor role, though may be valuable in defining bone and joint involvement and presence of phleboliths[14].contrast enhanced computed tomography (CT) and CT angiograph are useful in evaluating osseous involvement and phleboliths, but also provides information about enhancement, thrombosis, calcification, vascular anatomy and involvement of adjacent structures[14]. The use of ionizing radiation and relatively limited ability to provide information about flow dynamics decreases its usefulness. For these reasons ultrasonography (US) and magnetic resonance imaging (MRI) are the primary noninvasive imaging modalities used in the evaluation of vascular anomalies[15]. US is indispensable in the evaluation of superficial vascular lesions given its low cost, ease of use, high temporal and spatial resolution, and ability to 23

24 evaluate flow dynamics[14,16]. With US, hemangiomas are reliably differentiated from vascular malformations based on depiction of a well-circumscribed solid mass[16]. Hemangiomas and high-flow vascular malformations, including arteriovenous malformations (AVMs) and arteriovenous fistulae (AVFs), demonstrate arterial and venous waveforms on pulsed Doppler US, but are differentiated based on a lack of associated mass in AVMs and AVFs[15,16]. AVMs and AVFs will contain multiple enlarged subcutaneous arteries and veins on grey scale and color Doppler US with associated low-resistance arterial and venous waveforms on pulsed Doppler US[15,16]. Low-flow vascular malformations, including venous and lymphatic malformations, can be differentiated from high flow lesions based on Doppler analysis. Venous malformations contain enlarged subcutaneous vessels without an associated mass, are compressible and demonstrate venous flow on color and pulsed Doppler US[16]. Lymphatic malformations are characterized by macrocystic or microcystic spaces with or without debris separated by septae. On color and pulsed Doppler US these cysts will contain no flow, however the septa may contain small arteries and veins[16]. US is limited in its ability to evaluate deep lesions and lesions that involve bone[14]. MRI is the most valuable modality for imaging vascular anomalies due to its superior contrast resolution, ability to characterize flow dynamics, depiction of deep and adjacent structures and lack of ionizing radiation[14]. Most information needed to characterize a vascular anomaly can be obtained from T1-weighted, fat saturated T2-weighted and gradient echo MR sequences[15]. Basic MR imaging protocols should include each of these sequences in the axial plane along with fast spin echo T2weighted images in the coronal and sagittal planes[15,17]. Dynamic contrast-enhanced MRI can provide supporting information about flow dynamics[18] and may also be employed. On MRI, hemangiomas will appear as a mass[15,19] with flow voids and intermediate signal on T1-weighted images, flow voids and high signal on T2-weighted images, high signal within vessels on gradient echo sequences and arterial enhancement on contrast enhanced images[15, 19]. High-flow vascular malformations including AVMs and AVFs will also demonstrate flow voids and intermediate signal on T1-weighted images, flow voids and high signal on T2-weighted images, high signal within vessels on gradient echo sequences and arterial enhancement on contrast enhanced images, but no associated soft tissue mass[14-19]. Low flow lesions including venous malformations and lymphatic malformations can also be differentiated based on MRI. Venous malformations will appear as multiple serpentine tubular structures or amorphous dilated channels containing intermediate signal on T1 weighted images, high signal on T2 weighted images, intermediate signal on gradient echo sequences and delayed enhancement on dynamic contrast enhanced MRI[14-19]. Flow voids are not seen within venous malformations due to a lack of fast-flowing blood. Lymphatic malformations are characterized by micro- or macrocystic spaces that often contain fluid-fluid levels due to hemorrhage or proteinaceous material within the cysts[15].cysts will often be hyperintense on T2-weighted images, hypointense on T1 weighted images (though may be iso- to hyperintense depending on proteinaceous contents), and will not enhance[15,19]. When microcystic, the cystic spaces may not be visible with the fibrovascular stroma seen as regions of intermediate signal on T1-weighted images and high signal on T2-weighted images with associated enhancement on post-contrast images. Low Flow Vascular Anomalies: Capillary malformations present as flat pink or red macules that do not involute. These lesions result from abnormal morphogenesis of superficial dermal blood vessels, which lead to ectatic papillary dermal capillaries and postcapillary venules[20]. Histologically, these lesions stain positive for fibronectin, von Willebrand factor, and collagenous basement membrane proteins[21]. Particularly, in port wine stains, there is increased expression of vascular endothelial growth factor VEGF-A as well as its most active receptor VEGF-R2, which is suggestive of an underlying mechanism for pathogenesis[22]. These lesions occur in 0.3% of newborns without preponderance for gender[23]. Detection typically occurs at birth, although acquired capillary malformations are rarely identified. Capillary malformations can be seen with several different syndromes as described later. 24 RADIOLOGY & IMAGING

25 FIG 1: low flow vascular malformation in hemangioma Lymphatic malformations: Lymphatic malformations arise from abnormal development of the lymphatic system during the early phases of angiogenesis and may be diffuse, often described as lymphedema, or localized, commonly described as a lymphangioma[20]. These malformations are typically large, spongy masses that are non-tender. These lesions can affect any area of the body, but there is a propensity for the head and neck, where they are often referred to as cystic hygromas[20]. Sixty five to 75% of lesions present at birth whereas the remainder of cases appear within 2 years of age[24]. While most lesions are sporadic, some are occur as part of syndromes, such as CLOVES (Figure 3). Complications of these lesions may include bleeding or infection for superficial lesions and encroachment on other anatomic structures such as airways or abdominal viscera for deep lesions. Lymphatic malformations may be macrocystic (Figures 4, 5), consisting RADIOLOGY & IMAGING of lymphatic spaces arbitrarily fined as greater than two centimeters in diameter, microcystic, or a combination of macrocystic and microcystic. As these lesions are commonly encountered in infants and children ultrasound plays an important role in the diagnosis, staging, and treatment of lymphatic malformations. MR is useful in determining the type and anatomic relationships of lesions but often requires sedation or general anesthesia in children. High Flow vascular malforma- tion- High flow vascular malformation exhibits variable presentation dependent on location (Figures 11, 12). Superficial lesions may present as a warm painless mass with palpable bruit and associated dilated veins. Skin erosion and bleeding is possible (Figure 12). Deeper lesions may present with steal phenomena as the malformation deprives blood flow from downstream structures. Staging of these lesions can be accomplished by scoring according to the Schobinger clinical staging system[20,42]. Within this system, stage 1 describes a phase of quiescence where there is a cutaneous blush and skin warmth. In stage 2, there is expansion with a darkening blush, lesion pulsation, as well as a bruit or palpable thrill. Stage 3 is defined by destruction, namely pain, dystrophic skin changes, ulceration, distal ischemia, and steal. Finally, stage 4 is marked by decompensation or high output cardiac failure. High flow vascular malformations include macrofistulas, or truncular malformations, that consist of single or multiple arteries directly communicating with outflow veins without an interposed high resistance capillary system. In contrast, arteriovenous malformations, which are often extratruncular, consist of a low resistance nidus recruiting blood supply from numerous regional inflow arteries and draining by multiple outflow veins. 25

26 Fig 2 High flow vascular anomalies- hemangioma Syndromes associated with high flow and mixed venous Malformations: Hereditary hemorrhagic telangiectasia S Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder involving mutations in the transforming growth factor-beta signaling pathway result ing in irregular cytoskeletal architecture and abnormal vascular tubule formation characterized by telangiectasias and fistulous malformations. Incidence is estimated to be between 1 in 5000 to 8000 with males and females affected equally[52,53]. Onset of symptoms most commonly occurs within the second and third decades of life. Telangiectasias are seen on mucosal surfaces and associated with epistaxis and gastrointestinal bleeding. Arteriovenous fistulas, particularly in the lung, liver, brain and gastrointestinal tract are a major source of morbidity and mortality. While 30% of patients with HHT have pulmonary arteriovenous fistulas, 80% of pulmonary arteriovenous fistulas occur in patients with HHT. As these fistulas act as right to left shunts, patients can present with hypoxia, stroke or brain abscess and less frequently hemoptysis or hemothorax. Lesions may be single or multiple. Simple lesions consist of fistulas between a single segmental branch of the pulmonary artery and the pulmonary vein, or complex with multiple segmental pulmonary artery branches supplying the fistula. Fistulas with arterial supply greater than 3 mm in diameter are considered at greatest risk of complication. Surgical resection of pulmonary arteriovenous fistulas has currently been replaced by transcatheter occlusion. Superselective catheterization of the feeding pulmonary arterial branch close to the site of arteriovenous communication is required for placement of coils. Coil size selection, usually 20% larger than the target artery, is critical to avoid systemic coil embolization. Complete occlusion of each feeding artery is critical. Occasionally, occlusion of the aneurysmal draining vein can precede arterial occlusion in order to prevent systemic coil loss (Figure 17). Success of coil embolization approaches 80% but recanalization of the occluded artery or recruitment of additional feeding arterial supply results in recurrence of the fistula in up to 25% of patients, necessitating retreatment[54]. Careful follow-up of patients, therefore, is essential. Detachable coils or use of the Amplatzer occluder device may increase the safety of the procedure in select cases. 26 RADIOLOGY & IMAGING

27 Fig 3: MR T1 sequence show high flow anomalies. Figure 4: MR axial T1 W sequences, showing lymphatic malformations Parkes Weber syndrome Parkes Weber Syndrome is an OSCVA syndrome[55] (Overgrowth Syndrome with Complex Vascular Anomalies), characterized by extremity overgrowth and vascular anomaly. In contrast to the Klippel Trenaunay syndrome, venous abnormalities are associated with high flow arteriovenous malformations within the hypertrophied extremity. A third component of the syndrome is a cutaneous capillary malformation. Arteriovenous fistulas may form around the time of puberty, and exacerbation of the vascular abnormalities is associated with trauma (Figure 17). PTEN Hamartoma Syndrome: PTEN mutations promote stimulation of angiogenesis by the Akt/mTOR pathway[56]. PTEN Hamartoma Syndrome (PHTS) usually involves cutaneous lesions, capillary or capillary venous malformations, typically small deep tissue vascular malformations, and multiple high flow AVMs, associated with hamartomatous lesions[55]. Occasionally, lymphatic and venous malformations may be present. High flow AVMs may be present in the limbs, paraspinal region and dura. They are frequently intramuscular and associated with ectopic fat. The hamartomatous lesion, comprised of vascular clusters, fibrous tissue, large veins and fat, has been termed PTEN hamartoma of soft tissue. Cowden syndrome, Bannayan-Riley-Ruvalcaba syndrome (BRRS) and some instances of Proteus syndrome are classified together with PHTS. More extensive high flow AVMs are occasionally seen in the BRRS. Syndromes associated with low flow vascular malformations: Klippel trenaunay syndrome Klippel trenaunay syndrome (KTS) is another OSCVA syndrome with extremity overgrowth, associated with a superficial vascular stain, venous malformations, and usually partial aplasia of the deep venous system. The syndrome may also involve lymphatic anomalies. The vascular venous vascular malfor RADIOLOGY & IMAGING 27

28 mations in KTS are characterized as truncal malformations, and may be related to persistence of the embryonic dorsal vein system in the lateral aspect of the extremity (lateral marginal vein in the lower extremity). Large varicosities may result in venous thrombosis and pulmonary embolism. Coagulopathy and gram-negative sepsis are also complications. Limb gigantism is especially prominent when there is an associated lymphatic malformation. MRI is the mainstay of imaging in KTS, with sonography reserved for guiding interventions and for distinguishing venous from lymphatic components of malformations (Figures 18, 19). Catheter based venography is occasionally needed to determine the presence, absence or partial aplasia of the deep venous system, when this is not obvious on other imaging modalities. CLOVES Syndrome : The congenital lipomatous overgrowth, vascular malformations, epidermal nevi, and scoliosis and other skeletal deformities (CLOVES) syndrome consists of truncal lipomatosis, vascular malformations, and acral/musculoskeletal anomalies. The lipomatous lesions are often infiltrative and tend to recur following resection. Skeletal overgrowth and malformation are common in the extremities, as is scoliosis. Vascular lesions include capillary, lymphatic, venous and arteriovenous malformations. In contrast to the Proteus and BRRS syndrome there is no mental impairment. Treatment includes sclerotherapy of lymphatic and venous malformations and resection of lipomatous lesions[55]. Blue rubber bleb nevus syndrome : This syndrome consists of venous malformations of the skin and those within the gastrointestinal tract. The skin lesions are comprised of a compressible blue subcutantion. Clinical consequences generally result from gastrointestinal venous malformations, which may lead to occult or frank gastrointestinal bleeding. Maffucci syndrome: In this syndrome, enchondromas are found in coexistence with venous malformations. There is a high frequency of malignant transformation of the enchondromas into chondrosarcomas. Fig 5: Maffuci syndrome with multiple enchondromatosis with hemangioma 28 RADIOLOGY & IMAGING

29 Generalized Lymphatic Anomaly and Gorham-Stout disease: Generalized Lymphatic Anomaly (GLA) and GorhamStout Disease are two different disorders of the lymphatic system with overlapping features[57]. GLA is synonymous with generalized cystic lymphangiomatosis cystic angiomatosis and lymphangiomatosis, though the term GLA is preferred based on the ISSVA classification system. GLA is a multisystem disorder characterized by dilated lymphatic vessels[58,59]. Features of GLA may include splenic cysts, hepatic cysts, pleural effusions, and macrocytic lymphatic malformations, which may involve several organ systems, including bone[57-59]. On imaging, osseous lesions in GLA are seen as lucent lesions within the medullary cavity on radiography and display hyperintensity on T2-weighted MR imaging, but do not demonstrate cortical Conclusion: RADIOLOGY & IMAGING destruction[57,60]. Numerous bones are typically affected in GLA, and the axial and appendicular skeleton are both affected with similar frequency[57]. In cases of osseous involvement, patients may present with pain and pathologic fracture. Gorham-Stout disease, which has been called vanishing bone disease, is also a vascular anomaly of the lymphatics characterized by proliferation of lymphatic vessels within bone, resulting in progressive bony destruction[61]. Though the skeletal system is the primary site of disease in GSD, extra-osseous findings are also seen in GSD and include pleural effusions, splenic cysts, hepatic cysts, and infiltrating soft tissue abnormalities, which may extend from the bone into the adjacent soft tissues[57]. On imaging, osseous lesions are lytic, as in GLA, but are characterized by progressive osseous resorption and cortical destruction. On MRI, osseous lesions in GSD are most frequently accompanied by infiltrating soft tissue signal that is iso-to hypointense to muscle on T1-weighted images, hyperintense and heterogeneous on T2 weighted images, and enhances with contrast[57,62]. Infiltrative soft tissue is less common in GLA, which is seen in a minority of cases[57]. Unlike GLA, which affects the appendicular and axial skeleton with similar frequency, the axial skeleton is more commonly affected in GSD, with appendicular involvement seen in a minority of cases[57]. Macrocytic lymphatic malformations are infrequently seen in GSD[57]. As in GLA, patients with GSD may present with pain and pathologic fracture Accurate diagnosis of vascular malformations and their associated syndromes is often challenging but crucial in the formulation of appropriate treatment. The approach to the described entities requires an organized multidisciplinary team effort, with diagnostic imaging playing an increasingly important role in the proper diagnosis and a combined interventional radiologic and surgical treatment method showing promising results. References: 1.Yaşargil MG. Microneurosurgery: AVM of the Brain, History, Embryology, Pathological Considerations, Hemodynamics, Diagnostic Studies, Microsurgical Anatomy. Vol. IIIA: Thieme, Mulliken JB, Glowacki J. Hemangiomas and vascular malformations in infants and children: a classification based on endothelial characteristics. Plast Reconstr Surg 1982; 69: Belov S. Anatomopathological classification of congenital vascular defects. Semin Vasc Surg 1993; 6: Enjolras O, Wassef M, Chapot R. Color atlas of vascular tumors and vascular malformations. New York: Cambridge University Press, 2007: Lee BB, Laredo J, Lee TS, Huh S, Neville R. Terminology and classification of congenital vascular malformations. Phlebology 2007; 22: Lee BB, Lardeo J, Neville R. Arterio-venous malformation: how much do we know? Phlebology 2009; 24: Donnelly LF, Adams DM, Bisset GS. Vascular malformations and hemangiomas: a practical approach in a multidisciplinary clinic. AJR Am J Roentgenol 2000; 174: Paltiel HJ, Burrows PE, Kozakewich HP, Zurakowski D, Mulliken JB. Soft-tissue vascular anomalies: utility of US for diagnosis. Radiology 2000; 214: Rak KM, Yakes WF, Slater DD, Burke BJ. MR imaging of symptomatic peripheral vascular malformations. AJR Am J Roentgenol 1992; 159: Meyer JS, Hoffer FA, Barnes PD, Mulliken JB. Biological classification of soft-tissue vascular anomalies: MR correlation. AJR Am J Roentgenol 1991; 157:

30 Technical Role Of MR Elastography In 2016, New Prospective Approach To Other Advanced Sequences. Ujino K, Barnes ME, Cha SS, Langins AP, Bailey KR, Seward JB. Abstract: Magnetic Resonance Elastography (MRE) is a rapidly developing technology for quantitatively assessing the mechanical properties of tissue. The technology can be considered to be an imagingbased counterpart to palpation, commonly used by physicians to diagnose and characterize diseases. The success of palpation as a diagnostic method is based on the fact that the mechanical properties of tissues are often dramatically affected by the presence of disease processes such as cancer, inflammation, and fibrosis. MRE obtains information about the stiffness of tissue by assessing the propagation of mechanical waves through the tissue with a special magnetic resonance imaging (MRI) technique. The technique essentially involves three steps: 1. generating shear waves in the tissue, 2. acquiring MR images depicting the propagation of the induced shear waves and 3. processing the images of the shear waves to generate quantitative maps of tissue stiffness, called elastograms. MRE is already being used clinically for the assessment of patients with chronic liver diseases and is emerging as a safe, reliable and noninvasive alternative to liver biopsy for staging hepatic fibrosis. MRE is also being investigated for application to pathologies of other organs including the brain, breast, blood vessels, heart, kidneys, lungs and skeletal muscle. The purpose of this review article is to introduce this technology to clinical anatomists and to summarize some of the current clinical applications that are being pursued. Key words: elasticity imaging; palpation; mechanical properties; shear stiffness 30 RADIOLOGY & IMAGING

31 Fig 1: Imaging Modality contrast mechanisms Introduction The use of palpation to feel the difference in the mechanical properties of tissues and to differentiate abnormal and normal tissues remains a time-tested diagnostic tool for physicians. The mechanical properties of tissues vary widely among different physiological and pathological states (Duck, 1990; Sarvazyan et al., 1995) and hence have significant diagnostic potential. For instance, the relative hardness of malignant tumors is the basis for the use of palpation to detect breast cancer (Barton et al., 1999). Surgeons often detect liver tumors by simple touch at laparotomy that may not have been detected in preoperative imaging (Elias et al., 2005). However, except at surgery, palpation is applicable only to superficial organs and pathologies and is qualitative, subjective and limited to the touch sensitivity of the practitioner. Unfortunately, none of the conventional medical imaging techniques, such as computed tomography (CT), magnetic resonance imaging (MRI) and ultrasonography (US), are capable of depicting the properties that are assessed by palpation. These considerations have provided motivation for developing special imaging technologies for quantitatively assessing the mechanical properties of tissue. In engineering terms, the property assessed by palpation is called the elastic modulus. As shown in Figure 1, the elastic modulus of tissues varies by over five orders of magnitude and the tissue properties assessed by other modalities such as US, CT and MRI vary over a much smaller scale. Elasticity Imaging Investigators have evaluated a number of different approaches for imaging the mechanical properties of tissue. Most of the elasticity imaging methods apply some kind of stress or mechanical excitation to the tissue, measure the tissue response to this stimulus, and from this response calculate parameters that reflect the mechanical properties. Figure 2 shows a classification of these various approaches based on the three essential steps in elasticity imaging. RADIOLOGY & IMAGING 31

