Functional disorders of the ano-rectal compartment - the diagnostic role of dynamic MRI

Transcription

1 Functional disorders of the ano-rectal compartment - the diagnostic role of dynamic MRI Award: Magna Cum Laude Poster No.: C-2490 Congress: ECR 2017 Type: Educational Exhibit Authors: A. P. Caetano, D. Sofia, E. Alves; Lisbon/PT Keywords: Pelvis, Gastrointestinal tract, MR, Imaging sequences, Pelvic floor dysfunction DOI: /ecr2017/C-2490 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 59

2 Learning objectives Demonstrate the great contrast resolution of MRI in direct visualization of anatomic pelvic structures as well the functional assessment of the pelvic floor Describe a number of reference lines and measurement points used to diagnose and grade pelvic floor disorders Document the MRI appearance of disorders associated with ano-rectal dysfunction Evaluate the role of magnetic resonance (MRI) in identification of diseases affecting the ano-rectal evacuation mechanism Every MRI image shown in this presentation belongs to cases from our institution. Since we did not experience patients without some form of ano-rectal pathology, the MRI images that represent "normal anatomy/function" were carefully selected as those that were closest to "true" normal findings. Page 2 of 59

3 Background Introduction Pelvic floor disorders represents a common health problem Women are more affected Advanced age, multiparty, obesity, smoke, previous pelvic surgery, constipation, genetic factors, heavy physical exertion contributes to this problem Symptoms are variable and nonspecific Clinical evaluation of these disorders is insufficient Radiologic evaluation should be preceded by: Clinical history - symptom duration, severity Physical examination Clinical background - obstetric trauma, surgeries, inflammation, infections, Inflamatory Bowel Disease, fistulas, others Colonoscopy/rectosygmoidoscopy Functional tests Others It is always imperative to exclude an organic cause, especially involving the colon and ano-rectal compartment MRI - advantages Doesn't use ionizing radiation - no known adverse biologic effects High contrast resolution (High spatial and temporal resolution) Multiplanar imaging Not limited by structure interposal Doesn't require retrograde opacification of the bladder Doesn't require fasting and intestinal preparation Less operator dependent Higher patient acceptance Allows for direct and integrated study of the pelvic compartments Allows for a broader morphologic and dynamic study of the pelvic floor and the respective support system MRI - limitations Page 3 of 59

4 Less accessibility Slower examination method Claustrophobia Pacemaker Paramagnetic device interference Steep Learning curve When to perform MRI defecography? MRI defecography should be indicated in cases where the patient complaints or another exam provides suggestion of: Constipation Incontinence Defecatory dysfunction Rectal or anal pain Digitation Rectocele, enterocele, cistocele Invagination, prolapse In summary, MRI defecography allows for pelvic floor anatomy and functional evaluation, as well as their respective abnormalities, making a precise diagnosis and provides valuable information on treatment planning. How to perform MRI defecography? The examination requires the use of a body phased array coil and it is performed at our institution in a 1,5 Tesla equipment, in a closed MRI system. There is no need for previous preparation (enema, IV contrast, fasting). It is necessary to explain the process and have the patient sign an informed consent prior to examination. It is essential to explain the procedure to the patient, and to have access to clinical information The following procedures are employed: Opacification of vagina and rectum with ultrasound Gel Contrast introduction is made with a 50cc syringe and a rectal catheter The amount of contrast introduced in the rectum varies between 150 and 250cc (depends on the patient tolerance) Moderately filled bladder Page 4 of 59

5 Patient stays in supine position Use of a disposable diaper is recommended Fig. 45: MRI defecography material - gloves, diaper, ultrasound gel, syringe, probe. Summary of the sequences performed according to our most recent protocol may be separate into anatomical and functional evaluation, and are as follows: Anatomical evaluation - axial, coronal and sagittal T2WI high-resolution images at rest for: Page 5 of 59

