Spectrum of lesions involving the petrous apex

Transcription

1 Spectrum of lesions involving the petrous apex Poster No.: C-1796 Congress: ECR 2010 Type: Educational Exhibit Topic: Head and Neck Authors: I. Alba, A. Paniagua Bravo, J. A. Blanco, L. Ibañez, J. C. Albillos, E. Fraile; Madrid/ES Keywords: petrous apex, petrous apex lesions, temporal bone 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 67

2 Learning objectives The aim of the study is to review and illustrate the MR and CT appearance of different spectrum of lesions that can involve petrous apex. These lesions can present with various symtoms and signs, depending on the location, size of the same and even the nature of the pathologic process. Some of them are incidental discovery and needn t treatment, others are frecuent features, and not be confused with real injuries Clinical symptoms include, hearing loss (the most common), vestibular dysfunction, headache, tinnitus, otorrhea, facial palsy and diplopia The petrous apex cannot be directly examined, so imaging plays a key role in the evaluation of lesions in this area. CT of the temporal bone provides a detailed information architecture petrous apex. As in any bone, there are different patterns of involvement that help distinguish between benign and aggressive. Further, another advantage of this technique is that you can locate the proximity of the injury to critical neural or vascular structures MRI provides an important information on injuries at the petrous apex, as many of them due to their specific nature, they behave in specific way in each sequence and they have different patterns of enhancement based on the type of lesion CT and MR are complementary and both are needed to reach a more accurate diagnosis Radiologists must know and interpret the imaging of this specific location, which does not allow a direct visual inspection, because some lesions do not require surgery and some of them needn t treatment and are merely incidental Background Anatomy Page 2 of 67

3 The petrous apex is a pyramid-shaped structure that is the most medial aspect of the temporal bone,anteromedial to the inner ear and lateral to the petro-occipital fissure (Fig A). The base of the pyramid is the otic capsule, semi-canal of the tensor tympani and the petrous carotid artery. The superior surface extends from the arcuate eminence to the precavernous carotid artery and Meckel s cave. The internal auditory meatus divides it into larger anterior and a smaller posterior compartiments, the first one principally consisting of bone marrow or air cells and the other derived from the dense otic capsule. The internal auditory canal is located in the middle of the medial surface of the pyramid shape in an angle of near 45º The posterior surface faces the cerebellopontine angle. At the inferior aspect of the petrous apex are located the jugular fossa and inferior petrosal sinus. The internal carotid artery enters the petrous apex along the inferior surface via the carotid canal The petrous apex is primarily composed of bone marrow, but in approximately onethird ( 9-35 % ) of subjects has pneumatizacion and are aerated by tracts that directly communicate with the middle ear cleft and mastoid The main lesions affecting the petrous apex, benign (some are seudolesiones) and malignant, are summarized in Table 1, indicating the characteristics and behavior from the radiological point of view, on CT and MRI Table 1 LESION MR MR MR CT FSE T2 SE T1 SET1+ C (pattern of destruction) Cholesterol Hyperintense Hyperintense No Smooth granuloma enhancement erosion OTHER Hypointenese on fat saturated MR sequences Petrous apicitis Hyperintense Hypointenese Rim Destroyed septae enhancement Page 3 of 67

4 CSF cyst/ Hyperintense Hypointenese No Smooth enhancement cephalocele erosion May connect to Meckel s cave Epidermoid Hyperintense Hypointenese No Smooth enhancement erosion Hyperintense on FLAIR and Diffusionweighted Effusion Hyperintense Hypointenese Enhancement Intact or Isointense septation Asymmetric Hypointenese Hyperintense Some Marrow on Air cells on pneumatization lesion side contralateral enhancement side Carotid aneurysm Hyperintense Hypointenese*Enhancement Smooth Hyperintense" * (new thrombus) expansion " (older thrombus) Paget s Disease Hypointense Hypointense No Depends of Ground enhancement the phases glass demineralization at first and bone thickening at the end Fibrous dysplasia Hypointense Hypointense No Ground Increased enhancement glass bone demineralization volume Chondro/ osteo Hypointense Isointense Enhancement Infiltrative Remnants of eroded bone hetereogeneus sarcoma Chordoma Hyperintense Hypointenese Enhancement Bone destruction or Isointense Metastasis Depends on Depends on Enhancement Bone primary primary ersosion Residual bone fragments Page 4 of 67