32 Fig 2: Various approaches to elasticity imaging A detailed review of all of the approaches is beyond the scope of this article; however some of the primary methods are highlighted below so that the reader can appreciate the breadth of the field. More technical discussions can be found in the literature, such as in (Greenleaf et al., 2003; Sarvazyan et al., 1995; Wilson et al., 2000). Excitation Application: The mechanical stress that is applied to tissue can be produced either through internal sources of motion like respiration or cardiac pulsations (Bae et al., 2007; Kanai, 2004; Mai and Insana, 2002) or through external mechanical sources of motion (Bercoff et al., 2004; Kruse et al., 2008; Xu et al., 2007). The stimulus can also be classified based on the temporal characteristics of the excitation as static (or quasistatic) or dynamic. Manual palpation can be thought of as a static elasticity assessment technique. Static compressions are widely employed for elasticity imaging and the techniques that use static forces include strain-encoding imaging (Osman, 2003), elastography (Ophir, 1991) and stimulated-echo elasticity imaging (Chenevert et al., 1998; Steele et al., 2000). Dynamic excitation techniques induce vibrations, usually in the range of 50 to 500 Hz, and image the propagation of the waves produced by the excitation throughout the tissue. These techniques include vibration sonoelastography (Lerner et al., 1990; Levinson et al., 1995) and magnetic resonance elastography (Muthupillai et al., 1995; Sack et al., 2004; Sinkus et al., 2000). Response to Applied Stress: The most critical component of elasticity imaging is to measure the response or strain of the tissue that results from the applied stress. Figure 2 lists the main methods used for the tissue response measurement: (1) optical, (2) mechanical, (3) ultrasonography and (4) magnetic resonance imaging. One of the early works in elasticity imaging investigated in 1952 used visible light to measure mechanical wave propagation to determine tissue elasticity and viscosity (Gierke et al., 1952). Since then, sophisticated optical imaging techniques like optical coherence tomography (OCT) elastography and tissue Doppler optical coherence elastography (tdoce) have been developed. (Rogowska et al., 2004;Ruikang et al., 2006;van Soest et al., 2007). Mechanical sensors, such as pressure sensors and accelerometers, have also been used to measure the tissue response to an applied stimulus since the underlying tissue properties are mechanical in nature (Egorov et al., 2006;Sarvazyan, 1998). Ultrasonography has been widely used for elasticity imaging. Both cross-correlation methods and Doppler imaging methods have been used to measure the tissue motion (Krouskop et al., 1987; Lerner et al., 1990; Yamakoshi et al., 1990). The term elastography as such was introduced to describe a technique (Ophir, 1991) in which the tissue strain resulting from external compression is mea 32 RADIOLOGY & IMAGING

33 sured with ultrasound, which provides a qualitative impression of the stiffness of tissue. Another method for elasticity imaging with ultrasound called transient elastography (TE, (de Ledinghen et al., 2007; Sandrin et al., 2003)) induces a single transient shear wave into tissue via a special transducer, images the propagation of this wave using ultrasound and uses this information to calculate the Young s modulus of the tissue. Even though ultrasound-based techniques are fast, inexpensive, and widely used, they also have limitations including the need for a suitable acoustic window for the ultrasound measurements and a limited depth for the measurements due to the limited penetration of ultrasound waves in tissue. One of the early implementations of MRI to measure tissue motion was for the assessment of cardiac function and pathologies using MR tagging techniques (Axel and Dougherty, 1989; Zerhouni et al., 1988). Other MR-based imaging techniques based on the synchronous use of quasistatic compressions and motion-encoding gradients (Chenevert et al., 1998; Plewes et al., 1995) have also been developed. Muthupillai et al. developed a technique called magnetic resonance elastography (MRE) which involves inducing harmonic vibrations of acoustic-range frequencies in tissue and imaging the propagation of these vibrations in the tissue to calculate quantitative values for tissue mechanical parameters (Muthupillai et al., 1995; Muthupillai et al., 1996). Mechanical Parameter Estimation: The third step in quantitative elasticity imaging is to process the acquired data to estimate the mechanical properties of the tissue. Typically, tissue is assumed to be linearly elastic, isotropic and Hookean for elasticity imaging techniques. The elastic properties that correspond to what is assessed by palpation are expressed as Young s modulus (E), or shear modulus (μ). For most soft tissues, the Young s modulus and the shear modulus are related by a simple scale factor of 3: E = 3μ, which means that the calculation of Young s modulus or shear modulus provides the same information. While obtaining quantitative values of the elastic properties of tissue may be preferable, obtaining a qualitative contrast between normal and abnormal tissues can be helpful in many applications. Most of the techniques that apply quasistatic excitations calculate tissue displacement or strain as qualitative indicators of the underlying mechanical properties (Mai and Insana, 2002; O Donnell et al., 1994; Osman, 2003). To calculate quantitative values of the shear modulus, for example, accurate determination of the accompanying tissue stresses is necessary, which is difficult due to complicated boundary conditions and unknown applied forces. On the other hand, with dynamic wave propagation techniques, quantitative shear modulus values can be calculated from the propagation of the shear waves using appropriate wave equations (Muthupillai et al., 1995; Sandrin et al., 2003). RADIOLOGY & IMAGING 33

34 Fig 3: Block diagram of external driver setup Magnetic Resonance Elastography Magnetic resonance elastography (MRE) is a dynamic elasticity imaging technique that uses mechanical waves to quantitatively assess the shear modulus (or stiffness) of tissues (Muthupillai et al., 1995). The technology is becoming available as an upgrade on conventional MRI scanners, and the most important initial clinical application has been for noninvasively assessing hepatic fibrosis, which increases the stiffness of liver tissue (Venkatesh et al., 2008b; Yin et al., 2007). The three basic steps of this MRE are 1. shear waves with frequencies ranging from Hz are induced in the tissue using an external driver, 2. the waves are imaged inside the body using a special MRI technique and 3. the resulting data are processed to generate quantitative images displaying the stiffness of tissue. The following sections highlight some of the key components of the MRE methodology and provide some sample applications under investigation. Generating Mechanical Waves in Tissue MRE typically uses vibrations of a single frequency (within the audio frequency range) generated by external driver devices. The electrical signal for these devices is created by a signal generator triggered by and synchronized to the MR pulse sequence and is amplified by an audio amplifier before being fed into the mechanical driver, as can be seen in Figure 3a. Over the years, several driving mechanisms have been developed, each with their own advantages and limitations (Tse et al., 2009). Three of the most commonly used driver systems are schematically shown in Figures 3b d. Figure 3b shows an electromechanical driver that works via the Lorentz force and utilizes the magnetic field of the main MRI magnet (Braun et al., 2003; Muthupillai et al., 1995). A piezoelectric stack driver system is shown in Figure 3c, where the motion created is based on the 34 RADIOLOGY & IMAGING

35 piezoelectric property of certain materials (Chen et al., 2006; Othman et al., 2005). Focused-ultrasound-based (FUSbased) radiation force has also been investigated as a means to create mechanical motion for various elasticity imaging strategies including MRE, where shear waves are created directly within tissue with externally placed ultrasound transducers (Bercoff et al., 2004; Nightingale et al., 2001; Wu et al., 2000). Another widely used method of creating the required vibrations for MRE utilizes the motion of the voice coils used in acoustic speaker systems. The required vibrations are again produced by the Lorentz force, but the static magnetic field is from a devoted permanent magnet present in the acoustic speaker (Asbach et al., 2008; Yin et al., 2007). These speakers, with their own permanent magnets, have to be placed away from the main MR magnet, thus this system necessitates an additional component to couple the vibrations produced by the speakers to the tissue. One approach is to enclose the area around the speaker cone or its equivalent, to use a long connecting tube to pneumatically conduct the harmonic pressure variations of the air into the scanner and to terminate the tube in a passive drum-like driver kept in contact with the tissue (pressure-activated driver, shown schematically in Figure 3d). This driver can be easily manipulated, and the portion of the driver system actually in the vicinity of the patient is made out of materials that do not produce MR image artifacts. This system is used by several groups for clinical hepatic MRE (Venkatesh et al., 2008b). Since the actual vibrations are produced RADIOLOGY & IMAGING by an active component different from the passive component in contact with the tissue, the passive component can be adapted to suit any organ of interest, such as the breast or brain. The amplitude of the vibrations induced within the tissue is very low and is maintained within vibration safety limits derived from a European Union directive limiting occupational exposure to wholebody and extremity vibrations (Ehman et al., 2008). Fig 4: Block diagram of MR Pulse sequences Imaging the Propagating Waves The fundamentals of MR imaging underpinning MRE can be found in references such as (Bernstein et al., 2004; Vlaardingerbroek and Den boer, 2003). Measuring the tissue motion produced by a driver with MRE is based on an MR imaging technique called phase-contrast MRI (Moran, 1982). Muthupillai et al. developed the technique of dynamic phase-contrast MRE where propagating shear waves in tissue are encoded into the phase of the MR images with the help of motion-encoding gradient (MEG) pairs (Muthupillai et al., 1995). After continuous harmonic motion is induced in the tissue, a MEG oscillating at the same frequency as the motion is applied and conventional MR imaging is performed. The phase contribution to the MR image ϕ due to the motion and the applied magnetic field gradient at a given position vector r and phase offset θ between the motion and the MEG can be written as where γ is the gyromagnetic ratio of the tissue protons, N is the number of gradient pairs used to sensitize the motion, T is the period of the motion-encoding gradient, G is its amplitude, ξ 0 is the peak amplitude of motion, and k is the wave number. This equation states that the phase of harmonically vibrating tissue is directly proportional to its displacement. Figure 4 shows a typical MRE pulse sequence using a gradient-recalled echo with the conventional radiofrequency (RF) pulse waveform, slice-selection gradient, phase-encoding gradient and frequency-encoding gradient. The motion-encoding 35

36 gradient (shown here only in the frequency-encoding direction) is placed after the RF excitation of the sample and before the measurement of the induced signal. Motion occurring in any direction can be encoded into the phase of the MR image by manipulating the axes on which the MEGs are placed. In this example, only the motion occurring in the frequency-encoding direction will be sensitized to and encoded into the image phase. The motion-encoding capability of this technique is very sensitive and can detect motion on the order of 100 s of nanometers (Muthupillai et al., 1996). An MR image thus obtained containing information about the propagating wave in its phase is called a wave image. Typically two such wave images are collected with opposite polarity of the MEG and a phase-difference image is calculated to remove non-motion-related phase information. The solid and the dotted lines in Figure 4 indicate the MEG waveforms with opposed polarities used sequentially to produce these phase-difference wave images. Figure 4 also schematically shows the induced continuous sinusoidal motion of the tissue and its temporal relationship with the MEG (θ). Changing this temporal relationship in subsequent acquisitions is utilized to acquire snapshots of the propagation of the waves, typically at 4 8 temporal samples (called phase offsets) spaced equally over a period of the wave motion, to show the propagation of the wave in MRE experiments and to permit processing of the data through time. From this temporal data, displacement information at the applied mechanical frequency can be extracted for subsequent processing and spurious phase information that is at other frequencies can be removed. In some applications where mechanical transient waves are being investigated as a tool to overcome some of the problems that arise due to the use of harmonic waves, such as wave reflections and interference, the series of images with increasing temporal delay values are acquired over a longer time interval to study the origination and evolution of the transient wave (McCracken et al., 2005). Since the motion-encoding gradients necessary for MRE are inserted into conventional MR pulse sequences, MRE can be implemented with many MR imaging sequences, each with its own advantages and limitations. Various groups have demonstrated using different pulse sequences for different applications and hence MRE pulse sequences based on spin echo (SE), gradient-recalled echo (GRE), balanced steady-state free precision (bssfp) and echo planar imaging (EPI) techniques exist (Bieri et al., 2006; Kruse et al., 2006; Maderwald et al., 2006; Rydberg et al., 2001). These pulse sequences can be designed to have the MEG frequency matched to the frequency of motion (optimally sensitive to motion of that particular frequency (Muthupillai Fig 5: MRE of inclusion phantom 36 RADIOLOGY & IMAGING

37 Fig 6: Liver stiffness due to Fibrosis, graded by MRE. et al., 1995)), a particular multiple of the motion frequency (which has lower motion sensitivity) to reduce the echo time for applications involving short-t2 tissues (Rump et al., 2007), or can be designed to be sensitive to motion with a broad range of frequencies (Asbach et al., 2008; Romano et al., 2003). Mechanical Parameter Estimation From the wave images indicating the propagation of shear waves in the tissue, mathematical inversion algorithms based on equations of motion, with simplifying assumptions like isotropy, homogeneity, and incompressibility, allow for the calculation of mechanical properties like the shear modulus to be used for clinical interpretations. The frequencydomain constitutive equation of motion for a general, homogeneous, anisotropic, viscoelastic material relates an applied stress to the resultant strain and can be expressed as a rank-4 tensor with 21 independent complex quantities (Auld, RADIOLOGY & IMAGING 1990). Making the assumption of isotropy reduces the number of independent quantities to two, typically the two Lamé constants λ and μ that predominantly control the longitudinal and shear strains, respectively. In soft tissues, the first Lamé parameter λ is usually much larger than the shear modulus μ, which makes the simultaneous calculation of both λ and μ impractical. However, the effect of λ can be simply neglected in some cases (if the excitation is primarily shear) or can be removed by filtering out longitudinal wave motion with bandpass filtering or curl filtering (Manduca et al., 2001). The shear modulus μ is a complex quantity and can be written as μr + iμi, where μr indicates the storage modulus and μi is the loss modulus reflecting the attenuation of a viscoelastic medium. From the complex shear modulus at a particular frequency, the shear wave speed can be calculated and an effective shear modulus (often called the shear stiffness) can be calculated using the simple relation: μ = ρvs2, where ρ is the density of the material (typically assumed to be around 1000 kg/m3 for tissue in MRE) and Vs is the wave speed of the shear wave. Since the wave speed can be written as a product of the operating frequency and the spatial wavelength, early MRE analysis methods focused on measuring the wavelength of the shear wave and were initially manually performed. Later, automatic algorithms that could calculate the wavelength (local frequency estimation, LFE; phase gradient, PG) were adopted and implemented (Manduca et al., 1996). As the field grew, algorithms that solved the wave equation directly to calculate both μr and μi were developed (direct inversion, DI; (Oliphant et al., 2001)). Even with these methods, the stiffness values are still often reported as the product of density and squared wave speed out of convention and convenience. A detailed review of these methods is provided in (Manduca et al., 2001). The images of the mechanical properties of tissue calculated in MRE are often referred to as elastograms and in this review all of 37

38 Fig 7: Hepatic MRE in patient with normal liver and with cirrhotic liver the elastograms presented indicate the tissue shear stiffness at a single frequency of operation. Depending on the technique used to derive the elastograms from the original MR images, elastograms can theoretically (e.g., absent any noise) have half the resolution of the native MR images (which can range from 50 µm to 10 mm depending on the application), however they more typically have one-third to onefifth of the MRI resolution. Shear wave interference can cause artifacts in the stiffness calculations using several of the above techniques, and a preprocessing technique called directional filtering has been developed to reduce these artifacts (Manduca et al., 2003a). Applications As is evident from the above discussion about MRE driver technology, imaging methods, and inversion techniques, there have been numerous MRE developments over the years, most of which have required preliminary testing before progressing to in vivo applications. Figure 5 shows an example of data obtained from a typical phantom experiment designed to test MRE principles in tissue-mimicking media. These phantoms are often constructed with regions of different stiffnesses. In this example, the background region is made up of a 2% agarose gelatin, the two soft inclusions that can be seen in the MR magnitude image in Figure 5a as hyperintense regions are made up of softer 1% agar and the hypointense stiff inclusions are made up of stiffer 3% agar. An electromechanical shear driver, shown schematically in Figure 5a, induces harmonic shear waves (of 100 Hz in this particular example) into the phantom by vibrating in the direction indicated with the double-sided arrow. The propagation of these waves in the phantom is imaged with an MRE pulse sequence sensitive to motion in the horizontal direction. One of the wave images is shown in Figure 5b, where the displacement in the phantom due to the shear wave 38 RADIOLOGY & IMAGING

39 85 kpa, respectively, for the background region, soft inclusions and the stiff inclusions. Due to the flexibility, noninvasiveness and potential clinical applications, the field of MRE has been rapidly evolving with new applications emerging for various organs including liver, spleen, kidney, pancreas, brain, cartilage, prostate, heel fat pads, breast, heart, lungs, spinal cord, bone, eye, and muscle (Asbach et al., 2008; Chen et al., 2009; Chopra et al., 2009; Dresner et al., 2001; Goss et al., 2006; Huwart et al., 2007; Kemper et al., 2004; Kolipaka et al., 2009; Kruse et al., 2009; Kruse et al., 2008; Litwiller et al., 2010a; Litwiller et al., 2010b; Lopez et al., 2008; Mariappan et al., 2010; Mariappan et al., 2009c; McGee et al., 2008; Ring- Fig 8: Breast MRE, highlighting large adenocarcinoma. Fig 9: Skeletal muscle MRE propagation is shown in units of microns. It can be seen that the wavelength decreases in the soft regions and increases in the stiff regions. From the wave data, a shear stiffness elastogram was calculated using the LFE inversion algorithm with directional filtering and is shown in Figure 5c in units of kpa. The stiffness contrast between the inclusions and the background gel is evident and both the soft and stiff inclusions can be visualized in this image based on the difference in their stiffnesses. Representative quantitative stiffness values for these regions can be calculated by averaging the values present in a region of interest drawn inside these regions. The values calculated for these regions were 32 kpa, 6 kpa and RADIOLOGY & IMAGING 39

40 Fig 10: Brain MRE leb et al., 2007; Shah et al., 2004; Sinkus et al., 2005b; Weaver et al., 2005; Xu et al., 2007; Yin et al., 2007). Table 1 provides example shear stiffness values obtained (and the frequency at which they were calculated) using MRE for a select set of organs. Challenges and Future Directions There are many challenges and opportunities for further technical development of MRE. The effective spatial resolution of the technique increases as the Fig 11: MRE, highlighting functional compartments of flexor muscles frequency of the applied waves is increased. Unfortunately, high-frequency shear waves are attenuated more rapidly than low-frequency waves, so there can be a tradeoff between spatial resolution and distance from the vibration source in some applications. Improved driver technology for MRE, such as the use of arrays of multiple vibration sources, is also under investigation (Mariappan et al., 2009d). Very stiff tissues such as bone, tendon, and cartilage require much higher vibration frequencies (in the kilohertz range) than soft tissues for evaluation with MRE. Current MRI scanners do not have gradient hardware that is capable of encoding wave motion at such high frequencies. These limitations may be addressed in the future with specialized hardware solutions (Lopez et al., 2008). While simple 2-dimensional sectional wave imaging may be adequate for some applications of MRE, many other applications require acquisition of wave data from an entire 3D volume. This type of acquisition may be prohibitively long using conventional sequences, but is becoming more practical with the introduction of special high-speed imaging techniques such as echo planar and 40 RADIOLOGY & IMAGING

41 other applications of MRE for determining tissue properties, structure, and function, such as the ones discussed here, are being investigated which could offer valuable information to clinicians and researchers in the future and interest in the field continues to grow rapidly. References 1. Asbach P, Klatt D, Hamhaber U, Braun J, Somasundaram R, Hamm B, Sack I. Assessment of liver viscoelasticity using multifrequency MR elastography. Magn Reson Med. 2008; 60: [PubMed: ] 2. Axel L, Dougherty L. MR imaging of motion with spatial modulation of magnetization. Radiology. 1989; 171: [PubMed: ] 3. Bae U, Dighe M, Dubinsky T, Minoshima S, Shamdasani V, Kim Y. Ultrasound thyroid elastography using carotid artery pulsation: preliminary study. Journal of Ultrasound in Medicine. 2007; 26: [PubMed: ] Fig 12: Typical shear stiffness values of various tissues 4. Basford JR, Jenkyn TR, An KN, Ehman RL, Heers G, Kaufman KR. Evaluation of healthy and diseased muscle with magnetic resonance elastography. Archive of Physical Medicine and Rehabilitation. 2002; 83: parallel imaging in MRE (Glaser et al., 2006; Kruse et al., 2006). The mathematical techniques used to process the wave data to generate elastograms have also improved significantly in recent years, but there are still many opportunities to advance these methods and to generate additional tissue characterization parameters, such as estimates of mechanical anisotropy, nonlinearity, and viscoelastic behavior (Asbach et al., 2008; Manduca et al., 2003b; Romano et al., 2005; Sack et al., 2002; Sack et al., 2004; Sinkus et al., 2005a; Sinkus et al., 2005b). RADIOLOGY & IMAGING Conclusions Elasticity imaging has received considerable attention due to its intuitive source of mechanical contrast paralleling the information provided by palpation and the significant diagnostic potential that this information can provide. Magnetic resonance elastography is an MRI-based technique which is capable of noninvasively assessing tissue stiffness and it has already been shown to be beneficial as a clinical tool for the diagnosis of hepatic fibrosis. A number of 5. Bercoff J, Tanter M, Fink M. Supersonic shear imaging: a new technique for soft tissue elasticity mapping. Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on. 2004; 51: Braun J, Braun K, Sack I. Electromagnetic actuator for generating variably oriented shear waves in MR elastography. Magnetic Resonance in Medicine. 2003; 50: [PubMed: ] 7. Chen J, Ni C, Zhuang T. Imaging mechanical shear waves induced by piezoelectric ceramics in magnetic resonance elastography. Chinese Science Bulletin. 2006; 51:

42 Technical Recent Advances And Technique- Role Of MR Urography In Modern Day Practise JR Basford MD, TR Jenkyn MD, KN Ane MD, RL Ehman MD, G Heers MD, KR Kaufman MD Abstract: Magnetic resonance (MR) urography comprises an evolving group of techniques with the potential for allowing optimal noninvasive evaluation of many abnormalities of the urinary tract. MR urography is clinically useful in the evaluation of suspected urinary tract obstruction, hematuria, and congenital anomalies, as well as surgically altered anatomy, and can be particularly beneficial in pediatric or pregnant patients or when ionizing radiation is to be avoided. The most common MR urographic techniques for displaying the urinary tract can be divided into two categories: static-fluid MR urography and excretory MR urography. Static-fluid MR urography makes use of heavily T2weighted sequences to image the urinary tract as a static collection of fluid, can be repeated sequentially (cine MR urography) to better demonstrate the ureters in their entirety and to confirm the presence of fixed stenoses, and is most successful in patients with dilated or obstructed collecting systems. Excretory MR urography is performed during the excretory phase of enhancement after the intravenous administration of gadolinium-based contrast material; thus, the patient must have sufficient renal function to allow the excretion and even distribution of the contrast material. Diuretic administration is an important adjunct to excretory MR urography, which can better demonstrate nondilated systems. Static-fluid and excretory MR urography can be combined with conventional MR imaging for comprehensive evaluation of the urinary tract. The successful interpretation of MR urographic examinations requires familiarity with the many pitfalls and artifacts that can be encountered with these techniques. Key words: Static fluid MR urography, Cine MR urography, Excretory MR urogrphy. 42 RADIOLOGY & IMAGING

43 Introduction A variety of techniques have been developed for imaging the urinary tract. Of these techniques, only two computed tomographic (CT) urography and magnetic resonance (MR) urography have the potential to provide a comprehensive assessment of the urinary collecting system, renal parenchyma, and surrounding structures. Although CT urography is nearing its potential in terms of spatial resolution, tissue differentiation, and elucidation of the renal anatomy, MR urography is a more nascent technology. MR urography is an evolving group of techniques with the potential to noninvasively provide the most comprehensive and specific imaging test available for many urinary tract abnormalities without the use of ionizing radiation (1,2). At the same time, formidable limitations and challenges remain for MR urography, including its relative insensitivity for renal calculi, relatively long imaging times, sensitivity to motion, and lower spatial resolution compared with CT and radiography. In this article, we review the most common MR imaging techniques used to image the urinary tract and discuss special considerations (pediatric patients, pregnant patients, renal insufficiency, imaging at 3 T) related to MR urography. In addition, we discuss and illustrate potential clinical applications of MR urography with respect to urolithiasis, urinary tract obstruction unrelated to urolithiasis, hematuria, congenital anomalies, and preand postoperative assessment. We also describe various pitfalls and artifacts associated with this modality. RADIOLOGY & IMAGING MR Urographic Techniques The most common MR urographic techniques used to display the urinary tract can be divided into two categories: (a) static-fluid MR urography (also known as static MR urography, T2weighted MR urography, or MR hydrography), and (b) excretory MR urography (also known as T1-weighted MR urography) (1,3,4). Static-Fluid MR Urography T2-weighted techniques were the first clinically relevant means of visualizing the urinary tract with MR imaging (5 10). Static-fluid MR urography treats the urinary tract as a static column of fluid, using one of a variety of T2-weighted sequences that exploit the long T2 relaxation time of urine (11). Therefore, static-fluid MR urographic techniques closely resemble those used for T2-weighted MR cholangiopancreatography. Breath-hold T2-weighted MR urograms can be obtained with either thickslab single-shot fast spin-echo techniques or similar thin-section techniques (eg, half-fourier rapid acquisition with relaxation enhancement, single-shot fast spinecho, single-shot turbo spin-echo). The signal intensity of background tissues can be adjusted by modifying the echo time or using fat suppression. Three-dimensional (3D) respiratory-triggered sequences can be used to obtain thin-section data sets that can then be postprocessed to create volume-rendered (VR) or maximum-intensity-projection (MIP) images of the entire urinary tract (11,12). Heavily T2-weighted static-fluid MR urograms resemble conventional excretory urograms and are useful for quickly identifying the level of urinary tract obstruction. However, identifying the cause of obstruction often requires additional sequences (8). Static-fluid MR urography does not require the excretion of contrast material and is therefore useful for demonstrating the collecting system of an obstructed, poorly excreting kidney (10). Static-fluid MR urograms can be obtained with single-shot 43

44 fast spin-echo techniques in 1 2 seconds, which allows multiple images to be obtained sequentially in a relatively short period of time and played as a cine loop (13). Such image series ensure that both ureters are distensible along their entire lengths and that no fixed narrowings or standing columns exist. Cine MR urography is particularly helpful in confirming the existence of urinary tract stenosis (13). When acquiring a series of static-fluid MR urograms to be viewed in cine mode, one should allow 5 10 seconds between acquisitions to prevent radiofrequency saturation of the tissues, which causes progressive signal intensity loss on the images. Because cine MR urography is quick and easy to perform, we have made it a routine part of our MR urography protocol. The T2 shortening effect of gadolinium prevents successful application of static-fluid MR urography during the excretory phase after the intravenous administration of gadolinium-based contrast material. Because static-fluid MR urography depends on the presence of urine within the collecting systems rather than the excretory function of the kidneys, it is ideally suited for patients with dilated, obstructed collecting systems, nondilated systems, the use of hydration, diuretics, or compression may enhance the quality of MR urography (9). Normal and abnormal fluid-filled structures can interfere with static-fluid MR urography, since the T2-weighted techniques used to display the urinary tract are not specific for urine. For this reason, intravenous hydration may be preferable to oral hydration prior to static-fluid MR urography in patients with nondistended ureters. Alternatively, acquisition planes or postprocessing reconstruction volumes can be adjusted to exclude bowel or other fluid-containing structures. At our institution, we do not use compression during MR urography Excretory MR Urography Excretory MR urography is roughly analogous to CT urography and conventional intravenous urography. A gadolinium-based contrast agent is administered intravenously, and the collecting systems are imaged during the excretory phase. Gadolinium shortens the T1 relaxation time of the urine, allowing the urine to initially appear bright on T1-weighted images. At standard doses of 0.1 mmol/kg, gadolinium-based contrast material quickly becomes concentrated in the urine, and sufficiently concentrated contrast material reduces the signal intensity of the urine due to T2* effects (Fig 5). This effect may be overcome with the use of lowdose gadolinium-based contrast material administration (as low as 0.01 mmol/kg), although such a technique does nothing to distend the collecting systems (14). Lowdose gadolinium-based contrast material administration has also been combined with oral hydration in an attempt to improve dilution and dispersion of excreted gadolinium-based contrast material throughout the collecting systems while improving ureteral distention (15). Unfortunately, MR urography performed with any amount of gadolinium-based contrast material without a pharmacologic means of enhancing urine flow tends to be suboptimal (16). Diuretic administration can improve the quality of excretory MR urography by enhancing urine flow, resulting in dilution and uniform distribution of gadolinium-based contrast material throughout the urinary tract (17 19). One additional benefit of diuretic administration is expansion of the temporal window during which one may obtain images after gadolinium 44 RADIOLOGY & IMAGING

45 administration, since T2* effects become less limiting. Fig 1: Excretion urography following subtraction. A relatively low dose of furosemide on the order of 0.1 mg/kg (ie, 5 10 mg for adults) is typically used for MR urography provided no contraindications exist (1,3,20 22). For average-sized adults, we have found that a 5-mg dose of furosemide typically yields excellent image quality while permitting the patient to finish the examination without having to void. Symptoms of acute ureteral obstruction may be exacerbated by the administration of a diuretic, although such occurrences seem to be rare. In a report by Sudah et al (23), only one of 26 patients who presented with acute flank pain due to calculi developed exacerbation of symptoms after the administration of 0.1 mg/kg of furosemide for excretory MR urography. Contraindications for furosemide administration include anuria and hypersensitivity to furosemide, and electrolyte imbalance or hypotension should be corrected before administering furosemide. Patients who are allergic to sulfonamides may also be allergic to furosemide. The optimal dose of gadolinium-based contrast material for diuretic-augmented MR urography has yet to be established. Nolte-Ernsting et al (1) advocated a gadolinium-based contrast material dose of 0.05 mmol/kg for diuretic-augmented excretory MR urography. Although doses of contrast material of less than 0.05 mmol/kg may yield satisfactory urographic images, concern exists that soft-tissue imaging will be compromised if the gadolinium dose is not sufficient. The primary RADIOLOGY & IMAGING imaging sequence for excretory MR urography is the 3D gradient-echo sequence (3,23). Fat suppression enhances the conspicuity of the ureters and is recommended. Depending on the degree of background suppression desired, either a 3D soft-tissue imaging type sequence such as VIBE (volumetric interpolated breathhold examination), FAME (fast acquisition with multiphase Efgre 3D), THRIVE (T1-weighted high-resolution isotropic volume examination), or liver acquisition with volume acceleration (LAVA) or a sequence normally used for MR angiography will suffice. Most modern imagers are capable of imaging the kidneys, ureters, and bladder in their entirety with a coronal 3D gradient-echo sequence during a single breath hold. Motion suppression is critical for MR urographic sequences, and breath-hold acquisitions have been shown to better demonstrate the pelvicaliceal systems compared with respiratory triggering (22). A coronal through-plane resolution of 2 4 mm is generally possible on newer imagers depending on the breath-holding ability of the patient. For patients with a limited capacity to hold their breath, adequate spatial resolution can be achieved by imaging the urinary tract in segments. Imaging the urinary tract in segments with a smaller field of view and thinner sections also allows the acquisition of high-detail images of the collecting systems, although the degree of detail obtainable is limited by the signal-to-noise ratio (SNR). The use of echoplanar sequences for excretory MR urography has been described, although aside from reduced acquisition time, such techniques appear to offer few advantages over more conventional 3D gradient-echo techniques (22). Excretory MR urography requires the excretion of gadolinium into the renal collecting systems to be effective. Therefore, excretory MR urog- 45

46 raphy has no role in the evaluation of patients with severely compromised renal function and may require significantly delayed imaging in patients with urinary tract obstruction. In the case of a markedly dilated ureter, static-fluid MR urography is usually sufficient, although the use of gadolinium-based contrast material will occasionally help distinguish between high-grade partial and complete ureteral obstruction. strengths below 1.5 T. All studies described in this article were performed on a 1.5-T imager with an eight-channel phased-array torso coil unless otherwise specified. Although most of the newly developed torso coils allow coverage of the entire abdomen and pelvis in the axial plane with a single acquisition, we image the abdomen and pelvis separately using the maximum number of available coil elements for each acquisition to maximize SNR and to allow high-resolution breathhold imaging. Most of the new, commercially available torso coils are compatible with sensitivity-encoding parallel imaging techniques. Use of parallel imaging reduces imaging time and the potential for respiratory motion artifacts. The improvement in image quality related to fewer respiratory artifacts usually more than compensates for the loss in SNR related to the use of parallel imaging. We limit our parallel imaging to acceleration factors of 2, since higher acceleration factors result in poor image quality on our current imagers. Mechanical compression has been used by some technologists to aid in urinary tract distention, although we have not found compression to be necessary (25). Patient Preparation Having patients void prior to entering the imager improves their comfort and prevents interruption of the study at an inopportune time. If no contraindications (eg, fluid restriction, congestive heart failure) exist, our patients are given 250 ml of normal saline solution intravenously at the start of imaging. Bowel contents are often bright with the T1- and T2-weighted sequences used for MR urography. We have found the use of oral negative contrast agents helpful in reducing the signal intensity of bowel contents, although the use of such agents is not required for MR urography. In most cases, imaging can be performed successfully with the patient supine. Imaging Sequences Hardware and Accessories It would be impractical to address every possible commercially available hardware configuration in an article such as this one. Therefore, we will speak primarily from our own experience regarding hardware. Satisfactory MR urograms can be obtained at either 1.5 T or 3 T; we do not have experience performing MR urography at field T2-weighted imaging can be performed with a variety of different sequences depending on the available equipment. For fat-suppressed T2weighted imaging of the renal parenchyma and pelvic organs, we prefer a respiratory-triggered fast spin-echo sequence. For standard non-fatsuppressed T1-weighted imaging, in-phase and opposed-phase gradient-echo sequences can be useful for detecting intracellular lipid in incidental adrenal masses and clear cell carcinoma of the kidney as well as for characterizing some angiomyolipomas. 46 RADIOLOGY & IMAGING

47 For cine imaging of the ureters, a thick-slab, heavily T2-weighted single-shot fast spin-echo sequence similar to sequences used for MR cholangiopancreatography is performed. This sequence is typically performed times with 5 10 seconds between acquisitions to prevent tissue saturation. The total number of thickslab acquisitions can be varied to fit the circumstances. For contrast material enhanced T1-weighted imaging of the kidneys, a 3D interpolated fat-suppressed gradient-echo sequence combined with parallel imaging suffices. By obtaining pre- and postcontrast images using identical imaging parameters and respiratory cessation, a subtracted data set can be obtained that is useful for assessing the enhancement of solid masses. Acquiring a postcontrast data set during the arterial phase allows assessment of the renal arteries. After two postcontrast acquisitions, we immediately image through the urinary bladder to ensure that we obtain images with bladder wall enhancement prior to the arrival of gadolinium-based contrast material via the ureters. This procedure prevents mixing artifacts, which may obscure bladder tumors. Excretory phase images can be obtained approximately 5 minutes after contrast material injection in nonobstructed patients with normal or mildly impaired renal function. Special Considerations Pediatric Patients The pediatric patient presents unique technical challenges for MR urography (26 30), including smaller physical size, inconsistent breath holding, and increased cardiac and respiratory rates (29). The majority of our pediatric patients are less than 6 years old and require sedation (27 29). Sedated patients can be successfully imaged during quiet respiration, although the use of respiratory-gated acquisitions has been described (31). Our pediatric MR urography protocol has evolved considerably over time. For excretory MR urography, we currently hydrate patients with 10 ml/kg of normal saline solution and administer furosemide at a dose of 0.1 mg/ kg up to a maximum of 5 mg prior to the administration of gadoliniumbased contrast material (standard dose of 0.1 mmol/kg). In pediatric patients with highgrade obstructions, static-fluid MR urography can be used to assess nonfunctioning systems. Staticfluid MR urography has a distinct advantage over excretory urography, which routinely presents problems in document- RADIOLOGY & IMAGING 47

48 ing the course and insertion of ureters when there is obstruction or poor function (26,28 30). In pediatric patients, performing dynamic contrast-enhanced imaging in the coronal plane allows improved assessment of vascular structures, such as crossing vessels in the setting of UPJ obstruction (28). This approach also allows contemporaneous imaging of the kidneys, ureters, and bladder, given the small size of many pediatric patients. Time signal-intensity curves have been successfully used to assess renal obstruction in an effort to duplicate the curves generated with diuretic-enhanced renal scintigraphy, although the generation of curves based on segmentation of the renal cortex and medulla may be time consuming in the absence of software automation (32 34). Preliminary studies have also shown the potential of MR urography to suggest the diagnosis of vesicoureteral reflux on the basis of time signal-intensity curves generated from diuretic-augmented excretory MR urographic images obtained over a period of 40 minutes (35). Pregnant Patients Contrast-enhanced MR urography is generally unnecessary in pregnant women. Instead, T2weighted (static-fluid) urography is performed. Multiple acquisitions (cine MR urography) may be necessary to visualize the entire ureters and exclude fixed narrowings or filling defects. In the latter stages of pregnancy, imaging with the patient in the left lateral decubitus position helps reduce pressure exerted on the inferior vena cava by the gravid uterus. Roy et al (36) reported excellent results with T2-weighted MR urography in identifying urinary tract dilatation and level of obstruction in 17 pregnant patients. The challenge of interpreting MR urographic images obtained during pregnancy remains the differentiation of physiologic hydronephrosis from pathologic obstruction (36 38). The MR urographic findings of physiologic hydronephrosis that have been described include compression of the midureter with tapering at the pelvic brim and no discernable filling defect. Tapering at another level suggests an alternative diagnosis, such as ureteral stone. The ureter below the level of compression should be relatively collapsed, although this segment can be seen to intermittently fill and empty at cine urography. A standing column of urine between the site of physiologic compression and the ureterovesical junction suggests the presence of a distal ureteral stone. In cases of acute calculus obstruction, renal and perirenal edema are often present. 48 RADIOLOGY & IMAGING

49 Renal Insufficiency The success of static-fluid MR urography depends on the presence of fluid within the urinary collecting system irrespective of renal function. Any patient who can undergo MR imaging can potentially undergo static-fluid MR urography, although the latter may be of limited value for nondilated collecting systems. The success of excretory MR urography depends on the excretion of gadolinium into the renal collecting systems. Consequently, patients with severely compromised renal function are poor candidates for excretory MR urography. In the past, excretory MR urography has been advocated for use in patients with less severe renal insufficiency as a means of avoiding the use of iodinated contrast material, given the reported low nephrotoxicity of gadolinium chelates at standard clinical doses (39 42). Relatively recent reports linking gadolinium administration to a disorder known as nephrogenic systemic fibrosis have resulted in new recommendations to avoid (whenever possible) the use of gadolinium-based contrast material in patients with moderate to severe renal insufficiency (43 48). It is important to note that the factors contributing to the development of nephrogenic systemic fibrosis remain an area of intense investigation, and physicians are encouraged to stay abreast of new developments and recommendations regarding the use of gadolinium-based contrast material in patients with renal insufficiency. Pitfalls and Artifacts RADIOLOGY & IMAGING As with any MR imaging technique, one must be aware of potential pitfalls when interpreting findings at MR urography (67). When reviewing MR urographic images created with MIP or VR algorithms, one should always consult the original data (source images) to ensure that small filling defects are not obscured by surrounding highsignal-intensity urine. Thick-slab acquisitions may also mask filling defects and should be used primarily to document the presence and level of obstruction. Whereas small intrarenal calculi are usually inconspicuous at MR imaging, large calculi can mimic a dilated, poorly functioning collecting system on T1-weighted images. However, this pitfall is easily avoided because urine is typically bright and calculi are typically dark on unenhanced T2-weighted images. Of course, correlation of the MR urographic findings with other available imaging findings such as radiographic or CT findings is always a good idea. Another mimic of a dilated intrarenal collecting system is the renal sinus cyst.when viewed on T1- or T2-weighted images obtained prior to the intravenous administration of contrast material, renal sinus cysts have the same signal intensity as urine. Therefore, renal sinus cysts are best differentiated from hydronephrosis on postcontrast excretory phase images. Susceptibility artifact from metallic objects such as surgical clips can interfere with the visualization of ureteral segments or create the appearance of a ureteral stenosis. As with renal calculi, correlation with radiographic or CT findings can be helpful, although most regions of susceptibility artifact can be correctly identified on gradient echo source images. Air from recent intervention or an indwelling nephrostomy tube may result in filling defects that simulate calculi. Hemorrhage into the renal collecting systems may appear bright on gradient-echo 49

50 T1-weighted images and may be obscured by gadoliniumbased contrast material. Therefore, we always perform precontrast gradient-echo T1-weighted imaging in at least one plane. Hemorrhage can also potentially interfere with static-fluid MR urography by reducing the signal intensity of urine. Decreasing the echo time at T2-weighted imaging may help overcome this limitation to some extent. Ureteral peristalsis may occasionally result in ghost artifacts on 3D gradient-echo images, although these artifacts rarely interfere substantially with interpretation (22). Conclusions When properly performed, MR urography can be a valuable means of noninvasively assessing the urinary tract. Static-fluid and excretory MR urography can be combined with conventional MR imaging to provide a comprehensive evaluation of the kidneys, ureters, bladder, vasculature, and soft tissues in patients with symptoms referable to the urinary tract. T2-weighted techniques are excellent for demonstrating dilated or obstructed collecting systems, whereas excretory MR urography provides excellent visualization of nonobstructed systems. MR urography can be useful for assessing patients with a variety of urinary tract disorders and allows the evaluation of pediatric and pregnant patients without the use of ionizing radiation. The successful interpretation of MR urographic examinations requires familiarity with the numerous potential pitfalls and artifacts that may be encountered. References 1. Nolte-Ernsting CCA, Staatz G, Tacke J, et al. MR urography today. Abdom Imaging 2003;28: Verswijvel GA, Oyen RH, Van Poppel HP, et al. Magnetic resonance imaging in the assessment of urologic disease: an all-in-one approach. Eur Radiol 2000;10: Nolte-Ernsting CCA, Adam GB, Gu nther RW. MR urography: examination techniques and clinical applications. Eur Radiol 2001;11: Garcia-Valtuille R, Garcia-Valtuille AI, Abascal F, et al. Magnetic resonance urography: a pictorial overview. Br J Radiol 2006;79: Sigmund G, Stoever B, Zimmerhackl LB, et al. RARE-MR-urography in the diagnosis of upper urinary tract abnormalities in children. Pediatr Radiol 1991;21: Roy C, Saussine C, Jahn C, et al. Evaluation of RARE-MR urography in the assessment of ureterohydronephrosis. J Comput Assist Tomogr 1994;18: Aerts P, Van Hoe L, Bosmans H, et al. Breath hold MR urography using the 50 RADIOLOGY & IMAGING