6 pelvic support elements (muscles, ligaments, fascias, bones) Sphincteric components organs (uretra, uterus, cervix, vagina, bladder, anal canal and rectum, in women) Functional evaluation - conventional sagital plans T2 Fast spin echo and sagital T2 Cine RM aquisitions: Resting Voluntary contraction of the perineum - valsalva and squeezing maneuvers Defecation (and maximum defecatory effort) Post defecation resting Every study is made in the presence of the radiologist, who directs the exam and evaluates the images Sequence Slice orientation Matrix Slice thickness T1 TSE HR Transversal mm T2 TSE HR Coronal mm T2 TSE HR Transversal mm T2 TSE HR Sagital 384 2,8 mm T2 TRUFI - resting Sagital 320 4,5 mm T2 TRUFI squeezing Sagital 320 4,5 mm T2 TRUFI Cine defecation Sagital mm T2 TRUFI defecation Sagital 320 4,5 mm T2 TRUFI post-def. resting Sagital 320 4,5 mm Pelvic floor unit Retention and evacuation of the pelvic organs requires structural and functional integrity of the pelvic floor elements, which include: Ano-rectal neuromuscular system Pelvic organs (bladder, uterus (F) and rectum) Suspensory ligaments (ancorage points for muscles and viscera) Page 6 of 59

7 Muscles (support, contraction against ligaments; aperture/restraint) Osseous structures Nerves The pelvic floor unit is a multilayer system that provides active and passive support to the pelvic structures. A complex coordination and interaction is fundamental for pelvic floor function. The fascia are ancoraged to the pelvic bones. The ligaments are formed from fascia thickenings and both fascia and ligaments contribute for passive support of pelvic structures. The active support of pelvic floor depends of pelvic muscular system. Undameged structures are necessary for maintening pelvic floor functional activity Every pelvic compartment and structure is interdependent, interacting and compensating each other. MRI anatomy - Pelvic Compartments The pelvic compartments can be separated in three segments - anterior, middle and posterior. Fig. 1: Sagital slice showing the pelvic compartments Page 7 of 59

8 MRI anatomy - Pelvic Floor Layers The pelvic floor support structures can be divided in four layers, namely: Fig. 2: Left images are adapted from - Netter FH. (2014) Atlas of human anatomy. Saunders, 6th edition. References: Netter FH. (2014) Atlas of human anatomy. Saunders, 6th edition Superior (1st) Layer - endopelvic fascia: Adventitial layer that covers the pelvic diaphragm and envelops the pelvic organs It is covered by the peritoneum Gives support to the uterus and upper third of the vagina It is difficult to se on MRI - however, there are focal areas of thickening, named fascias, that can be discerned Page 8 of 59

9 Fig. 3 Fig. 4 Intermediate (2nd) layer - Pelvic Diaphragm The pelvic diaphragm is composed of the ischio-coccygeous muscle and the levator ani muscles (puborectalis, pubococcygeous and iliococcygeous). They represent one of the main pelvic floor support layers. Page 9 of 59

10 Fig. 5: Left image is adapted from Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) References: Shaaban AM, et al. (2015) Diagnostic Imaging gynecology. Elsevier Ischio-coccygeous muscle - forms the posterior part of the pelvic diaphragm, attaches to the ischion and the coccyx Puborectalis muscle - arises from the pubi rami, joins the pubococcygeous muscle and forms a sling posteriorly around the rectum Pubococcygeous muscle - arises from the pubic bone and attaches to the coccyx Iliococcygeous muscle - arises from the obturator internus fascia and inserts in the lateral aspect of the coccyx Page 10 of 59

11 Fig. 6: Left image is adapted from Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) References: Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) Fig. 7: b - bladder, r - rectum, u - urethra, IAS - internal anal sphincter, EAS - external anal sphincter. Right image is adapted from Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) References: Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) Page 11 of 59

12 Fig. 8: OI - obturator internus, u - urethra, v - vagina, r - rectum Intermediate (3rd) layer - Urogenital diaphragm The 3rd layer corresponds to a fibromuscular layer that lies directly below the pelvic diaphragm, which is triangular in shape. Fig. 9: Adapted from Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) References: Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) Page 12 of 59

13 A very important element to take notice in the MRI examination is the perineal body a fascial condensation posterior to the vagina, attachment site of perineal muscle and external anal sphincter. Fig. 10: left image is adapted from Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) References: Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) Superficial (4th) layer - External genital muscles Most superficial of the four layers, the extragenital muscles provide support to the inferior pelvic wall and exerts a role in sexual function. Posterior compartment - anal sphincters Envelops the anal canal and is composed of: Internal sphincter - layer of smooth muscle, continuation of rectal muscularis propria Inter-sphincteric space with longitudinal smooth muscle layer External sphincter - with striated muscle Page 13 of 59

14 Fig. 11: Lev Ani - levator ani muscle, OI - obturator internus, IAS - internal anal sphincter, EAS - external anal sphincter Right image is adapted from Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) References: Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) MRI anatomy - Measurements There are several points and lines of reference to evaluate the pelvic floor and different structures positions in the pelvis The most used lines are the pubococcygeal (PCL) and midpubic line (MPL) We used also the Anorectal Junction (AJR), Anorectal angle (ARA), H-Line and M-line. Page 14 of 59