5 Meningioma Hyperintense/ Hyperintense Enhancement Hiperostosis Dural tail Isointense or Isointense SchwannomaHyperintense Isointense or hypo Calcification Enhancement Dilation of Centered in IAC IAC Langerhans Slightly Isointense cell histiocytosis Hyperintense Enhancement Bone destruction Cholesteatoma Hyperintense Hypointenese No Bening or enhancement agressive Page 5 of 67

6 Fig.: Axial CT image through the inferior portion of the left temporal bone in bone window shows the bounderies of the petrous apex formed by the petro-occipital fissure medially and the petro-sphenoidal fissure anteriorly an the inner structures laterally ( partially displayed), and the petrous carotid canal,crossing the petrous apex perpendicular References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 6 of 67

7 Imaging findings OR Procedure details The differential diagnosis of petrous apex lesions includes congenital entities ( asymmetric fatty marrow, cholesteatoma), infection (apical petrositis) benign obstructive processes (effusion, mucocele,cholesterol granuloma), benign tumor (meningioma, schwannoma), malignant tumor (chordoma,chondrosarcoma,osteosarcoma, metastasis) and miscellaneous lesions ( histiocytosis X, Paget disease,fibrous dysplasia, petrous carotid artery aneurysm,meningocele/cephalocele) Congenital entities Asymmetric fatty marrow Diploic fatty marrow in an asymetrically non neumatized or little pneumatized petrous apex is characterized by increased T1 weighted signal, and may be confused with an injury, but the CT shows that this is an incidental finding that does not need treatment. Page 7 of 67

8 Fig.: Asymmetric fatty marrow in a patient without symptoms related. CT shows a normal pneumatized right petrous apex and a nonexpansile, nonpneumatized left petrous apex with fatty marrow References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 8 of 67

9 Fig.: Asymmetric fatty marrow at the right petrous apex. A 16 yeard-old girl with headache. Incidentally, T1 w Mri reveals asymmetric increased signal at the right petrous apex( fig 1 ). Axial CT confirms the presence of diploic fat in the right petrous apex and pneumatization of the left petrous apex(fig 2). There is no evidence of an underlying lesion. References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 9 of 67

10 Fig.: Asymmetric fatty marrow at the right petrous apex. A 16 yeard-old girl with headache. Incidentally, T1 w Mri reveals asymmetric increased signal at the right petrous apex(fig1). Axial CT confirms the presence of diploic fat in the right petrous apex and pneumatization of the left petrous apex(fig2). There is no evidence of an underlying lesion. References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Cholesteatoma Petrous apex cholesteatoma is a rare entity that icludes 4% to 9% of all petrous apex lesions. It can be acquired or congenital. Involvement of the petrous apex is caused by contiguity of cholesteatoma involving the middle ear or mastoid. CT shows a low density mass that does not enhance but demonstrates smooth bone erosion. The T1 and T2 weighted MRI characteristics are the same as CSF, but in the sequences FLAIR and diffusion are hiperintense, not being so CSF and arachnoid cysts. If the lesion enhances, it is very likely to be a squamous cell carcinoma. Surgical excision or exteriorization is the treatment of choice Page 10 of 67

11 Fig.: Cholesteatoma. CT with bone window into a woman of 43 years with hearing loss of conduction. It shows a destructive lesion centered in the middle ear and mastoid process progresses to the petrous apex. Surgical excision was performed. Histologic examination confirmed cholesteatoma References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Infection Apical petrositis Page 11 of 67