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53 Functional MR techniques applications in biological effects of endometrial carcinoma Md Ameen MD, Kumaran MD DEPARTMENT OF RADIODIAGNOSIS, VELLAMMAL MEDICAL COLLEGE, MADURAI, TAMILNADU, INDIA OBJECTIVE: Functional MR techniques report on a variety of biologic features of tumors: dynamic contrast-enhanced, diffusion-weighted, and intrinsic susceptibility-weighted MRI and MR spectroscopy reflect, at a simplistic level, vascularity, cellularity, hypoxic status, and metabolism, respectively. This article reviews the evidence for each of the functional MR readouts to determine these clinical end points and thus influence the management of endometrial cancer. Methods. Between Febrauary 2016 to October 2016 on 78 patients who were diagnosed with and treated for endometrial carcinoma included in this study. Main outcome measure was the correlation between the depth of myometrial invasion and cervical invasion by preoperative MRI, transvaginal sonography, hysteroscopy with directed biopsy study and the subsequent histopathological findings following examination of the hysterectomy specimen. Results: The mean age was 54.6 years old and the most common histological subtype was the endometrioid type of endometrial adenocarcinoma (87.8%). In the evaluation of deep myometrial invasion (>50%), sensitivity, specificity, positive and negative predictive value and positive and negative likelihood ratios of MRI were 70.00%, 94.87%, 77.78%, 92.50%, 13.65, 0.316, respectively. For cervical invasion, these values were 72.73%, 98.85%, 88.89%, 96.63%, 63.27, 0.30, respectively. Conclusion: MRI is the superior diagnostic method to detect the myometrial invasion and cervical invasion. Conclusions. Preoperative MRI in patients with an endometrial carcinoma can be used to estimate myometrial and cervical invasion. Therefore, in combination with the histological grading of the tumor, a preoperative MRI can be used to select patients at high risk of nodal involvement. Key Words: Magnetic resonance imaging, myometrium, endometrial carcinoma, dynamic contrast MR, diffusion weighted MR. INTRODUCTION: CT & MRI Endometrial cancer is the fourth most common malignancy in females and the most common malignancy of the female reproductive tract (1). There were an estimated 43,470 new cases and approximately 7950 deaths from RADIOLOGY & IMAGING endometrial cancer in the United States in 2010 (2). The prevalence of endometrial cancer is increasing due to an aging population combined with rising levels of obesity (3). Approximately 75% of cases occur in postmenopausal women, with the median age at diagnosis being 70 years. Adenocarcinomas account for 90% of endometrial neoplasms, whereas uterine sarcomas are relatively rare and account for only 2% 6%; the remaining histologic types include adenocarcinoma with squamous cell differ- 53

54 entiation and adenosquamous carcinoma (4,5). Endometrial cancer is staged with the International Federation of Gynecology and Obstetrics (FIGO) system, which recently underwent a major revision (6). Prognosis depends on a number of factors, including stage, depth of myometrial invasion, lymphovascular invasion, histologic grade, and nodal status. Depth of myometrial invasion is the most important morphologic prognostic factor, correlating with tumor grade, presence of lymph node metastases, and overall patient survival. The prevalence of lymph node metastases increases from 3% with superficial myometrial invasion to 46% with deep myometrial invasion (7,8). Consequently, preoperative information about depth of myometrial invasion and histologic grade is essential in tailoring the surgical approach for these patients Morphologic imaging with CT or MRI has formed the mainstay of imaging assessment. CT has the advantage of speed and coverage, delivering whole-body scans in under 1 minute and is less prone to breathing artifacts and image distortion. MRI, however, has the advantage of exquisite soft-tissue contrast, enabling distinction of tumor from normal tissue but is underutilized in many institutions because of cost, availability, physician preference, and exclusion of MRI from most FIGO (International Federation of Gynecology and Obstetrics) staging systems. MRI also offers the potential of functional imaging, which enables more detailed characterization of tumors vascularity, cellularity, metabolism, and oxygenation. The derived quantitative parameters from these techniques potentially can be used as biomarkers of prognosis and response. This article reviews the current evidence for the use of functional MRI techniques in the context of current imaging practice and outlines the potential in the three most common gynecologic malignancies (ovary, endometrium, and cervix). Diffusion-weighted and dynamic multiphase contrast medium enhanced MR imaging sequences have been shown to improve the accuracy of MR imaging in assessing the depth of myometrial invasion and can be used to assess tumor response to therapy and to differentiate tumor recurrence from posttreatment changes (12 14). In this article, we discuss the MR imaging assessment of endometrial cancer in terms of imaging protocol, recent modifications to the FIGO staging system, imaging appearances, and the complementary roles of diffusion-weighted and dynamic contrast-enhanced MR imaging. DWI routinely supplemented with DCEMRI in specific clinical scenarios. Intrinsic susceptibility-weighted BOLD MRI and MRS are rarely used in clinical practice and are primarily investigational tools. DCE-MRI quantifies the pharmacokinetic profile of an injected contrast agent with consecutive rapid image acquisition before, during, and after administration. The passage of the paramagnetic agent increases signal intensity; the degree of enhancement is determined by blood flow, vascular density, capillary permeability, and capillary surface area in the early vascular phase and by extravascular space volume in the interstitial phase. The changes in T1 signal intensity are determined using a T1-weighted 3D-gradient-echo fat-suppressed sequence in which a slab of 60 slices with an in-plane spatial resolution of approximately 1.5 mm may be acquired with a temporal resolution of seconds. Data are analyzed either using a model-free approach and generating a semiquantitative parameter, such as initial area under the gadolinium curve, or by applying a pharmacokinetic model [1] to generate quantitative parameters, such as transfer constant and extracellular extravascular leakage space. DWI, exploits the thermally driven motion of water molecules, which in biologic tissue is modified by cell membrane integrity, extracellular microarchitecture, active transport mechanisms, and microcirculation and detects molecular displacements at a cellular scale (in the order of μm). DWI can be incrementally sensitized to diffusion by altering the amplitude, duration, and spacing of magnetic field gradients; the degree of this weighting is determined by the b value, with values from s/mm 2 currently used in clinical practice. At relatively low b values (< s/mm 2), there is rapid signal loss in structures in which water mobility is relatively free (such as in fluid collections) or governed by flow (such as in vessels and ducts). This phenomenon, termed intravoxel incoherent motion, introduces a perfusional component into diffusion data. At higher b values (> 150 s/ mm 2), signal attenuation has a slower rate and occurs primarily due to diffusion within the extravascular space. The quantitative parameter apparent diffusion coefficient (ADC) is derived from the exponential attenuation of signal intensity between at least two b values. 54 RADIOLOGY & IMAGING

55 Restricted diffusion is depicted as bright foci in the index DWI series and dark foci in the corresponding ADC maps. DWI is inherently low in signal-to-noise ratio (SNR), which reduces as the b value increases. This results in a spatial resolution of ~20 mm3 when a singleshot echo-planar sequence with fat suppression is used. DWI has been incorporated into conventional abdominopelvic imaging protocols in oncology with short imaging times (< 5 minutes), good SNR, and robust performance against sources of artifact. Intrinsic susceptibility-weighted or BOLD MRI uses the slight increase in T2* caused by paramagnetic deoxyhemoglobin to reflect the oxygenation status of tissue immediately adjacent to perfused microvessels. However, blood flow, ph, carbon dioxide tension, and hematocrit can also affect T2* readings. The BOLD effect, measured on a T2* sequence (typically a gradient-echo sequence), can be quantified by plotting the natural log of signal intensity against the TE to derive tissue relaxivity (the power of the exponent is 1 / T2* = R2*). These R2* maps reflect the local concentration of deoxyhemoglobin. For the correct interpretation of intrinsic susceptibility-weighted MRI, the blood volume in the tissues of interest must also be known. Because the signal intensity change in intrinsic susceptibility-weighted MRI is low, augmentation techniques through breathing carbogen (5% CO2, 95% O2) or 100% oxygen are used to induce increased perfusion due to CO2 vasodilatory effects and increased oxygenation. Changes in R2* in response to such vasomodulation are temporally correlated with changes in tissue po2 [2]. However, the use of vasomodulation has a high rate of failure in human studies due to technical difficulties in gas delivery and patient distress. Without vasomodulation, the intrinsic susceptibility-weighted MRI signal does not robustly measure or correlate directly with po2 values but may still be useful for assessing differential areas of oxygenation. MRS derives its signal from the different resonant frequencies of protons within a molecule due to magnetic diatomic interactions within the molecular structure. Table 1: FIGO 2009 classification from literature background. RADIOLOGY & IMAGING 55

56 Materials and methods: Our study was performed between Febrauary 2016 and October 2016 on 78 patients, identified by a retrospective review of the records, who were diagnosed with and treated for endometrial carcinoma at Vellammal teaching hospital. Patients parallely studied & screening at Madurai medical college & KGS Hospital for screening endometrial carcinoma to include in sample size. Women in whom complete data were not available, as well as those who did not have an MRI and/or who did not undergo hysterectomy, were excluded. All patients underwent staging surgery including total hysterectomy and bilateral salpingooophorectomy. For suspicious cases, lymphadenectomy was performed. If the cervix was involved, a radical hysterectomy would be done. Compare with transvaginal sonography (TVS), hysteroscopy with directed biopsy (H+B) and MRI, we can know which one of them plays a dominant role in detecting the depth of myometrial invasion and cervical invasion. MRI was acquired with 1.5 T system and phased-array pelvic coil. Pelvic MRI examination was composed of T2-weighted images, T1-weighed images and dynamic contrastenhanced images at 3.0T. Based on previously published criteria [9], superficial (<50%) myometrial invasion was detected by disruption of the junctional zone and deep ( 50%) myometrial invasion was detected by a preserved stripe enhancing outer myometrial wall. Absent invasion was diagnosed when a clear and uninterrupted junctional. Cervical invasion was diagnosed when disruption of the low-signal intensity inner cervical stroma appearing in T2-weighted images or disruption of the cervical epithelium enhancement appearing in dynamic contrastenhanced images. Following blinded interpretation of the MRI, the pathologic findings were reviewed together with MRI and the pathologic finding was treated as the gold standard. TVS and H+B: Among 78 patients, 56 patients had a transvaginal sonography (TVS), 42 patients had a hysteroscopy with directed biopsy (H+B) and 50 patients had a dilatation and curettage. The records were reported by specialists, respectively. Statistical analysis Statistical analysis was performed by SPSS for windows The sensitivity, specificity and positive predictive value (PPV) and negative predictive value (NPV) were calculated. The comparisons were made between MRI and transvaginal sonography, MRI and hysteroscopy with directed biopsy, to identify the accuracy in detecting the depth of myometrial invasion and cervical invasion using a Chi-square test. Result: Among 78 patients that all had an MRI included in this study, the mean age was 54.6 years (range years) and 24 (24.5%) were premenopausal. The most common histological subtype was the endometrioid type detected in 87.8% (86) of the patients and the most common tumor grade was well differentiated type (G1) 59.2% (58). A total of 62 had a transvaginal sonography (TVS) and 48 patients had a hysteroscopy with directed biopsy (H+B). 56 RADIOLOGY & IMAGING

57 Part of data are presented in Table 2. In the surgicopathological report, in 65.3% (64/98), the depth of myometrial invasion was less than 50% and in 20.4% (20/98), there was an equal or greater than 50% involvement and 14 patients (14.29%) had no involvement of the myometrium. 14 out of 26 patients (53.85%) who did not have any myometrial invasion in the MRI report, had lower than 50% myometrial involvement in the final pathological findings. 4 out of 54 patients (7.41%) with less than 50% myometrial involvement in MRI ultimately had more than 50% myometrial involvement. In the evaluation of the deep myometrial invasion (more than 50%), the sensitivity, specificity, positive and negative predictive values and positive and negative likelihood ratios of MRI were 70.00%, 94.87%, 77.78%, 92.50%, 13.65, 0.316, respectively. 14 out of 26 patients (53.85%) who did not have any myometrial invasion in the TVS report, had lower than 50% myometrial invasion in the final pathological findings. Four out of 54 patients (7.41%) with less than 50% myometrial invasion in TVS ultimately had more than 50% myometrial invasion. Table 2 shows the correlation of myometrial involvement in MRI, TVS and pathology. According to the correlation of cervical invasion in MRI, TVS, hysteroscopy with directed biopsy (H+B) and the final pathology report, 86 out of 89 patients (96.63%) without cervical involvement in MRI did not have any cervical invasion in the surgicopthological report. 56 out of 57 patients (98.25%) without cervical involvement in TVS did not have any cervical invasion in the surgicopthological report. All patients without cervical involvement in H+B did not have any cervical invasion in the surgicopthological report. Figure 1 & 2: Advanced FIGO staging in endometrial carcinoma in USG RADIOLOGY & IMAGING 57

58 Table 3 shows the correlation of cervical invasion in MRI, TVS, H+B and pathology. Table 3, in detecting the cervical invasion, the sensitivity of MRI was lower than that of TVS, but the difference was not significant (P=0.807). Hysteroscopy with directed biopsy had a evidently higher sensitivity than MRI and TVS had. Due to the junction between the lower uterine segment and the endocervix is not clearly defined [13], MRI and TVS are not the appropriate tools for the description of cervical invasion. However, hysteroscopy is effective in collecting specimens under visual control from anywhere in the uterine cavity [7]. It is a pity that hysteroscopy cannot detect the tumor infiltrating to the cervical stroma, but only the cervical endometrium. Although someones [14] found TVS has high specificity and accuracy in predicting myometrial invasion and cervical invasion in patients with endometrial cancer, TVS makes patients uncomfortable. And Fotopoulou et al. reported that TVS may reliably be utilized for the preoperative assessment of tumor size, presence of ascites and adnexal metastases, but less reliable for the detection of cervical invasion [15]. Figure 3,4,5: shows dynamic contrast sequences showing endometrial carcinoma causing myometrial invasion. 58 RADIOLOGY & IMAGING

59 Discussion: MR Imaging Appearances Endometrial cancer is isointense relative to hypointense normal endometrium on unenhanced T1-weighted images and most commonly shows heterogeneous intermediate signal intensity relative to hyperintense normal endometrium on T2weighted images. Relative to normal myometrium, the tumor is mildly hyperintense on T2-weighted images. At conventional MR imaging, the depth of myometrial invasion is optimally depicted with T2-weighted sequences. In the previous version of the FIGO staging system, breach or interruption of the junctional zone was important for differentiating between tumors confined to the endometrial complex and those invading the inner layer of the myometrium. However, this finding may become less important now that confinement to the endometrial complex and inner myometrial invasion are both classified as stage IA. In postmenopausal women, there is thinning of the myometrium secondary to uterine involution, which can make accurate assessment of the depth of myometrial invasion challenging at conventional MR imaging. Other commonly reported pitfalls in assessing the depth of myometrial invasion include tumor extension into the cornua, myometrial compression from a polypoid tumor, poor tumor-tomyometrium contrast and the presence of leiomyomas or adenomyosis.morphologic imaging is of limited value in these cases, and the addition of diffusion-weighted and dynamic contrast-enhanced MR imaging sequences is extremely helpful in assessing the depth of myometrial invasion. The diagnostic accuracy of conventional MR imaging in this context ranges from 55% to 77% (17,22). Standard imaging is also significantly limited in its ability to help detect lymph node metastases. It relies on nodal size, shape, and internal architecture to help differentiate between benign and metastatic nodes, all of which features have been shown to be highly variable predictors of nodal involvement (14-22). Added Value of Dif- fusion-weighted and Dynamic Contrast-enhanced: MR Imaging Dynamic contrast-enhanced MR imaging was first shown to improve the staging accuracy of MR imaging for endometrial cancer in the early 1990s.Differential enhancement within the endometrial cavity can allow tumor to be distinguished from blood products and debris (16,17). Endometrial tumors enhance earlier than does normal endometrium after the administration of intravenous contrast medium, which aids in the detection of small tumors confined to the endometrial complex. Normal myometrium enhances intensely compared with hypointense endometrial tumor.maximum contrast between hyperintense myometrium and hypointense endometrial tumor occurs seconds after contrast medium administration, and this is the most important phase for accurate assessment of the depth of myometrial invasion. Delayedphase images obtained 3 4 minutes after contrast medium administration are useful in evaluating for cervical stromal invasion (FIGO stage II). The presence of an intact enhancing cervical mucosa excludes stromal invasion. The combination of dynamic contrast-enhanced and T2-weighted MR imaging offers a one-stop examination for endometrial cancer staging and is recommended by the European Society for Urological Research in its guidelines for endometrial cancer staging (22). Dynamic contrast-enhanced images, when read together with T2-weighted images, have a diagnostic accuracy of up to 98% for assessing myometrial invasion (12,14,16,17,22). However, there is some controversy in the literature regarding the added value of dynamic contrast-enhanced MR imaging for overall FIGO staging: Although the majority of published studies have shown an RADIOLOGY & IMAGING 59

60 improvement in staging accuracy with dynamic contrast-enhanced MR imaging, some authors have found no benefit (14,16,17,22). Diffusion-weighted MR imaging is a functional imaging technique that displays information about water mobility, tissue cellularity, and the integrity of the cell membranes (16 18). Endometrial cancer exhibits impeded diffusion compared with surrounding tissue, manifesting with high signal intensity on diffusion-weighted MR images and low signal intensity on ADC maps, which provide a quantitative measure of water diffusion. Diffusion-weighted MR images should always be reviewed with their corresponding ADC maps and other anatomic images to avoid pitfalls such as T2 shinethrough (apparent high signal intensity of a lesion due to the long T2). Impeded diffusion can also occur in areas of retained mucus such as an obstructed endometrial cavity, and cross-referencing with anatomic images can help differentiate this finding from tumor. In clinical practice, diffusion-weighted MR imaging should be performed with at least two b values: a low value of 0 or 50 sec/mm2 and a high value of sec/mm2 (13,40,42). The higher the b value, the less background signal and T2 shinethrough will be present on the images. We have found a high b value of 800 sec/mm2 to be optimal and use this b value for axial oblique diffusionweighted MR imaging. We also use a third b value (500 sec/mm2) for sagittal imaging in the belief that it aids in assessing myometrial invasion and cervical stromal extension. The added value of diffusion-weighted MR imaging for endometrial cancer staging is less well established than that of dynamic contrast-enhanced MR imaging; however, the diagnostic accuracy of diffusion-weighted MR imaging for assessing myometrial invasion ranges from 62% to 90%.In a recent prospective study by Rechichi et al,the staging accuracy of diffusion-weighted MR imaging was superior to that of dynamic contrast-enhanced MR imaging and had a higher level of interobserver agreement. The authors suggested that diffusion-weighted MR imaging could replace dynamic contrast-enhanced MR imaging for endometrial cancer staging, offering the potential advantages of reduced scanning time and obviation of the intravenous administration of gadolinium-based contrast medium. Diffusion-weighted imaging can also provide quantitative information in the form of ADC values. For calculation of ADC values, six or more b values should be used to ensure accurate quantification of impeded diffusion.malignant tumors have significantly lower ADC values than benign lesions such as endometrial polyps and submucosal leiomyomas. Caution must be used because tumor necrosis in poorly differentiated lesions may also have high ADC values (18,21). Impeded diffusion can occur in any normal anatomic structure with a high cellular density. Reactive lymph nodes may have high signal intensity at diffusion-weighted MR imaging due to their high cellular density, and impeded diffusion has been reported in both benign and metastatic lymph nodes (12,14). There are conflicting reports in the literature regarding the detection of lymph node metastases at diffusion-weighted MR imaging of gynecologic malignancies. Lin et al demonstrated that 3.0-T MR imaging had a greater sensitivity in the detection of nodal metastases in patients with endometrial and cervical cancer. The authors reported that ADC values for malignant nodes were significantly lower than those for benign nodes, and that the use of nodal ADC values combined with lymph node size yielded a sensitivity of 83% for assessing the presence of nodal malignancy.in contrast, Nakai et al used 1.5-T MR imaging to evaluate nodal ADC values in gynecologic malignancies and were unable to differentiate benign from malignant lymph nodes. However, they did find that diffusion-weighted MR imaging was useful in the detection of lymph nodes. Functional MRI for Staging Endometrial Cancer The use of DCE-MRI in the sagittal plane improves the ability to assess the depth of myometrial invasion by increasing contrast resolution between tumor and myometrium (sensitivity, 87 92%; specificity, 91%). (Fig. 3). Although early studies suggested that DCE-MRI has a better overall staging accuracy than DWI because of poorer spatial resolution with DWI improvements in DWI technique now indicate that its performance may well be superior, particularly if exploiting increased SNR at 1.5 T. Comparison of T2-weighted imaging, DCE-MRI, and DWI scored individually gave sensitivities and specificities of (92.3% and 76.5% vs 69.2% and 61.8%, vs 84.6% and 70.6%, respectively) [50]. Using all three (T2-weighted imaging, DCE-MRI, and DWI) techniques together has proven better than DCE-MRI alone or DCE-MRI with T2weighted MRI (p = 0.001), with T2-weighted imaging with DWI 60 RADIOLOGY & IMAGING