15 Fig. 12: Measurement lines - summary References: Jonas Pubo-coccygeal line (PCL) - drawn between the inferior-posterior margin of the pubic symphysis to the anterior margin of the junction between first and second coccygeal segments; corresponds to levator plate; good correlation between PCL and classification of prolapse for anterior and middle compartments Fig. 13: Pubo-coccygeal line References: Jonas The PCL represents the levator plate. Organ prolapse is measured drawing a perpendicular line below and relative to the PCL for each compartment and respective organ (bladder - anterior, vagina - middle, ano-rectal junction - posterior) Perineal descent is present when it extends 3 cm below the PCL during evacuation Mid-pubic /Hymeneal line (MPL) - drawn through the longitudinal axis of the pubic bone and passing through its midequatorial point; it crosses the hymen level; moderate correlation with prolapse grading; Page 15 of 59

16 Fig. 14: Mid-pubic line This line represents an alternative measurement to the PCL for organ prolapse assessment, but it is mostly recommended for posterior compartment evaluation. Hiatus (H) line - drawn from the inferior margin of the symphsis pubis to the posterior margin of the puborectalis muscle sling. M line - extends perpendicularly from the PCL to the posterior end of the H line; allows for measurement of pelvic floor descent and subsequent grading Page 16 of 59

17 Fig. 15: M-line and H-line, relative to the PCL References: Jonas When there is weaking of the pelvic floor support structures, there is consequent hiatal relaxation and widening. The H line measures hiatal widening and the M line represents hiatal descent, in the context of pelvic relaxation. This measurement system, called HMO system, can also be used to measure organ prolapse, which can be defined as any organ that descends below the H line Ano-rectal junction - the anal canal typically measures between 2,5-4 cm; conventional measurement of the ano-rectal junction is 4 cm from the anus or at the point of intersection of anal canal with the lower third of the rectum, which form the ano-rectal angle Page 17 of 59

18 Fig. 16: Ano-rectal junction References: Jonas The ARJ represents the point at which posterior compartment descent and posterior organ prolapse are calculated, whichever grading technique previously described is chosen Ano-rectal angle - measured from the midline of the anal canal to a tangent to the posterior rectal wall; changes in the ano-rectal angle during squeezing and defecation allow estimation of the puborectalis muscle function Although there are established values for the ARA amplitude, the most important factor is the variation during functional assessment, where an ARA reduction during contraction and an increased ARA during defecation are expected, relative to the resting study ( ) Page 18 of 59

19 Fig. 18: Ano-rectal angle References: Jonas Pubo-rectalis impression - concavity formed by the distal posterior rectal wall due to normal contraction of the pubo-rectalis muscle Fig. 19 References: jonas Page 19 of 59

20 Pubo-rectalis impression should increase during voluntary contraction and relaxes during defecation (to allow for content evacuation). Paradoxal contraction of the puborectalis muscle during defecation is associated with ano-rectal dysfunction MRI dynamic evaluation - normal findings MRI dynamic evaluation is performed in three different stages: resting, squeezing (valsalva maneuver), defecation. Fig. 46 Resting Base of the bladder and cervix lie above the PCL ARJ lies 5 mm above PCL ARA - between Anal canal is closed Page 20 of 59

21 Fig. 44: Resting. Squeezing Rectum horizontalization ARJ moves superiorly and anteriorly mm ARA decreases 15-20º, reflecting normal puborectalis contraction Pubo-rectalis impression increases posterior concavity of the distal rectum Anal canal remains closed Page 21 of 59

22 Fig. 22: Squeezing - normal MRI sagital images Defecation ARJ moves downwards (less than 3 cm) below PCL ARA increases, reflecting puborectalis relaxation Pelvic floor descent should be less than 3,5 cm Anterior rectal wall becomes concave; puborectalis muscle impression is diminished Anal canal opens Rectal emptying should take less than 30 sec. Page 22 of 59

23 Fig. 23: Defecation - normal MRI sagital image Anal canal apperture - measured as an anterior-posterior diameter, during maximal defecation exertion; must be above 5 mm Page 23 of 59