12 It is a rarely encountered entity today, being a rare complication of otitis media, that results from spread of infection to the petrous apex throughair-cells tracts in the temporal bone and associated with a high morbidity and mortality rates in the pre-antibiotic era. CT demonstrate opacification and destruction of the petrous apex air cell system and MRI may show a hypointense lesion with rim enhancement on T1w images and a hyperintense signal on T2. Treatment consists of intravenous antibiotics Benign obstructive processes Effusion Effusion arise as a result of infection in the middle ear or mastoid wich consequent trapping of fluid in the petrous apex and only can be found in pneumatized petrous apex. The incidence of this lesion is 1 %. CT scan shows occupation of the air cells, without coalescent and appear Hypeintense on T2Wi and hypointense on T1 Wi.Patients may be asymptomatic or symptomatic, with hearing loss, positional vertigo, headache... These should be treated with oral antibiotics and steroids Page 12 of 67

13 Fig.: Effusion, trapped fluid. A 25-year-old man with dizzines and headache. CT scans shows nonexpansile fluid attenuation opacification of the pneumatized left petrous apex without evidence of trabecular disruption.the predominant low signal indicates fluid content. This was an incidental finding. References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Cholesterol granuloma This lesion has been reported along the entire temporal bone, middle ear,mastoid and petrous apex. It is a rare, benign expanding lesion, whose term means a foreign body and is a cyst with a thick fibrous capsule filled with a brown fluid, which is formed by degradation blood elements, such as lipids and cholesterol crystals. Diagnosis requires imaging studies with both CT scans and MR. Cholesterol granuloma is non enhancing in both imaging methods. In CT images, the margins of the lesion are sharp with bone erosion present frequently, and the contralateral petrous apex is well pneumatized. RM is hyperintense on all sequences T1, T2 and FLAIR. Symtoms Page 13 of 67

14 do not occur until it has been relatively large. The main symptoms are hearing loss and vertigo in one third of cases, followed by tinnitus and otalgia. If the lesion is asymptomatic, only checks are done by imaging techniques, but if it grows or is symptomatic surgical treatment is performed Fig.: Cholesterol Granuloma. Male 16 years of age who complains of episodes of visual disturbance and headache underwent conventional MRI and diffusion. There is a hyperintense lesion on T2 FSE and FLAIR sequence (Figures 1 and 2) non-aggressive edge and without enhancement. In the study of diffusion (fig 3) was not hyperintense, Page 14 of 67

15 which ruled out that it is a cyst epidermide. The diagnostco to think, as a first possibility is a cholesterol granuloma References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Fig.: Cholesterol granuloma. Male 16 years of age who complains of episodes of visual disturbance and headache underwent conventional MRI and diffusion. There is a hyperintense lesion on T2 FSE and FLAIR sequence (Figures 1 and 2) non-aggressive edge and without enhancement. In the study of diffusion (fig 3) was not hyperintense, which ruled out that it is a cyst epidermide. The diagnostco to think, as a first possibility is a cholesterol granuloma Page 15 of 67

16 References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Fig.: Cholesterol granuloma. Male 16 years of age who complains of episodes of visual disturbance and headache underwent conventional MRI and diffusion. There is a hyperintense lesion on T2 FSE and FLAIR sequence (Figures 1 and 2) non-aggressive edge and without enhancement. In the study of diffusion (fig 3) was not hyperintense, which ruled out that it is a cyst epidermide. The diagnostco to think, as a first possibility is a cholesterol granuloma References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 16 of 67

17 Benign tumor Meningioma Meningiomas are the most frequent benign tumors and occur in any location where there is meningeal lining the decks, and that includes the petrous apex. These lesions are extraparenchymal and are more commonly discovered in middle-aged and elderly woman. Besides the female gender, the only known risk factor is the focal exposure to radiation (radiotherapy). MRI with gadolinium is the procedure of choice when evaluating meningiomas, being able to detect lesions less than 3 mm, appear as sessile, extra-axial mass with accompanying dural tails. These lesions are most commonly isointense on T1, and enhance with gadolinium, also are iso to hyperintense on T2 images. All the petroclival meningiomas may have symptoms : headache, hearing loss, vertigo and deficits in cranial nerves; trigeminal, cochlear and vestibular Surgery and radiation are the treatments for symptomatic meningiomas, doing one or the other or even both in combination as a function of size and adjacent neurovascular compromise Page 17 of 67