61 better than T2-weighted imaging with DCE-MRI (p = 0.001). Another recent retrospective study showed that DWI had higher staging accuracy and interobserver agreement than DCE-MRI; a particular advantage is evident if adenomyosis is present. However, the potential of quantitative DCE-MRI has not been Conclusion: investigated in these studies. Diffusion-tensor imaging has been explored in ex vivo specimens for identifying myometrial invasion but remains unexploited in vivo because of poor SNR and presence of artifacts. ADC has been reported lower in endometrial adenocarcinomas with cervical extension compared with primary cervical carcinomas However, because the endometrial cancers were by definition a higher stage and therefore likely more aggressive, it is not clear whether this difference is a function of tumor aggressiveness rather than site of origin Functional MRI is becoming established in the evaluation of gynecologic malignancies. Parameters derived from functional MRI may be used to examine tumor vascularity, tissue microarchitecture, hypoxic status, and metabolic profile, features that may be exploited for tumor characterization, staging, or as predictive or response biomarkers. The improved tumor-to-normal tissue contrast on DWI in uterine malignancies improves tumor detection and targeted biopsy and has potential to improve staging, although data from trials is awaited. In endometrial cancer, the utility of DCE-MRI for staging is established, whereas both DCEMRI and DWI improve detection of early recurrence in uterine malignancy. Therefore, surveillance imaging protocols should include T2-weighted imaging and DWI with the addition of DCE-MRI in cases in which further characterization of nodular lesions is needed. The utility in surveillance of ovarian cancer remains limited to cases in which the serum biomarker CA-125 is noncontributory. In assessment of treatment response, it is essential to select the appropriate imaging biomarker for the cellular process being examined, for example, DCE- MRI would be the biomarker of choice for assessing response to an antiangiogenic drug, whereas DWI would be more appropriate to evaluate the necrosis expected in response to a traditional chemotherapeutic agent. Multiparametric analysis potentially circumvents this by reporting simultaneously on different aspects of the tumor and quantifying the differential response to treatment. In our experience, however, it is important to select appropriate parameters that answer the clinical question because multiparametric data acquisition and analysis can be a time-consuming process. Techniques such as DCEMRI for example, would only be required to answer specific end points on tumor vascularity, avoiding the unnecessary use of contrast agents and the associated risks of nephrogenic systemic fibrosis. Functional MR techniques are quantitative and require robust protocols both for data acquisition and analysis. Attention to detail in quality assurance will ensure their viability in a multicenter trial market in which it is necessary to produce measurements that are reliable and that meet national and international standards. References: 1. National Cancer Institute. Cancer Stat Fact Sheets: sorpus and uterus, NOS. Bethesda, Md: National Cancer Institute, Jemal A, Siegel R, Xu J, Ward E. Cancer statistics, CA Cancer J Clin 2010;60(5): Bray F, Dos Santos Silva I, Moller H, Weiderpass E. Endometrial cancer incidence trends in Europe: underlying determinants and prospects for prevention. Cancer Epidemiol Biomarkers RADIOLOGY & IMAGING Prev 2005;14(5): Rha SE, Byun JY, Jung SE, et al. CT and MRI of uterine sarcomas and their mimickers. AJR Am J Roentgenol 2003;181(5): Sala E, Wakely S, Senior E, Lomas D. MRI of malignant neoplasms of the uterine corpus and cervix. AJR Am J Roentgenol 2007;188(6): Creasman W. Revised FIGO staging for carcinoma of the endometrium. Int J Gynaecol Obstet 2009; 105(2): Coakley FV, Choi PH, Gougoutas CA, et al. Peritoneal metastases: detection with spiral CT in patients with ovarian cancer. Radiology 2002; 223: de Bree E, Koops W, Kroger R, van Ruth S, Witkamp AJ, Zoetmulder FA. Peritoneal carcinomatosis from colorectal or appendiceal origin: correlation of preoperative CT with intraoper- 61

62 ative findings and evaluation of interobserver agreement. J Surg Oncol 2004; 86: Jacquet P, Jelinek JS, Steves MA, Sugarbaker PH. Evaluation of computed tomography in patients with peritoneal carcinomatosis. Cancer 1993; 72: Low RN, Barone RM, Lacey C, Sigeti JS, Alzate GD, Sebrechts CP. Peritoneal tumor: MR imaging with dilute oral barium and intravenous gadolinium-containing contrast agents compared with unenhanced MR imaging and CT. Radiology 1997; 204: Bernardin L, Dilks P, Liyanage S, Miquel ME, Sahdev A, Rockall A. Effectiveness of semi-quantitative multiphase dynamic contrast-enhanced MRI as a predictor of malignancy in complex adnexal masses: radiological and pathological correlation. Eur Radiol 2012; 22: Thomassin-Naggara I, Bazot M, Darai E, Callard P, Thomassin J, Cuenod CA. Epithelial ovarian tumors: value of dynamic contrast-enhanced MR imaging and correlation with tumor angiogenesis. Radiology 2008; 248: Thomassin-Naggara I, Balvay D, Aubert E, et al. Quantitative dynamic contrast-enhanced MR imaging analysis of complex adnexal masses: a preliminary study. Eur Radiol 2012; 22: Katayama M, Masui T, Kobayashi S, et al. Diffusion-weighted echo planar imaging of ovarian tumors: is it useful to measure apparent diffusion coefficients? J Comput Assist Tomogr 2002; 26: Ye T, Zeng MS, Rao SX. Comparative Study between MRI Features and Pathology in FIGO Stage I and II Endometrial Carcinoma. The Chinese-German Journal of Clinical Oncology 2006; Sala E, Crawford R, Senior E, Shaw A, Simcock B, Vrotsou K, Palmer C, Rajan P, Joubert I, Lomas D. Added Value of Dynamic ContrastEnhanced Magnetic Resonance Imaging in predicting Advanced Stage Disease in Patients With Endometrial Carcinoma. Int J Gynecol Cancer 2009; 19: Pecorelli S. Revised FIGO staging for carcinoma of the vulva, cervix, and endometrium. Int J Gynaecol Obstet 2009; 105: [4] Siegel R, Naishadham D, Jemal A. Cancer Statistics, CA Cancer J Clin 2013; 63: Nagar H, Dobbs S, McClelland HR, Price J, McCluggage WG, Grey A. The diagnostic accuracy of magnetic resonance imaging in detecting cervical involvement in endometrial cancer. Gynecol Oncol 2006; 103: Wang JP, Yu TL, Bai RJ, Sun HR, Zhao X, Li YJ. The Value of the Apparent Diffusion Coefficient in Differentiating Stage IA Endometrial Carcinoma From Normal Endometrium and Benign Diseases of the Endometrium: Initial Study at 3-T Magnetic Resonance Scanner. J Comput Assist Tomogr 2010; 34: Bedner R, Rzepka-Gorska I. Hysteroscopy with directed biopsy versus dilatation and curettage for the diagnosis of endometrial hyperplasia and cancer in perimenopausal women. Eur J Gynaecol Oncol 2007; 28: Shen SH, Chiou YY, Wang JH, Yen MS, Lee RC, Lai CR, Chang CY. Diffusion-weighted singleshot echo-planar imaging with parallel technique in assessment of endometrial cancer. AJR Am J Roentgenol 2008; 190: RADIOLOGY & IMAGING

63 128 Slice Multidetector Cardiac CT Versus Echocardiography Correlation for Three Dimensional Volume Analysis of Left Atrium Md Ameen MD, N.S.Mani MD Department of Radiodiagnosis, Vellammal Teaching Hospital, Madurai, Tamil Nadu, India. Objective: CT & MRI To prospectively assess the relationship between the two different measurement methods for the evaluation of left atrial (LA) volume using cardiac multidetector computed tomography (MDCT) and to compare the results between cardiac MDCT and echocardiography. Materials and Methods: Thirty-five patients (20 men, 15 women; mean age, 60 years) underwent cardiac MDCT angiography for coronary artery disease. The LA volumes were measured using two different methods: the two dimensional (2D) length-based (LB) method measured along the three-orthogonal planes of the LA and the 3D volumetric threshold-based (VTB) method measured according to the threshold 3D segmentation of the LA. The results obtained by cardiac MDCT were compared with those obtained by echocardiography. Results: The LA end-systolic and end-diastolic volumes (LAESV and LAEDV) measured by the 2D-LB method correlated well with those measured by the 3DVTB method using cardiac MDCT (r = 0.763, r = 0.786, p = 0.001). However, there was a significant difference in the LAESVs between the two measurement methods using cardiac MDCT (p < 0.05). The LAESV measured by cardiac MDCT correlated well with measurements by echocardiography (r = 0.864, p = 0.001), however with a significant difference (p < 0.01) in their volumes. The cardiac MDCT overestimated the LAESV by 22% compared to measurements by echocardiography. Conclusion: A significant correlation was found between the two different measurement methods for evaluating LA volumes by cardiac MDCT. Further, cardiac MDCT correlates well with echocardiography in evaluating the LA volume. However, there are significant differences in the LAESV between the two measurement methods using cardiac MDCT and between cardiac MDCT and echocardiography. Keywords- MDCT, Echo Cardiography, Left atrium, Angiography. RADIOLOGY & IMAGING 63

64 INTRODUCTION: The size of the left atrium (LA) is considered to be an important prognostic factor of cardiovascular morbidity and mortality in patients with cardiovascular disease (1-4). The prognosis for atrial fibrillation is associated with the LA volume. Therefore, evaluation of the LA volume is very important during the follow-up period in order to assess the results of catheter ablation treatment in patients with atrial fibrillation (5, 6). Echocardiography has been the most commonly used diagnostic modality for assessing LA volume in daily clinical situations. However, volume measurement using echocardiography may be difficult to obtain as well as inaccurate due to the complex shape of the LA (7). Furthermore, echocardiography underestimates the LA volume compared to angiography (8), magnetic resonance imaging (MRI) (9), or multidetector computed tomography (MDCT) (10, 11). Cardiac MDCT has been introduced as a promising modality for coronary artery imaging (11-14). Imaging data are continuously acquired throughout the entire cardiac cycle under retrospective electrocardiographic (ECG) gating. Therefore, we can select the appropriate phases for the maximum and minimum LA volumes at the endsystole and end-diastole based on the ECG (09). However, the measurement methods for the evaluation of LA volumes and functions using cardiac MDCT have rarely been discussed. Previous studies reported that the diameter-length method using cardiac MRI, referred to as the two dimensional (2D) length-based (LB) method in this study, would be available for assessing LA volumes based on the geometrical assumptions suggested by trans-thoracic echocardiography (TTE) (9, 10). These studies, however, have not established how the 2D LB method, using cardiac MDCT or MRI, accurately measures the LA volumes when compared to results obtained from the 3D volumetric threshold-based (VTB) method which allows direct measurement without geometrical assumptions of the LA volumes. Therefore, the purpose of this study is to prospectively assess the relationship between the 2D LB method and the 3D VTB method for the evaluation of LA volumes and function using ECG-gated cardiac MDCT. We will also compare the results of the 3D VTB method using cardiac MDCT to results obtained using ECG. MATERIALS AND METHODS: Patients Preparation This study was approved by the respective Institutional Review Boards. Thirty-five patients who underwent cardiac MDCT as a screening examination for coronary artery disease were included in this prospective study. Twenty of the 35 patients were men, and 15 were women. Their mean age at the time of the examination was 60 years (age range; years). Period of study from February 2016 to October Ethical committee approval obtained from Vellammal medical college. An additional ECG was performed to assess the LA volumes. The mean period of time between cardiac MDCT and ECG was 6.8 days (day range; 2-13 days). This study was undertaken after informed consent was obtained from the patients for cardiac MDCT and ECG. Multidetector CT Scanning Protocol and Image Reconstruction: Cardiac MDCT was performed using a 128-MDCT scanner (GE WIPRO 128 Advanced Medical Solutions, Forchheim, Germany). Patients with a heart rate of more than 65 beats per minute (bpm) were given an oral b-blocker (40 mg propranolol hydrochloride; Pranol, Dae Woong, Seoul, Korea) one hour before examination to reduce their heart rate. With the patient in the supine position, cardiac MDCT was performed in the craniocaudal direction during a single breath-hold at end-inspiratory suspension. A total of 65 ml of contrast medium (Optiray 350; Tyco Healthcare, Kanata, Canada) was administered intravenously at a rate of 4 ml/sec followed by 50 ml of normal saline at a rate of 5 ml/sec using a power injector (Stellant, Medrad, Indianola, PA). Imaging was performed using a real-time bolus tracking technique in which the region of interest (ROI) was located at the ascending aorta. The scans were started 5 seconds after a trigger threshold of 100 HU was reached. The duration of the breath-hold ranged from 10 to 14 seconds, with an average breath-hold of 12.3 seconds. The breath-hold was achieved by all patients and ECG was recorded for each patient simultaneously. The scanning parameters were as follows: RADIOLOGY & IMAGING

65 msec gantry rotation time, 120 kv, 700 mas, 0.6 mm slice collimation, 3 mm slice width, and 2.4 mm table feed per rotation. The estimated radiation dose under the ECG gated modulation technique ranged from 8 to 12 msv depending on the scanning range and the patient s body weight. Imaging reconstruction was performed on the scanner s workstation using commercially available software. We used the partial scan algorithm, which provided a heart-ratedependent temporal resolution between 93 and 185 msec from a 370 msec gantry rotation. The reconstruction parameters were as follows: a 0.75 mm slice thickness, 0.5 mm increment, pixel image matrix, medium smooth kernel (B25f), and a cm field of view. In order to obtain the maximum and minimum sizes of the LA, we reconstructed the image sets at the maximum systolic constriction and diastolic relaxation phases based on retrospective ECG triggering; the maximum systolic constriction phase was determined when the reconstruction window was located halfway in the ascending T wave on ECG. Whereas, the end-diastolic relaxation phase was determined when the reconstruction window was located at the start point of the QRS complex on ECG (15). The image sets were then transferred to a separate workstation (GE,Medical Solution) for analysis. Multidetector CT Data Analysis: Two radiologists independently evaluated the LA volumes and function using commercially available software (3D Volume Measurement, Leonardo, Siemens Medical Solution, Germany). They were blinded to the results of ECG. Left atrial volumes were measured using two different methods with retrospective ECG-gated cardiac MDCT. The methods were the 2D LB and 3D VTB methods. For the 2D LB method, the size of the LA was measured along the three-orthogonal planes (transverse, anterior-posterior, and longitudinal) based on the techniques suggested by Ho et al. (11) and Jayam et al. The transverse diameter of the LA was defined as the distance between the midpoint of the pulmonary veins on the right and left sides of the atrium using an oblique axial image. The anterior-posterior and longitudinal (cranio-caudal) diameters were measured at the midpoint of the transverse diameter using the oblique axial and sagittal images of the LA (Fig. 1). The oblique axial images were obtained when four pulmonary veins were connected to the LA on one image plane. The volume of the LA was assessed using the following equation: LA volume = π TD AP/2 LD/2, where TD is the transverse diameter, AP is the anterior-posterior diameter, and LD is the longitudinal diameter For the 3D VTB method, the endocardial contours of the LA were semi-automatically traced on the axial slices using the analysis software. We applied the lowest value of CT attenuation to cover the entire contrast-enhanced LA cavity as well as to eliminate the pericardial fatty tissue within an ROI. The lowest values of CT attenuation were determined when the LA cavity was completely included in the LA volume. The atrial appendage was excluded from the LA volume. We also excluded the pulmonary vein confluences from the volume calculations (Fig. 2). Statistical Analysis: A Pearson s correlation and Bland-Altman analysis were performed to determine the correlation and limits of agreement for the LA volumes and function between the 2D LB and the 3D VTB methods of cardiac MDCT. A linear regression and Bland-Altman analysis were used to determine the correlation and limits of agreement for the LA volumes between the 3D VTB method of cardiac MDCT and ECG. We used a Wilcoxon s signed rank test to evaluate the statistical significance of the differences in the LA volumes and function between the 2D LB and the 3D VTB methods of cardiac MDCT as well as between the 3D VTB method of cardiac MDCT and ECG. A p-value of less than 0.05 was considered to be statistically significant. The statistical analyses were performed using the SPSS software (version , Statistical Package for the Social Sciences, Chicago, IL). The inter-observer variability (Var) for the LA volume, measured by cardiac MDCT, was assessed using the following equation: Var = (LA volume1 - LA volume2) / (LA volume1 + LA volume2) 0.5. RADIOLOGY & IMAGING 65

66 RESULTS: The mean heart rate of the patients during the scan ranged from 46 to 93 bpm (mean, 63 bpm). Seven patients with a heart rate of more than 65 beats per minute were given oral beta -blockers (mean, 80 bpm). Cardiac MDCT allows for a clear delineation of the endocardial contours of the LA. Although minor stair-step artifacts were visualized in some patients with a heart rate greater than 70 bpm, there were no difficulties in evaluating the LA volumes. These artifacts were more frequent during the end-systolic constriction phase. The measurement data using cardiac MDCT are summarized in Table 1. The LA end-systolic (73 ± 20 ml) and end-diastolic (46 ± 12 ml) volumes (LAESV and LAEDV) measured by cardiac MDCT using the 2D LB method correlated well with those measured by cardiac MDCT using a 3D VTB method (LAESV = 79 ± 17 ml, r= 0.763, p= 0.001; LAEDV = 47 ± 12 ml, r= 0.786, p= 0.001). The LA ejection fraction (37 ± 8%) measured by cardiac MDCT and using the 2D LB method showed a moderate correlation with the measurement by cardiac MDCT using a 3D VTB method (41 ± 7 %, r= 0.489, p= 0.003). There were significant differences in the mean LAESV and LA ejection fraction (p< 0.05). However, there was no significant difference in the LAEDV between the 2D LB method and the 3D VTB method of cardiac MDCT (p> 0.05) (Table 1). Using the modified biplane Simpson s method, the mean LAESV (79 ± 17 ml), measured by cardiac MDCT using the 3D VTB method, showed a good correlation with the volume (62 ± 15 ml) measured by ECG (r= 0.864, p= 0.001) (Table 2). Table 1: Comparison of Left atrial volume by 2D length based and 3D volume threshold method. Table 2: Comparison of left atrial volume between 3D volume threshold and Echocardiography. There were significant differences in the mean LAESV between cardiac MDCT using the 3D VTB method and ECG using the modified biplane Simpson s method (p< 0.01). Cardiac MDCT significantly overestimated of the LAESV of 17 ± 9 ml (22%) when compared to ECG (Fig. 5B). The inter-observer variability for the LA volumes, measured by cardiac MDCT using the 2D LB method was 7.6% for the LAESV and 1.2% for the LAEDV. The variability for the LA volumes measured by cardiac MDCT using the 3D VTB method was 7.4% for the LAESV and 3.2% for the LAEDV. 66 RADIOLOGY & IMAGING

67 Fig 1 (A,B): Left atrial volume measurement using 2D length based method. Fig 2 (A,B): Measurement of left atrial volume using 3D threshold based method. Fig 3 ( A,B): Measurement of left atrial volume by Modified Biplane Simpson rule method ( echo) RADIOLOGY & IMAGING 67