24 Fig. 32 Page 24 of 59

25 Images for this section: Fig. 1: Sagital slice showing the pelvic compartments Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Fig. 2: Left images are adapted from - Netter FH. (2014) Atlas of human anatomy. Saunders, 6th edition. Netter FH. (2014) Atlas of human anatomy. Saunders, 6th edition Page 25 of 59

26 Fig. 3 Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Fig. 4 Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Page 26 of 59

27 Fig. 5: Left image is adapted from Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) Shaaban AM, et al. (2015) Diagnostic Imaging gynecology. Elsevier Fig. 6: Left image is adapted from Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) Page 27 of 59

28 Fig. 7: b - bladder, r - rectum, u - urethra, IAS - internal anal sphincter, EAS - external anal sphincter. Right image is adapted from Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) Fig. 12: Measurement lines - summary Jonas Page 28 of 59

29 Fig. 13: Pubo-coccygeal line Jonas Page 29 of 59

30 Fig. 14: Mid-pubic line Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Page 30 of 59

31 Fig. 15: M-line and H-line, relative to the PCL Jonas Fig. 16: Ano-rectal junction Jonas Page 31 of 59

32 Fig. 17: Ano-rectal junction Jonas Fig. 18: Ano-rectal angle Jonas Page 32 of 59

33 Fig. 19 jonas Fig. 20: MRI dynamic evaluation of defecation Jonas Page 33 of 59

34 Fig. 21: Resting - normal MRI sagital images Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Fig. 22: Squeezing - normal MRI sagital images Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Page 34 of 59

35 Fig. 23: Defecation - normal MRI sagital image Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Page 35 of 59

36 Fig. 24 Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Fig. 25: Arrows - rectal intussusception Left image - schematics of rectal intussusception Middle Image - schematics of rectal prolapse Jonas Page 36 of 59

37 Fig. 26 Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Fig. 27 Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Page 37 of 59

38 Fig. 28 Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Fig. 29 Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Page 38 of 59

39 Fig. 30 Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Fig. 31 Centro Hospitalar Lisboa Central, Hospital Curry Cabral - Lisbon/PT Page 39 of 59

40 Findings and procedure details Morphologic Abnormalities Rectocele - bulging of the anterior rectal wall against the posterior vaginal wall. Small rectoceles are frequent in asymptomatic women and may represent a normal variant. Large rectoceles (> 2 cm) have a strong association with evacuation difficulty. Rectoceles may contribute to passive leakage after incomplete evacuation. Herniation of the pelvic peritoneal sac through the recto-genital space below de pubococcigeal ligament or recto-vaginal septum at the level or below the lower third of the vagina; it may contain fat (peritoneocele), small bowel or a sigmoid segment (sigmoidocele). Fig. 47: Arrow - rectocele. Page 40 of 59

41 Fig. 48: Arrows - rectoceles Enterocele -Herniation of the pelvic peritoneal sac through the recto-genital space below de pubo-coccigeal ligament or recto-vaginal septum at the level or below the lower third of the vagina; it may contain fat (peritoneocele), small bowel or a sigmoid segment (sigmoidocele). Page 41 of 59

42 Fig. 33: Arrow - enterocele Page 42 of 59

43 Fig. 34: CINE RM. Enterocele formation during defecation. Cystocele - Bladder floor descent below the inferior border of the symphysis pubis (> 1 cm) Page 43 of 59

44 Fig. 35: Arrows - cystoceles Page 44 of 59

45 Fig. 36: Cc - cystocele, Up - uterine prolapse Functional abnormalities Descending perineum / pelvic floor descent - excessive caudal movement of the pelvic floor during defecation. Posterior compartment abnormality characterized by descent of the ano-rectal junction more than 3 cm below the PCL, often associated with middle and anterior pelvic floor Page 45 of 59

46 descent as well as rectocele, intussusception, organ prolapse and/or obstruction to defecation. Pelvic floor descent is measured with the H line (normal diameter 5-6 cm). Fig. 24 Intussusception and prolapse - defined as any organ descent beyond the H-line. Rectal prolapse corresponds to a full thickness extrusion of the rectal wall beyond the anal verge. On the other hand, intussusception, also termed internal rectal prolapse, does not protrude through the anus, but is confined to the rectum (intrarectal) or protrudes to the anal canal (intra-anal). It is often associated with rectocele and/or enterocele, and usually originates 6-8 cm above the anal verge, where the main mucosal folds are located. It is generally circumferential, although it may have a focal presentation (often of the anterior rectal wall). Page 46 of 59