18 Fig.: Meningioma, whose wide base of implantation is on the medial edge of the pyramid which forms the petrous apex. The lesion shows a calcified meningeal thickening (Fig. 1), filling the tank side to the pons, demonstrating diffuse enhancement typical of meningiomas (due to its vascularization), in TC (fig2) and MR (fig3) References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 18 of 67

19 Fig.: Meningioma, whose wide base of implantation is on the medial edge of the pyramid which forms the petrous apex. The lesion shows a calcified meningeal thickening (Fig. 1), filling the tank side to the pons, demonstrating diffuse enhancement typical of meningiomas (due to its vascularization), in TC (fig2) and MR (fig3) References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 19 of 67

20 Fig.: Meningioma, whose wide base of implantation is on the medial edge of the pyramid which forms the petrous apex. The lesion shows a calcified meningeal thickening (Fig. 1), filling the tank side to the pons, demonstrating diffuse enhancement typical of meningiomas (due to its vascularization), in TC (fig2) and MR (fig3) References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Schwannoma Page 20 of 67

21 Petrous apex schwannomas may originate from cranial nerves IV,V,VI,VII or VIII. Involvement of the petrous apex occurs by direct extension from nearby locations, not being itself often leaves the petrous apex. The affectation is most common in the vestibular division of the eighth cranial pair in its portion intracanlicular, with masses that enhance with contrast studies with morphology in ice cream cone with the cone located at the IAC and the scoop on the angle cerebellopontine. These tumor grow slowly; 1-2 mm per year. They are hypointense on T1 and hyperintense on T2WI with respect to the adjacent parenchyma and have a significant enhancement. Fig.: Vestibular Schwannoma. Large left internal auditory canal-cerebellopontine angle mass. This tumor is slightly hypointense to brain on the axial T1weighted ( fig 1) MR and enhances uniformly on the postgadolinium images ( fig2). Axial High resolution T2 weighted MRI shows a rim of CFS ( fig 3 ) between the apex of the mass in the fundus and the cochlear aperture References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 21 of 67

22 Fig.: Vestibular Schwannoma. Large left internal auditory canal-cerebellopontine angle mass. This tumor is slightly hypointense to brain on the axial T1weighted ( fig 1) MR and enhances uniformly on the postgadolinium images ( fig2). Axial High resolution T2 weighted MRI shows a rim of CFS ( fig 3 ) between the apex of the mass in the fundus and the cochlear aperture References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 22 of 67

23 Fig.: Vestibular Schwannoma. Large left internal auditory canal-cerebellopontine angle mass. This tumor is slightly hypointense to brain on the axial T1weighted ( fig 1) MR and enhances uniformly on the postgadolinium images ( fig2). Axial High resolution T2 weighted MRI shows a rim of CFS ( fig 3 ) between the apex of the mass in the fundus and the cochlear aperture References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Malignant tumor Chordoma Page 23 of 67