68 DISCUSSION: This study showed that the LAESVs and end-laedvs measured by cardiac MDCT using the 2D LB method correlated well with those measured by cardiac MDCT using the 3D VTB method. In addition, the LA ejection fraction measured by cardiac MDCT using the 2D LB method showed a moderate correlation with measurements by cardiac MDCT using the 3D VTB method. The LAESV measured by cardiac MDCT using the 3D VTB method correlated well with that measured by ECG. Cardiac MDCT overestimated the LA volume by 22% compared to ECG (p< 0.01). In clinical situations in which it is necessary to evaluate the LA size in patients with cardiac arrhythmia, ECG has been the most commonly used diagnostic tool for making these measurements (11, 12). When various methods for assessing the LA volume using ECG are used, the American Society of Echocardiography recommends using a quantification method for measuring the LA volumes by biplane ECG either using Simpson s rule or the area-length method (07). The advantages of ECG include a high temporal resolution and short acquisition time. However, a narrow echo window and geometrical assumptions limit the accuracy of ECG. Some studies have recently reported that cardiac MDCT could be useful in evaluating cardiac function and a myocardial mass without additional radiation exposure in patients with suspected coronary artery disease (04, 05, 06). Specifically, the 3D VTB method provides the potential to easily measure the LV volume and function. This could be a simpler, less user-dependant, and timesaving method compared to the 2D area-based method after short-axis reconstruction of the LV (06, 07). A shorter gantry rotation time, lower collimation, and an increase in the number of detector rows have improved the temporal and spatial resolution of cardiac MDCT. These improvements make it more suitable for the assessment of cardiac volumes and function. Kircher et al. (10) reported that LA volume measured by cine CT showed an excellent correlation with ECG measurements. However, cine CT overestimated the LA volume by 23% compared to ECG. In our study using a 64-slice MDCT scanner, cardiac MDCT using the 3D VTB method overestimated the LAESV by 22% compared to ECG using the modified biplane Simpson s rule. The recent study also showed that ECG following the biplane modified Simpson s rule underestimated the maximum LA volume by 35% compared to cardiac MDCT using new 3D reconstruction software (11). One reason for the differences of ESV between cardiac MDCT and ECG may appear to be the administration of b-blocker prior to the CT examination. Some previous reports have clearly demonstrated that the application of b-blocker results in a significant reduction heart rate, ejection fraction, cardiac contractility and cardiac index, whereas ESV and EDV increase (10). The measurement of LA volume is difficult due to its complex shape. Multiple methods which use various geometric assumptions about the atrial shape have been developed for assessing LA volume using ECG (11,). Previous studies reported that the 2D LB method using MR imaging would be helpful in evaluating the LA volumes by using the size measurements of the LA along the three-orthogonal (transverse, anterior-posterior, and longitudinal) planes (09). However, to the best of our knowledge, the relationship of the LA volume measurements between the 2D LB and the 3D VTB methods of cardiac MDCT have not been previously studied. The 2D LB method analyzes LA volumes under the assumption that the LA resembles the shape of an ovoid cylinder. The 3D VTB method allows direct volume measurement of the LA without geometrical assumptions because 3D images can be reconstructed by excellent volumetric acquisition of cardiac MDCT with the isotropic voxel (09). In our study, the LA volume measurements using cardiac MDCT showed a good correlation between the 2D LB and the 3D VTB methods. The measured LA volumes were relatively consistent using the two measurement methods of cardiac MDCT. These results show that the 2D LB method for LA volume measurement provides similar results to the 3D VTB method when the LA appendage and the pulmonary vein confluences are excluded. However, there were significant differences between the two methods of cardiac MDCT in the measurement of LAESVs. The differences in these measurements may be related to the limited temporal resolution which is poorer in systole than in diastole. Ritchie et al, reported that a temporal resolution of approximately 20 ms was needed in order to completely avoid motion artifacts in cardiac imaging. Thus, the limited temporal resolution used in our study may have an adverse effect on our ability to measure LA volumes at 68 RADIOLOGY & IMAGING

69 the end-systolic phase compared to the end-diastolic phase. With the introduction of dual-source CT, the increased temporal resolution of 83 ms improves the assessment of cardiac function in CT. Recent study shows the dual-source CT offers the possibility to quantify left ventricular function from coronary CT angiography datasets with sufficient diagnostic accuracy with MRI as standard of reference. A stairstep artifact can affect the ventricular function evaluations in the systolic phase, but not in the diastolic phase. For both measurement methods, the interobserver variability was higher in the evaluation of the LAESV than in the evaluation of the LAEDV. Our study has some limitations. First, we did not evaluate the LA volumes in sick patients or patients with arrhythmias who could increase the error range in the LA volume assessments. Therefore, further study will be needed for the results to be generalized in sick patients or patient with arrhythmias. Second, the proper values of CT attenuation were not considered in the evaluation of the LA volume using cardiac MDCT with the 3D VTB method. Inhomogeneous enhancement of the LA cavity may influence the LA volume assessment using the 3D VTB method. Third, we did not compare the results measured by cardiac MDCT with those acquired by cardiac MR imaging, which is generally accepted as the gold standard for evaluation of ventricular function. However, MR imaging still has limitations in that it provides the 2D images of the complex structures of the LA including the pulmonary veins and atrial appendage, which results in a difficulty to measure the LA volumes. Therefore, a comparison study between cardiac MDCT and cardiac MR imaging or further, a study to guide the standard measurement methods with cardiac MR imaging will be performed for the evaluation of the LA volumes. Finally, we used 64slice MDCT with a 370 ms gantry rotation time which provided limited temporal resolution and caused the measurement errors for the LA volumes. Therefore, further studies in the evaluation of the LA volumes should be performed using a recent ultra-high channel MDCT with above 128-slice detectors as well as shorter temporal resolution in the future. Conclusion: There is good correlation between the two different measurement methods for evaluation of the LA volumes using cardiac MDCT. In addition, cardiac MDCT correlates well with ECG in evaluating the LA volumes. However, there are significant differences in the LAESV between the two measurement methods using cardiac MDCT and between cardiac MDCT and ECG. Cardiac MDCT may be useful in evaluating the LA volume and function using either the 2D LB method or using the 3D VTB method in patients without arrhythmias. However, there are fewer measurement errors in the end-diastolic phase than in the end-systolic phase, regardless of which specific measurement method of cardiac MDCT is used. References: RADIOLOGY & IMAGING 1.Beinart R, Boyko V, Schwammenthal E, Kuperstein R, Sagie A, Hod H, et al. Long-term prognostic significance of left atrial volume in acute myocardial infarction. J Am Coll Cardiol 2004;44: Kizer JR, Bella JN, Palmieri V, Liu JE, Best LG, Lee ET, et al. Left atrial diameter as an independent predictor of first clinical cardiovascular events in middle-aged and elderly adults: the Strong Heart Study (SHS). Am Heart J 2006;151: Rossi A, Cicoira M, Zanolla L, Sandrini R, Golia G, Zardini P, et al. Determinants and prognostic value of left atrial volume in patients with dilated cardiomyopathy. J Am Coll Cardiol 2002;40: Tsang TS, Barnes ME, Bailey KR, Leibson CL, Montgomery SC, Takemoto Y, et al. Left atrial volume: important risk marker of incident atrial fibrillation in 1655 older men and women. Mayo Clin Proc 2001;76: Feinberg MS, Waggoner AD, Kater KM, Cox JL, Lindsay BD, Perez JE. Restoration of atrial function after the maze procedure for patients with atrial fibrillation. Assessment by Doppler echocardiography. Circulation 69

70 1994;90:II285-II Yashima N, Nasu M, Kawazoe K, Hiramori K. Serial evaluation of atrial function by Doppler echocardiography after the maze procedure for chronic atrial fibrillation. Eur Heart J 1997;18: Jessurun ER, van Hemel NM, Kelder JC, Defauw JA, Brutel de la Rivie`re A, Ernst JM, et al. The effect of maze operations on atrial volume. Ann Thorac Surg 2003;75: Bartunek J, Vantrimpont PJ, De Bruyne B. Left atrial-volume determination by echocardiography. Validation by biplane angiography in the setting of mitral balloon valvuloplasty. Int J Card Imaging 1994;10: Rodevan O, Bjornerheim R, Ljosland M, Maehle J, Smith HJ, Ihlen H. Left atrial volumes assessed by three- and twodimensional echocardiography compared to MRI estimates. Int J Card Imaging 1999;15: Kircher B, Abbott JA, Pau S, Gould RG, Himelman RB, Higgins CB, et al. Left atrial volume determination by biplane twodimensional echocardiography: validation by cine computed tomography. Am Heart J 1991;121: Christiaens L, Lequeux B, Ardilouze P, Ragot S, Mergy J, Herpin D, et al. A new method for measurement of left atrial volumes using 64-slice spiral computed tomography: comparison with two-dimensional echocardiographic techniques. Int J Cardiol 2009;131: Achenbach S, Ulzheimer S, Baum U, Kachelriess M, Ropers D, Giesler T, et al. Noninvasive coronary angiography by retrospectively ECG-gated multislice spiral CT. Circulation 2000;102: Raff GL, Gallagher MJ, O Neill WW, Goldstein JA. Diagnostic accuracy of noninvasive coronary angiography using 64-slice spiral computed tomography. J Am Coll Cardiol 2005;46: Mollet NR, Cademartiri F, van Mieghem CA, Runza G, McFadden EP, Baks T, et al. High-resolution spiral computed tomography coronary angiography in patients referred for diagnostic conventional coronary angiography. Circulation 2005;112: Ho SY, Sanchez-Quintana D, Cabrera JA, Anderson RH. Anatomy of the left atrium: implications for radiofrequency ablation of atrial fibrillation. J Cardiovasc Electrophysiol 1999;10: Jayam VK, Dong J, Vasamreddy CR, Lickfett L, Kato R, Dickfeld T, et al. Atrial volume reduction following catheter ablation of atrial fibrillation and relation to reduction in pulmonary vein size: an evaluation using magnetic resonance angiography. J Interv Card Electrophysiol 2005;13: Lang RM, Bierig M, Devereux RB, Flachskampf FA, Foster E, Pellikka PA, et al. Recommendations for chamber quantification. Eur J Echocardiogr 2006;7: Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;1: Ujino K, Barnes ME, Cha SS, Langins AP, Bailey KR, Seward JB, et al. Two-dimensional echocardiographic methods for assessment of left atrial volume. Am J Cardiol 2006;98: Juergens KU, Seifarth H, Maintz D, Grude M, Ozgun M, Wichter T, et al. MDCT determination of volume and function of the left ventricle: are short-axis image reformations necessary.ajr Am J Roentgenol 2006;186:S371-S RADIOLOGY & IMAGING

71 Case presentation A Rare Case Of Hemangiopericytoma Of Lower Face & Neck CM Tempany MD, FA Masoud MD, FF Marshall MD Abstract: Hemangiopericytoma (HPC) is an exceedingly rare tumor of uncertain malignant potential. Approximately 300 cases of HPC have been reported since Stout and Murray described HPCs as vascular tumors arising from Zimmerman s pericytes in After further characterization, the WHO reclassified HPC as a fibroblastic/myofibroblastic tumor. Long term follow up is mandatory because the histologic criteria for prediction of biologic behavior are imprecise. There are reports of recurrence and metastasis many years after radical resection. The head and neck incidence is less than 20%, mostly in adults. We report herein a case of HPC resected from the neck of a 64-year-old woman, who presented in our department with a painless left-sided lower face & neck mass. The mass was well circumscribed, mobile and soft during the palpation. The skin over the tumor was intact and normal. Clinical diagnosis at this time was carcinoma cheek. A neck computer tomography scan showed a large submucosal mass in the neck, which extended in the muscular sites. The tumor was completely removed by wide surgical resection. During surgery we found a highly vascularised tumor. The histopathologic examination revealed a cellular, highly vascularized tumor. The diagnosis was that of solitary fibrous tumor, cellular variant, with haemangiopericytoma-like features. The patient had normal postoperative course of healing. Fig 1: Vascular enhancement of tumour seen in delayed axial sections. Key words: HPC- hemangiopericytoma, SFT-solitary fibrous tumour RADIOLOGY & IMAGING 71

72 Introduction: Solitary fibrous tumor was first described by Wagner in 1870 [1]. It develops from the cells lining capillaries, pericytes which are small, oval or spindle-shaped cells lining capillaries [2]. They were first described in 1923 by Zimmermann, as specialized cells normally present around amphibian and vertebrate capillaries; they were thought to be modified smooth-muscle cells [3]. Discussion: Epidemiology In 1942 Stout and Murray described nine tumors which were composed of capillary blood vessels with one or more layers of rounded cells arranged about them which cannot be called glomus tumors and suggested hemangiopericytoma (HPC) as properly descriptive name [4]. Two of the described tumors originated in head and neck sites (infraorbital and auricular). In 1949, Stout expanded on his previous work by better delineating the histological details of 25 cases of hemangiopericytoma submitted to him from medical centers around the country. Two of these originated in the head and neck; the first reported case was of nasal HPC, another was in the tongue base [5,6]. Since then, only approximately 300 cases of HPCs have been mentioned in the literature [7]. Over the years, it appeared that this growth pattern was a non-specific one, shared by numerous, unrelated benign and malignant lesions, and that HPC was better considered as a diagnosis of exclusion. Three categories of lesion may now be individualized within the heterogeneous group of HPC like neoplasms. The first category corresponds to those non-hpc neoplasms that occasionally display HPC-like features (e.g. synovial sarcoma). Lesions belonging to the second category show clear evidence of myoid/pericytic differentiation and correspond to true HPCs. They generally show a benign clinical course, and include glomangiopericytoma/myopericytoma, infantile myofibromatosis (previously called infantile HPC), and a subset of sinonasal HPCs. The third category is the solitary fibrous tumor (SFT) lesional group, which includes fibrous-to-cellular SFTs, and related lesions such as giant cell angiofibromas and lipomatous HPCs. In practice, any HPC-like lesion can be allocated to one of these categories, leaving the ill-defined haemangiopericytoma category empty [3]. The behavior of cellular SFT varies both on its clinical presentation and on histological examination. Thereby we may Fig 2: Coronal axial sections showing vascular tumour, plane of origin. have a tumor with aggressive clinical presentation, with metastases and increased mitotic activity on the histopathological examination or we may have a tumor with a relatively benign behavior, which increases only locally, without giving metastases [8]. Cellular SFT is uncommon mesenchymal tumor, accounting for 1% of all blood vessel-related neoplasms and less than 3-5% of all soft tissue sarcomas [9]. Such a tumor can occur in any site throughout the human body, since there are everywhere capillaries and they have pericytes. Enzinger and Smith [10] evaluated 106 solitary fibrous tumors and concluded that the commonest site is lower extremity (35%) followed by pelvis or retroperitoneum (25%), trunk (14%) and upper extremity (10%). It has also been described occurring in the brain and spine, oesophagus, breast and lung. Comparing the few clinical observations, that exist, the 72 RADIOLOGY & IMAGING

73 frequency of occurrence in the head and neck is estimated between 16% and 33% of all cellular SFTs occurring in various localizations [11]. In the head and neck region it has been described in the orbit, nasal cavity, oral cavity, jaw, parotid gland, parapharyngeal space, masticator space, jugular foramen, etc. [12]. Cellular SFT may occur in all age groups, predominantly in the 6th and 7th decades, with no sex predilection. The etiology is unknown, although the presence of cellular SFT has been linked to trauma, prolonged steroid use and hormonal imbalance [13]. Clinical features: Clinically, the cellular SFT usually presents as a painless enlarging mass [2], symptoms being mostly due to pressure on adjacent structures [12]. Various paraneoplastic syndromes have been described in association with cellular SFT, including hypoglycemia, hypophosphatemic osteomalacia and hypertrophic pulmonary osteoarthropathy [14]. focal [3]. Criteria of malignancy for SFT include large tumor size (> 50 mm), disseminated disease at presentation, infiltrative margins, high cellularity, nuclear pleomorphism, areas of tumor necrosis and an increased mitotic index (> 4 mitoses per 10 high-power fields (HPF) [17]. Differential diagnosis: Diagnosis of highly vascularized tumors in the head and neck is challenging, especially because of the difficulty in differentiating cellular SFTs from other tumors that have prominent vascularization: schwannoma, myofibroblastoma, metastasis from spindle-cell carcinoma, lowgrade fibromyxoid sarcoma (especially if myxoid foci are prominent), synovial sarcoma, and malignant peripheral nerve sheath tumor [3]. Angiographic features may help in differentiating cellular SFTs from other hypervascular lesions. Tomography, radiography and angiography are not specific and magnetic resonance imaging reveals a solid mass with isodense contrast in T1 [7]. Treatment and prognosis: Survival is correlated with the grade, size, and margin status [17]. Previous reports have examined the effect of grade on the prognosis of patients with cellular forms of SFTs occurring at different sites throughout the body. Enzinger and Smith [10] had analyzed 106 cases of cellular SFTs. In one of their reports, 16% of patients had lesions in the head and neck region, and overall survival was 70%. The authors defined a lesion as high grade if it demonstrated more than four mitotic figures per 10 high-power fields, or displayed increased cellularity or necrosis. In tumors with more than four mitotic figures per 10 high-power fields, 10-year overall survival was 29%. In contrast, patients whose tumors demonstrated four or fewer mitotic figures per high-power field had a 10- Histopathological features: Cellular forms of SFT resemble what had been called HPC prior to Usually they have a monotonous appearance, even, moderate to high cellularity, little intervening fibrosis, numerous thin-walled stag horn branching vessels, and roundto-oval monomorphic tumor cell nuclei [15,16]. Immunohistochemically, tend to be less frequently positive for CD34 than fibrous SFT; when positive, the staining is usually less strong than in fibrous SFT and often RADIOLOGY & IMAGING Fig 3: Saggital axial sections showing vascular tumour extension. 73

74 Fig 4: Vascular tumour in colour Doppler screening mode. Consent Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal. 74 RADIOLOGY & IMAGING

75 References: 1. Wagner E, Wunderlich CA, Roser W: Das tuberkelähnliche Lymphadenom. (Hrsg) 1870, S Gerner RE, Moore GE, Pickren JW: Hemangiopericytoma. Ann Surg 1975, 179: Gengler C, Guillou L: Solitary fibrous tumour and haemangiopericytoma: evolution of a concept. Histopathology 2006, 48: Stout A, Murray MR: Hemangiopericytomas: vascular tumors arising from Zimmerman s pericytes. Ann Surg 1942, 116: Billings KR, Fu YS, Calcaterra TC, Sercarz JA: Hemangiopericytoma of the head and neck. Am J Otolaryngol 2000, 21: Stout AP: Hemangiopericytoma. A study of twenty five new cases. Cancer 1949, 2: Carvalho JR, Haddad L, Leonhardt FD, Marques Filho MF, Santos R, de O, Cervantes O, Abrahão M: Head and neck hemangiopericytoma in a child: case report. Sao Paolo Med J 2004, 122: Koscienly S, Brauer B, Forster G: Hemangiopericytoma: a rare head and neck tumor. Eur Arch Otorhinolaryngol 2003, 260: Palacios E, Restrepo S, Mastrogiovanni L, Lorusso GD, Rojas R: Sinonasal hemangiopericytomas: clinicopathologic and imaging findings. Ear Nose Throat J 2005, 84: Enzinger FM, Smith BH: Hemangiopericytoma: an analysis of 106 cases. Hum Pathol 1976, 7: Stomeo F, Fois V, Cossu A, Meloni F, Pastore A, Bozzo C: Sinonasal haemangiopericytoma: a case report. Eur Arch Otorhinolaryngol 2004, 261: RADIOLOGY & IMAGING 12. S Digumarthy R, Peri N, Malladi UD, Jinna JMR, Sundaram C: Haemangiopericytoma of the Internal Jugular Vein: an unusual neck mass. Clin Radiol Extra 2003, 58: McMaster MJ, Soule EH, Ivins JC: Hemangiopericytoma: A clinicopathologic study and long-term follow up of 60 patients. v1975, 36: Lorigan JG, David CL, Evans HL, Wllace S: The clinical and radiologic manifestations of hemangiopericytoma. Am J Roentgenol 1989, 153: van Kints MJ, Tjon RTO, Tham A, Klinkhamer PJJM, van den Bosch HCM: Haemangiopericytoma of the breast: mammographic and sonographic findings. Am J Roentgenol 1994, 163: Gold JS, Antonescu CR, Hajdu C, Ferrone CR, Hussain M, Lewis JJ, Brennan MF, Coit DG: Clinicopathologic correlates of solitary fibrous tumor. Cancer 2002, 94: Kraus DH, Dubner S, Harrison LB, Strong EW, Hajdu SI, Kher U, Begg C, Brennan MF: Prognostic factors for recurrence and survival in head and neck soft tissue sarcomas. Cancer 1994, 74: Backwinkel KD, Diddams JA: Hemangiopericytoma: report of a case and comprehensive review of the literature. Cancer 1970, 25: Walike JW, Bailey BJ: Head and neck hemangiopericytoma. Arch Otolaryngol 1971, 93: Chiechi MV, Smirniotopoulos JG, Mena H: Intracranial hemangiopericytomas: MR and CT features. Am J Neuroradiol 1996, 17: Espat NJ, Lewis JJ, Leung D, Woodruff JM, Antonescu CR, Shia J, Brennan MF: Conventional hemangiopericytoma: a modern analysis of outcome. Cancer 2002, 95: Mira JG, Chu FC, Fortner JG: The role of radiotherapy in the management of malignant hemangiopericytoma: report of eleven new cases and review of the literature. Cancer 1977, 39: Heckmayar M, Gatzemeier U, Radenbach D, Liebig S, Fasske E, Magnussen H: Pulmonary metastazing hemangiopericytoma. Am J Clin Oncol 1988, 11: Craven JP, Quigley TM, Bolen JW, Raker EJ: Current management and clinical outcome of hemangiopericytoma. Am J Surg 1992, 163:

76 Case Presentation: Primary synovial osteochondromatosis of the ankle JW Walike MD, BJ Bailey MD Case presentation DESCRIPTION: A 54-year-old man presented with an 18-month history of chronic left ankle pain and swelling. The pain was a dull ache and present throughout the day. On examination, there was swelling of the left ankle, more anteriorly, with palpable loose bodies. There was associated terminal restriction of motion. Radiographs of the left ankle revealed multiple subcentimeter osseous structures in the anterior of the tibiotalar joint. Sagittal T1-weighted MRI showed multiple subcentimeter hypointense structures in the same localisation as determined on the ankle radiographs. Imaging confirmed the diagnosis of primary synovial osteochondromatosis of the left ankle. He was treated by open excision of the osteochondromatous lesions within the joint. Primary synovial osteochondromatosis is an uncommon generally benign disorder characterised by formation of cartilaginous bodies within the synovia of the different joints, tendon sheaths and bursae. Although the aetiology is unknown, there are data suggesting neoplastic origin with chromosome 6 abnormalities. 1. It most commonly involves large joints such as the knee, hip and elbow. Depending on the location, there can be little restriction on the range of motion, which could allow significant growth of the cartilaginous bodies and thus delayed diagnosis of osteochondromatosis. 2. The diagnosis of synovial osteochondromatosis is commonly made following a thorough history, physical examination and radiological examination. Since this condition tends to be progressive but self-limiting, indications for surgery depend on the level of symptomatic presentation in addition to the functional demands of the patient. Patient consent and ethical committee clearance obtained. Conflict of interest: none declared. REFERENCES: 1 Buddingh EP, Krallman P, Neff JR, et al. Chromosome 6 abnormalities are recurrent in synovial chondromatosis. Cancer Genet Cytogenet 2003;140:18Y22. 2 Lue A, Chernev I, Yan K. Extra-articular osteochondromatosis. Am J Phys Med Rehabil 2011;90: RADIOLOGY & IMAGING

77 Case presentation Primary hydatid cyst of brain: RF Browne MD, DJ Tuite MD. ABSTRACT: Brain involvement with hydatid disease occurs in 1 2% of all Echinococcus granulosus infections. Isolated cerebral hydatid disease is a rare manifestation of it. In this report, we analyze two cases of isolated cerebral hydatid cysts and discuss their mode of presentation, radiological features, operative procedure and outcome. In our two cases, radiological features and surgical approaches were different from one another. The literature concerning isolated cerebral hydatid disease is reviewed. Key words: Dowling Orlando technique, Echinococcus, isolated cerebral hydatid cyst CASE REPORT: A 22 year old male presented to us with complaints of headache for last 4 months, vomiting intermittently for 4 days and disorientation for 2 days. On physical examination, he was disoriented with bilateral papilledema and right sided hemiparesis. Computed tomography (CT) scan and magnetic resonance (MR) imaging DISCUSSION: Intracranial hydatid cyst may be classified as primary or secondary. [1] Primary cysts are formed as a result of direct infestation of the larvae in the brain without demonstrable involvement of other organs. Lack of effective immune system in the brain, special architecture of brain tissue, patent ducts arteriosus and patent foramen ovale have been the proposed factors for isolated cerebral hydatid disease. In our two cases, echocardiography revealed no abnormality. Magnetic resonance and CT scans RADIOLOGY & IMAGING of the brain [Figure 1a and b] were suggestive of a large multi cystic lesion in parieto occipital region. Lesion was removed by a large right parieto occipital craniotomy. Due to large size, in toto removal was not possible. Cyst wall was punctured; multiple daughter cysts removed one by one [Figure characteristically show a spherical, well defined, non enhancing cystic lesion without peripheral edema. [2,3] The fluid density is generally equal to that of cerebro spinal fluid on both CT and MR scan. MR spectroscopy studies show pyruvate peaks besides lactate, alanine and acetate.[4] The treatment of hydatid cyst is surgical, and the aim of surgery is to excise the cyst in toto without rupture to prevent recurrence and anaphylactic reaction. Dowling Orlando technique remains the preferred method, in which 1c]. After intra cystic decompression, laminated membrane was removed by irrigating warm saline between cyst wall and brain interface. Pathological examination confirmed it as hydatid cysts. X ray chest and USG of abdomen failed to show any lung or liver lesions. Five years after surgery, he remained well and free of disease. the cyst can be delivered by lowering the head of the operating table and instilling warm saline between the cyst and the surrounding brain parenchyma. This is possible because of minimal adhesions around the cyst wall.[5] Isolated case reports showed complete disappearance of multiple intracranial hydatid cysts with albendazole therapy in a daily dose of 10 mg/kg, taken three times a day for 4 months.[6,7] 77

78 Conclusion: Incidence of primary hydatid cyst of brain is very rare. Patent ductus arteriosus and patent foramen ovale have been the proposed factors. In our cases, larvae might have passed through the capillary References: Fig 1 filter of the liver and lungs, entered into the systemic circulation and reached the brain. Aim should be in toto removal of the cyst. Sometimes because of large size, it is not possible, in that case intracystic decompression followed by removal of cyst wall by gentle traction and saline irrigation between cyst wall brain interfaces is a better option. 1. Nurchi G, Floris F, Montaldo C, Mastio F, Peltz T, Coraddu M. Multiple cerebral hydatid disease: Case report with magnetic resonance imaging study. Neurosurgery 1992;30: Coates R, von Sinner W, Rahm B. MR imaging of an intracerebral hydatid cyst. AJNR Am J Neuroradiol 1990;11: Karak PK, Mittal M, Bhatia S, Mukhopadhyay S, Berry M. Isolated cerebral hydatid cyst with pathognomonic CT sign. Neuroradiology 1992;34: Kohli A, Gupta RK, Poptani H, Roy R. In vivo proton magnetic resonance spectroscopy in a case of intracranial hydatid cyst. Neurology 1995;45: Arana Iniguez R. Echinococcus. Infection of the nervous system. In: Vinken PJ, Bruyn GW, editors. Hand Book of Clinical Neurology, Part III. Amsterdam: Elsevier/ North Holland Biomedical Press; p Singounas EG, Leventis AS, Sakas DE, Hadley DM, Lampadarios DA, Karvounis PC. Successful treatment of intracerebral hydatid cysts with albendazole: Case report and review of the literature. Neurosurgery 1992;31: Todorov T, Vutova K, Petkov D, Balkanski G. Albendazole treatment of multiple cerebral hydatid cysts: Case report. Trans R Soc Trop Med Hyg 1988;82: Axial MR sections showing small multiple daughter cyst within large cyst, confirmed in surgery Fig 2 Coronal MR sections showing multiple daughter cysts seen within. 78 RADIOLOGY & IMAGING

79 Soft tissue myxoid sarcoma of elbow- A rare case report A Kohli MD, RK Gupta MD, H Poptani MD. Case presentation ABSTRACT: We reported on one patient with high-grade soft-tissue sarcomas mimicking traumatic intramuscular hematomas. Patient had an episode of trauma to the extremity, and after initial clinical and imaging evaluations they were considered to have muscular hematomas. The lesions increased in size over time, leading to further evaluations that demonstrated the INTRODUCTION: Sarcomas comprise approximately one percent of malignant tumors and represent a significant diagnostic and therapeutic challenge.14 The incidence of softtissue sarcomas in the United States ranges from 20 to 30 per 1,000,000 persons, approximately 6,000 new cases per year.13 Soft-tissue sarcomas are a heterogeneous group of tumors that arise from tissue of mesenchymal origin and are characterized by infiltrative local Case Report: A healthy 44-year-old female suffered trauma to her left arm, falling on her outstretched hand while working. After an initial evaluation by her local physician she was diagnosed with a muscle strain with a concomitant hematoma. The patient started physical therapy, however there was no improvement of her symptoms and she again consulted the physician RADIOLOGY & IMAGING actual diagnosis. We conducted a retrospective review of the clinical findings, magnetic resonance images, and computed tomography scans to assess characteristics that will help in the differential diagnosis. We conclude that intramuscular hematomas following trauma should be approached with a high degree of clinical suspicion. MRI analysis can be used as an growth. The metastatic spread of sarcomas is mainly hematogenous to the lungs, although lymphatic spread may occur. Soft-tissue sarcomas can occur at any site throughout the body.5 Almost 45 percent of all soft tissue sarcomas are found in the extremities, especially in the lower limb. Patients usually present with a complaint of a lump or growth, with or without pain. However, there are some instances in which the patient will a week later. An MRI was then ordered which showed a well-circumscribed mass not attached to the humerus along the lateral border of the left biceps brachii muscle, measuring 14.5 x 6.5 x 5 centimeters, with an intermediate signal in T1, and a high signal in T2. The radiologist and the attending physician interpreted the MRI as a muscular hematoma. important diagnostic tool, but the results must be seen in the context of the clinical history. MRI is not sensitive or specific enough to rule out malignancy. The diagnosis of a high grade sarcoma must be considered in these patients and any doubt should be resolved with a biopsy. present after moderate trauma to the extremity. These cases are very challenging since the injury symptoms and imaging studies could mask the underlying tumor. We present the cases of three patients with high-grade sarcomas who initially suffered moderate traumas to their extremities and were initially diagnosed with intramuscular hematomas by clinical and imaging studies. Conservative care was ordered with continued physical therapy. Six months after the traumatic episode she had no improvement, and the patient was referred to an orthopedic surgeon in another institution for evaluation. A new MRI was interpreted as being compatible with a soft-tissue sarcoma, and the patient was referred for treatment to our institution. 79

80 When the patient arrived, she presented with mild pain in her left upper arm, with numbness in the hand when outstretched. The physical examination showed a 15 centimeter, firm, non-tender soft-tissue mass in the left upper arm along the biceps muscle that adhered to the subcutaneous tissue. The motor and sensory functions of the left upper extremity were normal. We performed a wide excisional biopsy and found a wellcircumscribed soft-tissue mass located in the left biceps brachii muscle. The pathology sections showed a highgrade sarcoma with a fine vascular background. After the surgical resection, the patient recovered well and received radiation therapy with no relapses or documented metastases at the time this report was made DISCUSSION : Imaging provides the clinician with crucial information in the diagnosis, staging, treatment planning, treatment evaluation, and post-treatment assessment of patients with soft-tissue sarcoma. Thanks to high-contrast tissue resolution and multiplanar imaging capability, MRI remains the gold standard for evaluation of most soft-tissues lesions. However, the sensitivity for diagnosis and grading remains controversial in the literature. MRI is not able to predict malignancy, and the findings commonly associated with malignant lesions frequently overlap with those seen in benign tumors.4 Furthermore, a significant percentage of malignant lesions may appear deceptively benign with the currently used criteria.9,10 MRI also performs poorly in the histological classification of softtissue tumors.10 This is because MRI images provide only indirect information about tumor histology by showing signal intensities related to some physicochemical properties of the tumor components, and consequently reflect gross morphology of the lesion rather than underlying histology. Finally, the time-dependent changes of the tumors (as a consequence of intratumor necrosis and/or bleeding), makes the differentiation process even more difficult. Differentiating between malignant and benign softtissue lesions has proven to be a difficult task even with the advantage of MRI. Soft-tissue tumors grow in a centrifugal manner until resistance is met. The barriers in soft tissues consist of major fibrous septa and the origins and insertions of muscles. Growth tends to occur in the plane of least resistance, which in soft-tissue tumors occurs in a longitudinal fashion (i.e., in the compartment of origin). The host responds to tumor growth by creating a reactive fibrovascular tissue that forms a limiting capsule in benign lesions. Aggressive lesions, however, compress the host reactive tissue into a pseudocapsule containing finger-like or nodular tumoral foci called satellite lesions. In highly aggressive lesions, tumoral foci (skip metastases) are found beyond the reactive zone within the compartment of origin. As we mentioned, MRI usefulness as a valid predictor of malignancy in soft-tissue lesions is debatable. However there are some individual parameters for predicting malignancy in MRI images: 1) Intensity and homogeneity of the MR signal on different pulse sequences; 2) High-signal intensity on T2-weighted images; and 3) Homogeneity on T1-weighted images. These are sensitive parameters but present with an unacceptably low specificity. Indeed, high-grade malignant soft-tissue tumors may show low-to-intermediate signal intensity on T2-weighted images because of an increased nucleocytoplasmic index and an altered cellular and interstitial components proportion, both resulting in a decrease of intra- and extra-cellular water.1,2 Hermann et al. reported that changes in homogeneity (from homogeneous on T1- weighted images to heterogeneous on T2-weighted images) and the presence of low-signal intratumoral septations have a sensitivity of 72 and 80 percent and a specificity of 87 and 91 percent, respectively, in predicting malignancy. Other signs related to malignancy include the presence of tumor necrosis, bone or neurovascular involvement, mean diameter of more than 66 millimeters, and irregular or partially irregular margins.4 Finally, no predominant enhancement pattern is characteristic of benign or malignant lesions. Unfortunately, as deduced from the previous data, none of these parameters is reliable enough to precisely assess the benign or malignant condition of a lesion on MRI images. MRI images of acute hematomas show low-to-intermediate signal intensity on T1, and low signal on T2. These same findings are seen in desmoids and other fibromatoses, pigmented villonodular synovitis, fibrolipohamartomas, giant cell tumors of the tendon sheath, xanthomas, high-flow arteriove- 80 RADIOLOGY & IMAGING

81 nous malformations, mineralized masses, scar tissue, amyloidosis, granuloma annulare and highgrade sarcomas. Intratumoral hemorrhage is a rare finding that can be observed in benign and malignant lesions, and is difficult to differentiate from non-tumoral soft-tissue hematoma. Moulton et al.11 evaluated 23 benign and 5 malignant tumors with hemorrhage in a total of 225 masses. Hemorrhage was diagnosed on the basis of high signal on T1-weighted images, coupled with low or high signal on T2-weighted images, provided the tissue was not isointense to fat in all sequences. A lowsignal hemosiderin rim was interpreted as evidence of prior hemorrhage. In Table 1 we show the MRI image characteristics of some of the more common soft-tissue lesions and hematomas. There are three reports in the literature of high-grade sarcomas mimicking hematomas in the extremities. Ogose et al.12 reported an extra-skeletal Ewing sarcoma mimicking a traumatic hematoma in a 16-year-old boy with a history of recurrent hematoma in the thigh. RADIOLOGY & IMAGING 81

82 These lesions were characterized by rapid growth. Interestingly, the cytology of percutaneous aspiration was negative for malignancy in five of the six patients, and the final diagnosis was only made after an open biopsy several weeks later. Finally, Engel et al.,6 reported on a young man who received trauma to his thigh that was initially diagnosed as an organizing Conclusion: We conclude that intramuscular hematomas following trauma should be approached with a high degree of clinical suspicion. MRI analysis can be used as an importhematoma of the adductor compartment. At surgery, evidence of a tumor was found that was histologically identified as a synovial sarcoma. In their study8, Imaizumi et al. retrospectively reviewed the history and imaging studies and concluded that MRI was a reliable diagnostic tool for the differentiation between hematoma and ant diagnostic tool, but the results must be seen in the context of the clinical history. MRI is not sensitive or specific enough to rule sarcoma. However, as presented in this report, the MRI images can be very similar in both pathologies, and high-grade soft-tissue sarcoma cases presenting after some degree of trauma could easily be mistaken initially as hematomas related to that recent injury. out malignancy. The diagnosis of a myxoid sarcoma made with a biopsy. BIBLIOGRAPHY: 1. Berquist TH, Ehman RL, King BF, Hodgman CG, Ilstrup DM. Value of MR imaging in differentiating benign from malignant soft-tissue masses: study of 95 lesions. AJR Am J Roentgenol 1990; 155(6): De Schepper A, Grading and characterization of soft tissue tumors. Imaging of soft tissue tumors, ed. De Schepper A, (1997), Berlin Heidelberg New York: Springer De Schepper A, De Beuckeleer L. Imaging of soft tissue tumors in the pediatric patient. Semin Musculoskeletal Radiol 1999; 3: De Schepper AM, De Beuckeleer L, Vandevenne J, Somville J. Magnetic resonance imaging of soft tissue tumors. Eur. Radiol 2000; 10: Eilber FC, Rosen G, Nelson SD, Selch M, Dorey F, Eckardt J, Eilber FR. High-grade extremity soft tissue sarcomas: factors predictive of local. Annals of surgery 2003; 237(2): p Engel C, Kelm J, Olinger A. Blunt trauma in soccer. The initial manifestation of synovial sarcoma. Zentralbl Chir. 2001; 126(1): Hermann G, Abdelwahab I, Miller T, Klein M, Lewis M. Tumour and tumour-like conditions of the soft tissue: magnetic resonance imaging features differentiating benign from malignant masses. Br J Radiol 1992; 65: Imaizumi S, Morita T, Ogose A, Hotta T, Kobayashi H, Ito T, Hirata Y. Soft tissue sarcoma mimicking chronic hematoma: value of magnetic resonance imaging in differential diagnosis. J Orthop Sci. 2002; 7(1): Kransdorf M. Benign soft tissue tumors in a large referral population: distribution of specific diagnoses by age, sex and location. Am J Roentgenol 1995; 164: Kransdorf M. Malignant soft tissue tumors in a large referral population distribution of specific diagnoses by age, sex and location. Am J Roentgenol, 1995; 164: Moulton JS, Blebea JS, Dunco DM, Braley SE, Bisset GS III, Emery KH. MR imaging of soft-tissue masses: diagnostic efficacy and value of distinguishing between benign and malignant lesions. AJR Am J Roentgenol 1995;164(5): Ogose A, Hotta T, Yamamura S, Shioya Y, Yazawa T. Extraskeletal Ewing s sarcoma mimicking traumatic hematoma. Arch Orthop Trauma Surg; 118(3): O Sullivan B, Pisters PW. Staging and prognostic factor evaluation in soft tissue sarcoma. Surg Oncol Clin N Am 2003; 12(2): Rougraff B. The diagnosis and management of soft tissue sarcomas of the extremities in the adult. Current Problems in Cancer. 1999;23: Weitz J, Antonescu CR, Brennan M. Localized extremity soft tissue sarcoma: improved knowledge with unchanged survival over time. J Clin Oncol, 2003; 21 (14): p RADIOLOGY & IMAGING

83 Fig 1: Subcutaneous sarcoma in T1 saggital sequence Fig 2 & 3: Subcutaneous sarcoma in T1 axial sequence Fig 4: Subcutaneous sarcoma in Saggital STIR sequence with minimal muscle invasion. RADIOLOGY & IMAGING 83

84 A complex fistula-in-ano presenting as a soft tissue tumor De Schepper AM, De Beuckeleer Case presentation Abstract: Anorectal abscess and fistula are quite commonly encountered diseases. Both of these are the acute and chronic manifestations of the same entity. While abscess are thought to begin as an infection in the anal glands, their spreading into adjacent spaces results in a fistula formation. At many times this spread occurs in a complex pattern which is difficult to map and treat. This article describes a complex perianal fistula that presented as a painless benign lump in the upper outer quadrant of the right buttock. The lump initially thought to be a soft tissue swelling was later diagnosed to be a chronic abscess cavity extending medially toward the anal canal in the form of a complex fistulous tract. Complex perianal fistulas are difficult to treat and are prone to recurrences. Correct diagnosis and characterization of the fistula is essential to optimize the reatment. Clinical examination alone may not give a correct picture of the actual disease, thereby requiring radiological investigations like MRI. Although rare, sometimes common clinical conditions like fistula-in-ano may also present in complex manner. It is important to establish the diagnosis firmly and map the fistula properly before going in for surgery. Complexity of fistulas and improper mapping often leads to recurrences and other complications like incontinence. Keywords: Fistula in ano, Fistula, Soft tissue mass, Antibioma, Abscess, Perianal 84 RADIOLOGY & IMAGING