47 Fig. 25: Arrows - rectal intussusception Left image - schematics of rectal intussusception Middle Image - schematics of rectal prolapse References: Jonas Fig. 37: Arrows - rectal intussusception Spastic pelvic syndrome /Dyskinetic Puborectalis / Anismus- inability of an abnormally contracted puborectalis to relax during defecation does not allow for a normal evacuation. Anismus is a common cause of obstruction to defecation that is frequently overlooked. It may be associated with pelvic floor descent and/or pubo-rectalis muscular hypertrophy. Page 47 of 59

48 Fig. 38: Arrow - persistence of pubo-rectalis muscle impression during defecation Fig. 39 Paradoxical pubo-rectalis muscle contraction during defecation associated with spastic pelvic syndrome Page 48 of 59

49 Fig. 40: Arrow - persistence of pubo-rectalis muscle impression during defecation Page 49 of 59

50 Fig. 50: CINE RM. Persistence of puborectalis muscle impression during defecation. Absent / insufficient anal canal aperture - associated withpelvic spastic syndrome Page 50 of 59

51 Fig. 41: CINE RM. Spastic pelvic syndrome - the pelvic unit shows low mobility, the ano-rectal angle doesn't widen during defecation attempts and there is persistence of the pubo-rectalis muscle impression. Defecation was unsuccessful during examination. Page 51 of 59

52 Fig. 42: CINE RM. Compared with the previous example, there is pelvic floor movement with perineal descent, formation of anterior rectocele and insufficient/absent apperture of the anal canal. Defecatory attempts are unsuccessful. Case 1 - Fecal incontinence 88 year-old woman, with rectal incontinence for soft stools and prolapse. Page 52 of 59

53 Images show an open anal canal at resting, that widens during defecation, associated with severe perineal descent, rectal verticalization and prolapse, uterine prolapse (it can be seen beyond the bladder at maximum defecatory effort) and cystocele. The pelvic compartments are intricately related with each another. This case illustrates multicompartment dysfunction that is most severe at the posterior segment, with defecatory incontinence. Fig. 29 Page 53 of 59

54 Fig. 43: CINE RM - Defecatory phase Case 2 - Posterior pelvic floor dysfunction 56 year-old woman, with terminal obstipation During defecation, a significant rectocele is formed, accompanied by perineal descent. The anal canal has an insufficient apperture (< 5 mm). These findings, which are compatible with posterior pelvic floor dysfunction, contribute to the obstruction to defecation that the patient complaints. Page 54 of 59

55 Fig. 30 Page 55 of 59

56 Fig. 49: CINE RM. Defecatory phase. MRI findings summary - what the clinican needs to know Page 56 of 59

57 Fig. 31 Page 57 of 59

58 Conclusion MRI is a non-invasive, non-ionizing radiation technique, which can be an important auxilliary tool for pelvic floor anatomy and functional evaluation, thanks to its extraordinary capabilities regarding tissue contrast It is a technique that, when adequately integrated with prior clinical evaluation and exclusion of organic disease, may have na invaluable role in the diagnosis, therapeutic guidance and follow-up of pelvic floor dysfunction disorders Magnetic resonance permits evaluation of the three pelvic compartments and, as we demonstrated, more than one compartment are frequently affected Assessment of MRI defecography has a good inter-observer correlation Page 58 of 59

59 References Li M, et al. Association of compartment defects in anorectal and pelvic floor dysfunction with female outlet obstruction constipation (OOC) by dynamic MR defecography. European review for medical and pharmacological sciences (2015) 19: Aminah NA, et al. review of functional pelvic floor imaging modalities and their effectiveness. Clinical Imaging (2015) Khatri G. Magnetic resonance imaging of pelvic floor disorders. Topics in magnetic resonance imaging (2014) 23 (4): Pizzoferrato A-C, et al. Dynamic magnetic resonance imaging and pelvic floor disorders: how and when?. European journal of obstetrics and gynecology and reproductive biology (2014) 181: Brandão A, Ianez P. MR imaging of the pelvic floor - defecography. Magn Reson Imaging Clin N Am (2013) 21: Maccioni F. Functional disorders of the ano-rectal compartment of the pelvic floor: clinical and diagnostic value of dynamic MRI. Abdominal Imaging (2012) Reiner CS, Weishaupt D. Dynamic pelvic floor imaging: MRI techniques and imaging parameters. Abdominal Imaging (2012) Netter FH. Atlas of human anatomy. Saunders, 6th edition (2014) Shaaban AM, et al. Diagnostic Imaging gynecology. Elsevier (2015) Page 59 of 59