85 INTRODUCTION: The accurate diagnosis and mapping of perianal fistulas has long been a challenge to surgeons worldwide. Most perianal abscesses originate from an infected anal gland. Obstruction of these glands leads to stasis, bacterial overgrowth, and ultimately abscesses that are located in the intersphincteric groove [1]. These abscesses have several routes of egress, the most common of which are downward extension to the anoderm (perianal abscess) or across the external sphincter into the ischiorectal fossa. Less common routes of spread are to the supralevator space or in the submucosal plane. When the abscess is drained, either surgically or spontaneously, persistence of the septic foci and epithelialization of the draining tract may occur and lead to a chronic fistula-in-ano. About 60% of the abscesses do result into such a fistula formation [2]. In the presented case, there was an extra-sphincteric fistulous tract which extended superiorly, traversed the right ishiorectal fossa, breached the levator-ani plate and presented as a large and chronic abscess in the subcutaneous region of the right buttock. A 26 years old man presented to our surgical clinic with the complaints of a painless lump in the right buttock region for two and a half years. The swelling was gradually increasing in size. There was no other significant history that could be linked to the swelling. History of constipation accompanied with use of powdered laxatives was present. The lump on examination was a non tender freely mobile well defined lump lying superficial in the subcutaneous plane. An initial diagnosis of soft tissue benign tumor was made. As a part of the RADIOLOGY & IMAGING initial work up all routine blood test along with chest X-ray were done and found to be normal. A fine needle aspiration from the swelling revealed hemorrhagic fluid, smear from which showed inflammatory cells comprising chiefly of polymorphs and a few macrophages. The ultrasonography of the lump also revealed an inflammatory lesion. In view of a non conclusive diagnosis, a decision to get an MRI study was taken. The MRI study revealed the true nature of the swelling to be an abscess cavity associated to a Grade V perianal fistula via a 7 cm fistulous tract with internal ramifications. The fistulous tract in its perianal course was seen on the right side in the extrasphincteric region extending superiorly, traversing the right ischiorectal fossa with a likely breech of the right levator ani plate. It seemed to terminate medially with no obvious communication to the rectum. The nature of disease, procedure to be performed and prognosis were discussed with the patient and family. After bowel preparation, the patient was taken to the operation room. Under general anesthesia, the patient was placed in a jack-knife position. An incision was given over the lump and a thick walled abscess cavity was discovered (Fig. 3). The cavity was excised en mass. The communicating tract was identified as a thick tract going medially. The fistula tract was laid open to the level of the levator ani (Fig. 4). At this level, digital examination of the tract was done and no obvious communication to the rectum could be detected. Partial excision and curettage of the tract was done. The edges of the remnant tract were marsupialized to the subcutaneous tissue to prevent it from closing down. The wound was left open and the tract and wound were packed. The post operative period was largely uneventful and the patient was discharged satisfactorily on the first post operative day. He was advised regular dressings in the coming period. A histo-pathological examination of the specimen obtained showed features consistent with sinus tract with chronic inflammation. In the follow up, a complete resolution of the fistulous tract was seen. The recovery of the patient was satisfactory however a final verdict can only be placed after a long term follow up. DISCUSSION: A fistula-in-ano represents the chronic phase of ongoing perianal infection. It is a granulating tract between the anorectum and the perianal region or perineum. A typical fistula usually consists of a tract with a primary (internal) opening and a secondary (external) opening. However sometimes the tract may become obliterated and the remnant may appear to be a sinus. Therefore, perianal sinus should be considered as a form of perianal fistula [3]. In the presented case, the pelvic MRI of the patient delineated an extrasphincteric type of fistula with no evidence of communication to the rectum. It seems likely that the internal opening in the rectum was obliterated over time. The remnant tract continued to drain causing the fistula to traverse an unusual course through the levator ani and into the subcutaneous space. The result was a chronic abscess cavity in the right hip. There have been very few case reports where a fistula in ano has 85

86 traversed an unusual course and caused a diagnostic dilemma. For instance a fistula in ano involving and causing septic arthritis of hip has been reported [4]. It is seen that more commonly the challenge faced with a fistula-in-ano is not with the primary diagnosis but with the mapping of the fistula. In the case presented, initial diagnosis of a fistula could not be made till the time a MRI was conducted. The initial impression was of soft tissue swelling. Neither an FNAC nor an ultrasound could pick the diagnosis and hence a MRI of the pelvis was taken up. Several studies have shown MRI to be highly useful for tract mapping as well as for predicting the patient outcome, formulating management plan and monitoring therapy [5,6]. MRI grading classification commonly used is: 0, normal appearance; 1, simple linear intersphincteric fistula; 2, intersphincteric fistula with intersphincteric abscess or secondary fistulous track; 3, trans-sphincteric fistula; 4, trans-sphincteric fistula with abscess or secondary track within the ischioanal or ischiorectal fossa; 5, upralevator and translevator disease. This MRI grading has been shown to correlate with the outcome: grades 1 and 2 are associated with favorable outcome, while grades 3 5 are associated with less favorable outcome leading to recurrences needing reoperations [7,8]. With the knowledge about the tract being a grade V complicated tact, only a partial excision with marsupialization was performed. The concern was to prevent the loss of anal continence. Flatus incontinence may be a minor complication for the surgeon but it could be very embarrassing for the patient [9]. During the post operative period obliteration of the tract without any loss of sphincter function was seen. Fig 1: Complex fistula in posterior soft tissue presenting as mass Fig 2 & 3: xial MR sequences ( STIR & T2 W) showing complex fistula communication with external sphincter. 86 RADIOLOGY & IMAGING

87 CONCLUSION: Perianal pathologies may appear simple but are often misleading. One must always be vigilant for a more complex and rare diagnosis. MRI is a very useful modality in making a diagnosis and predicting the outcome. When dealing with a fistula-in-ano, proper assessment and mapping of the tract is very important before going in for a definitive surgery. CONFLICT OF INTERST: None. ETHICAL APPROVAL: Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request. 1.Parks A.G. Pathogenesis and treatment of fistula-in-ano. Br Med J. 1961;1: [PubMed] 2.2. Robinson A.M., Jr., De- Nobile J.W. Anorectal abscess and fistula-in-ano. J Natl Med Assoc. 1988;80(11): [PubMed] 3.3. Kim J.W., Kwon S.W., Son S.W., Ahn D.H., Lee K.P. Comparative review of perianal sinus and fistula in ano. J Korean Soc Coloproctol. 2000;16: Chen C.-W., Wu C.-C., Hsiao C.-W., Wang S.-J., Jao S.-W. Septic arthritis of hip joint secondary to an anal fistula. J Med Sci. 2008;28(3): Spencer J.A., Ward J., Beckingham I.J., Adams C., Ambrose N.S. Dynamic contrast-enhanced MR imaging of perianal fistulas. AJR Am J Roentgenol. 1996;167(3): [PubMed] 6.6. Spencer J.A., Chapple K., Wilson D., Ward J., Windsor A.C., Ambrose N.S. Outcome after surgery for perianal fistula: predictive value of MR imaging. AJR Am J Roentgenol. 1998;171(2): [PubMed] 7.7. Morris J., Spencer J.A., Ambrose N.S. MR imaging classification of perianal fistulas and its implications for patient management. Radiographics. 2000;20(3): [PubMed] 8.8. Torkzad M.R., Karlbom U. MRI for assessment of anal fistula. Insights Imag. 2010;1(May (2)): [PMC free article] [PubMed] 9.9. Garcia-Aguilar J., Belmonte C., Wong W.D., Goldberg S.M., Madoff R.D. Anal fistula surgery. Factors associated with recurrence and incontinence. Dis Colon Rectum. 1996;39: [PubMed] References: RADIOLOGY & IMAGING 87

88 A Rare case report of emphysematous cholecystitis with perforation without hemo/pneumoperitoneum. T Todorov MD, K Vutova MD, D Petkov MD Case presentation Abstract: A 65-year-old man with a history of diabetes mellitus and hypertension was admitted because of right upper quadrant pain, nausea and palpable right quadrant mass. On admission the patient was febrile (38.8 C) with a total bilirubin level of 1.99 mg/dl (direct 0.59 mg/dl); SGOT 1.26 mg/dl; Na 135 mmol/l and K 2.9 mmol/l. The white blood count was 15200/μl with Background: 92.2% neutrophiles. Axial sections of single slice CT imaging (section thickness 10 mm), revealed emphysematous cholecystitis with thickening of gallbladder wall and wall enhancement after iv contrast enhancement, as well as, dilatation of the gallbladder with multiple gallstones precipitate and intraluminal air. The patient underwent subtotal cholecystectomy and a cholecystostomy was placed. The culture of the bile showed positivity to toxin A of Clostridium Difficile and to Escherichia Coli. The postoperative course of the patient was uneventful. Key words- Emphysematous cholecysitis ( EC), Perforation. Emphysematous cholecystitis (E.C) is an uncommon variant of acute cholecystitis in which the causative organisms are gas-forming bacteria. E.C has been defined clinically by the imaging demonstration of air in the gallbladder lumen; in the wall, or in the tissues adjacent to the wall of the gallbladder; and elsewhere in the biliary ducts in the absence of an abnormal communication with the gastrointestinal tract [1]. E.C is pathophysiologically different from acute or chronic cholecystitis. Obstruction of the gallbladder neck secondary to cholelithiasis induces acute and chronic cholecystitis. However, E.C mostly results from thrombosis or occlusion of the cystic artery with ischemic necrosis of the gallbladder wall. The aim of the present article is to present a case of EC and to attempt to elucidate the clinical entity and management of emphysematous cholecystitis Case Report: A 65-year-old man with a history of diabetes mellitus and hypertension was admitted because of right upper quadrant pain, nausea and palpable right quadrant mass. On admission the patient was febrile (38.8 C) with a total bilirubin level of 1.99 mg/dl (direct 0.59 mg/dl); SGOT 1.26 mg/dl; Na 135 mmol/l and K 2.9 mmol/l. The white blood count was 15200/μl with 92.2% neutrophiles. Axial sections of single slice CT imaging (section thickness 10 mm), revealed emphysematous cholecystitis with thickening of gallbladder wall and wall enhancement after iv contrast enhancement, as well as, dilatation of the gallbladder with multiple gallstones precipitate and intraluminal air (Figure (Figure1).1). The patient underwent 88 RADIOLOGY & IMAGING

89 subtotal cholecystectomy [2] and a cholecystostomy was placed. The culture of the bile showed positivity to toxin A of Clostridium Difficile and to Escherichia Coli. The postoperative course of the patient was uneventful. Discussion: RADIOLOGY & IMAGING Emphysematous cholecystitis (EC) is a virulent form of acute cholecystitis accompanied by gas formation [1]. E.C frequently affects elderly men, and it is associated with diabetes mellitus. The risk of gangrene and perforation of the gallbladder is relatively high for patients with E.C, and the mortality rate is 15% [1]. The presenting symptoms of EC are usually very vague and initially indistinguishable from those of uncomplicated acute cholecystitis, frequently causing a diagnostic dilemma [3]. The clinical presentation may adopt different forms, from minimal pain to septic shock [4]. The succeeding symptoms and signs depend on the evolution of the disease [5]. The diagnosis of E.C is based on the demonstration of varying amounts of gas in the gallbladder lumen and wall, and occasionally in the bile ducts [6]. Intraluminal gas is depicted as one or several round bubbles or a pear-shaped lucency in the right upper quadrant on a supine film or on an air-fluid level within the gallbladder on an erect or decubitus radiograph [7]. Computed tomography is the most sensitive modality for the detection of the intraluminal or intramural gallbladder gas [8], and it can also demonstrate local complications, such as pericholecystic inflammatory changes, abscess formation, or perforation [9]. Prompt diagnosis is essential, as early intervention can minimize the serious morbidity and mortality rates associated with emphysematous cholecystitis. CT might be the best technique for diagnosing EC because it shows the exact location of air, whether in the gallbladder wall, in the gallbladder lumen, or throughout the bile duct, but it is irrational to perform CT for all patients with vague abdominal symptoms.ultrasonography (US) is now the first diagnostic tool for observing the gallbladder. Thus, in a clinical setting, US can be used to diagnose EC early and correctly and when the examination is positive it should be followed by CT. US findings of EC are thought to depend on the amount and location of gas. The treatment proposed by most authors is cholecystectomy, either conventional or laparoscopic. As an alternative technique percutaneous cholecystectomy may be used, if the patient s situation is not good enough for surgical treatment.however, occasional cases of total recovery solely with conservative therapy (intravenous fluids, antibiotics and analgesia) have been reported. All authors agree that a rapid clinical deterioration, especially with the presence of a palpable mass in the right upper quadrant, warrants immediate intervention. The pathogens responsible for the gas formed in EC are usually anaerobes like Clostridium, or other microorganisms like E. Coli, P. Vulgaris, A. Aerogenes, Staphylococcus, Streptococcus, Klebsiella and B. Fragilis that under special conditions, are able to produce gas. Both Clostridium and E. Coli are common bacteria present in the gastrointestinal tract, especially in the colon and small bowel, or even in the duodenum when local aggressive factors take place (peptic ulcer, digestive surgery e.t.c.). Thereafter, they can migrate from the duodenum to the biliary tract, and it is common to find these microorganisms in bile cultures when there is any pathology in the region,although gas production is rare. It may be possible that these bacteria acquire pathogenicity if they proliferate in a previously altered gallbladder. Nevertheless, anaerobic bacteria are the most frequent gas forming microorganisms, and they proliferate only in areas with a poor irrigation, and consequently, with a low oxygen saturation. Conclusion: In conclusion, emphysematous cholecystitis is a rare form of cholecystitis that carries a high mortality. Vascular occlusion can be very important in the development of the disease. Ultrasonography has to be performed to all patients, despite the fact that CT is the most accurate imaging technique. Antibiotic therapy should begin quickly and include coverage of common pathogens, particularly Clostridia. Surgical intervention should take place as early as possible with consideration of the patient s potential for deterioration. 89

90 REFERENCES: 1.Mentzer RM, Golden GT, Chandler JG, Horsley JS. A comparative appraisal of emphysematous cholecystitis. Am J Surg. 1975;129: Katsohis C, Prousalidis J, Tzardinoglou E, Michalopoulos A, Fahantidis E, Apostolidis S, ALetras H. Subtotal Cholecystectomy. HPB Surgery. 1996;9: Sherlock S, Dooley J. Gallstones and inflammatory gallbladder diseases. In: Sherlock S, Dooley J, editor. Diseases of the liver and biliary system. London: Blackwell Scientific; pp Tellez LG, Rodriguez-Montes JA, de Liz SF, Martin LG. Acute emphysematous cholecystitis. Report of twenty cases Hepatogastroenterology. 1999;46: Watson DI, Isaacs J, Williams RS. Emphysematous cholecystitis can cause pneumoperitoneum. Aust N Z J Surg. 1994;64: Harley WD, Kirkpatrick RH, Furrucci JT. Gas in the bile ducts (pneumobilia) in emphysematous cholecystitis. AJR Am J Roentgenol. 1978;131: Rosoff L, Meyers H. Acute emphysematous cholecystitis: an analysis of ten cases. Am J Surg. 1966;111: McMillin K. Computed tomography of emphysematous cholecystitis. J Comput Assist Tomogr. 1985;9: Terrier F, Becker CD, Stoller C, Triller JK. Computed tomography in complicated cholecystitis. J Comput Assist Tomogr. 1984;8: Holgersen LO, White JJ, Jr, West JP. Emphysematous cholecystitis: a report of five cases. Surgery. 1971;69: Fig 1: GB calculus with sludge and air in the gall bladder wall. Fig 2: Gall bladder wall is thickened with multiple air pockets seen in wall. Fig 3: Gall bladder within gas forming calculus showing partial Mercedes sign. Fig 4: Coronal reconstruction showing wall emphysema with multiple air pockets. 90 RADIOLOGY & IMAGING

91 Unusual case of dermoid cyst with right side pyosalpinx. G Girish MD, WK Choo MD, SK Morcos MD INTRODUCTION: Dermoid cyst, or mature cystic teratoma, is the most common type of ovarian germ cell tumor. It is frequently multi-cystic, and contains sebaceous fluid as well as hair, teeth, bone, and skin. Dermoid cyst is a relatively common ovarian tumor that is an infrequent cause of abdominal and flank pain. CASE REPORT: A 36-year-old nulliparous woman presented for right lower abdominal pain that began suddenly 24 h prior. It was severe, colicky pain with radiation to her right flank. She denied anorexia, fever, dysuria, hesitancy, frequency, vaginal bleeding or discharge, or change in bowel habits. Her last normal menstrual period was 1 month prior, and she was on depo-contraceptives. She was sexually active and monogamous. Her examination was significant for severe right lower quadrant abdominal tenderness with voluntary guarding, without rebound tenderness. She demonstrated right costovertebral angle tenderness. The pelvic and rectal examinations were normal. Urinalysis demonstrated moderate blood, ketones 80 mg/dl, and a negative beta human chorionic gonadatropin. White blood cell count was 8400 cells per cubic ml, with 85% neutrophils. Ultrasound was done as shown in figure ( 1 &2) DISCUSSION: Case presentation Dermoid cyst is a relatively common ovarian tumor that is an infrequent cause of abdominal and flank pain. Pain when it does occur, is from mass effect and ovarian torsion. These tumors have a classic radiographic and ultrasonographic appearance. Dermoid cyst, or mature cystic teratoma, is the most common type of ovarian germ cell tumor, comprising up to 30% of all masses (1). They are bilateral in 10 13% of cases (2). The incidence of malignant elements in a teratoma is low (approximately 1 2%) (3). Gonadal dermoid cysts occur mostly during the reproductive years, between the ages of 20 and 40 years (4). They are frequently multi-cystic and contain sebaceous fluid as well RADIOLOGY & IMAGING as hair, teeth, bone, and skin. Typically, these tumors contain mature tissues of ectodermal (skin, brain), mesodermal (muscle, fat), and endodermal (mucinous or ciliated epithelium) origin (5). They have a characteristic CT scan appearance with fat/fluid level attenuation and calcification or ossification, as demonstrated in Figure 1 (6). The classic sonographic appearance is of a hyperechoic mass known as a dermoid plug or Rokitansky protuberance, as shown in Figure 2 (7). The Rokitansky protuberance is composed of the thickened area of ectodermal tissue from which hair and teeth arise. Pain is often related to the size of the mass, and ovarian torsion is common. Mature cystic teratomas grow slowly at an average rate of 1.8 mm each year, prompting some investigators to advocate non-surgical management of smaller (6-cm) tumors (8). In this case, our patient had pyosalpinx on laparotomy. Her pain was likely related not to the dermoid cyst but rather to the pyosalpinx rupture complication in peritoneal cavity. Upon gross dissection surgery, the dermoid demonstrated a classic appearance of a mature cystic teratoma, demonstrating endodermal, mesodermal, and ectodermal tissues. The patient underwent right salpingo-oophorectomy followed by an uncomplicated post-operative course and eventually pyoslapinx also drained. 91

92 Conclusion: Mature cystic teratoma is one of the commonest benign cystic lesions in ovary in reproductive age group. Dermoid association with pyosalpinx on the ipsilateral or contralateral side is very rare. Literature reported multiple dermoid cyst but association with pyosalpinx rare in literature. REFERENCES: 1. Ayhan A, Bukulmez O, Genc C, Karamursel BS, Ayhan A. Mature cystic teratomas of the ovary: case series from one institution over 34 years. Eur J Obstet Gynecol Reprod Biol 2000;88: Comerci JT Jr, Licciardi F, Bergh PA, Gregori C, Breen JL. Mature cystic teratoma: a clinicopathologic evaluation of 517 cases and review of the literature. Obstet Gynecol 1994; 84 : Einarsson JI, Edwards CL, Zurawin RK. Immature ovarian teratoma in an adolescent: a case report and review of the literature. J Pediatr Adolesc Gynecol 2004;17: Scully RE, Young RH, Clement PB. Tumors of the ovary, maldeveloped gonads,fallopian tube and broad ligament. Atlas pathology. Thirdseries,fascicle23.Washington,DC:ArmedForces Institute of Pathology; Outwater EK, Siegelman ES, Hunt JL. Ovarian teratomas: tumor types and imaging characteristics. Radiographics 2001;21: Garant M, Reinhold C. Dermoid cyst of the ovary: computed tomography diagnosis of an unusual case. Can Assoc Radiol J 1996; 47: Exacoustos C, Romanini ME, Rinaldo D, et al. Preoperative sonographic features of borderline ovarian tumors. Ultrasound Obstet Gynecol 2005;25: Caspi B, Appelman Z, Rabinerson D, Zalel Y, Tulandi T, Shoham Z. The growth pattern of ovarian dermoid cysts: a prospective study in premenopausal and postmenopausal women. Fertil Steril 1997; 68: Fig 1: USG TAS, showing fat fluid level characteristics of dermoid. Fig 2 & 3: showing Pyosalpinx associated with free fluid and dermoid cyst. 92 RADIOLOGY & IMAGING

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