24 These are aggressive tumors that originate from embriologic remnants of the notochord at the mid line from clivus to sacro. CT demonstrates a locally destructive lesion, centered at the clivus that may invade the petrous apex, with moderate to marked enhancement with contrast. MRI helps determine the extent of the enfermedad.chordomas are hipointesos in T1 and hyperintense on T2. Contrast enhancement has a honeycomb pattern. A combination of surgery and radiation therapy is generally required Chondrosarcoma These tumors are rare malignancies that arise from embryologic cartilage rests along the sphenopetroclival fissure and are often associated with other syndromes such as Maffucci, Ollier, Paget...Headache,diplopia and other nonspecific symptoms appear as clinical manifestation. CT shows location of origin, destructive and "pop corn" pattern, are seen as hotbeds of calcicacion points concerning calcified chondroid matrix.chondrosarcomas are usually hypo to isointense with T1W MRI, hyperintense on T2 w MRI and demonstrates heterogeneus enhancement. Surgical management is the mainstay of therapy Osteosarcoma Osteosarcomas and rhabdomyosarcomas are very aggressive tumors that may also affect the petrous apex, producing bone destruction with tumour bone formation (osteoid) and enhancement of the non -mineralized tumour on MRI, being mildly hyperintense T2 w signal and hypointense on T1 MRI. The mainstay of treatment for osteosarcoma of the skull base is surgery, but radiation therapy is an important adjunctive therapy in their manegement Page 24 of 67

25 Fig.: Osteosarcoma. 5 year old child with otitis media and otorrhea that is not curable with antibiotics. Axial CT image ( Fig 1) displayed in bone window shows a destructive lesion (arrow) in more lateral and anterior aspect of the pyramid, surrounding the carotid canal, with large occupation of the tympanic cavity and mastoid air cell The axial T1-weighted images without ( Fig 2) and with (Fig 3, fat supressed) contrast enhancement demonstrate a large area of anormal signal intensity involving de anterior and lateral left petrous apex. The axial T1 weighted without contrast, is better to differentiate the lesion from the postobstructive changes. Enhancing mass in the petrous apex is consistent with osteosarcoma References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 25 of 67

26 Fig.: Osteosarcoma. 5 year old child with otitis media and otorrhea that is not curable with antibiotics. Axial CT image ( Fig 1) displayed in bone window shows a destructive lesion (arrow) in more lateral and anterior aspect of the pyramid, surrounding the carotid canal, with large occupation of the tympanic cavity and mastoid air cell The axial T1-weighted images without ( Fig 2) and with (Fig 3, fat supressed) contrast enhancement demonstrate a large area of anormal signal intensity involving de anterior and lateral left petrous apex. The axial T1 weighted without contrast, is better to differentiate the lesion from the postobstructive changes. Enhancing mass in the petrous apex is consistent with osteosarcoma References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 26 of 67

27 Fig.: Osteosarcoma. 5 year old child with otitis media and otorrhea that is not curable with antibiotics. Axial CT image ( Fig 1) displayed in bone window shows a destructive lesion (arrow) in more lateral and anterior aspect of the pyramid, surrounding the carotid canal, with large occupation of the tympanic cavity and mastoid air cell The axial T1-weighted images without ( Fig 2) and with (Fig 3, fat supressed) contrast enhancement demonstrate a large area of anormal signal intensity involving de anterior and lateral left petrous apex. The axial T1 weighted without contrast, is better to differentiate the lesion from the postobstructive changes. Enhancing mass in the petrous apex is consistent with osteosarcoma References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Metastasis Page 27 of 67

28 The petrous apex is the part of the temporal bone in which are deposited more frequently hematogenously metastatic cells, due to slow flow in that location, which in order of frequency derived from breast, lung, prostate, melanoma and kidney. Adenocarcinoma being the most common histological subtype and age of presentation, like the rest of metastasis, is usually between 50 and 70 years. Most of them have a very aggressive bone destruction and enhancement after contrast administration in MRI and CT, but always depend on the characteristics of the primary lesion Treatment often consists of palliative therapy Miscellaneous lesions Histiocytosis X These are rare and idiopathic tumors caused by the proliferation of mature eosinophils and have different ways of presentation, one is located and which is more frequent in children (5 to 15 years) and is known as eosinophilic granuloma, and diffuse involvement of another disease that is Hand -Schuller- Christian Frontal and temporal bones are the most commonly affected regions in the skull and skull base. On CT eosinophilic granuloma shows a lytic lesion without sclerosis of the margins but not overly destructive appearance. MR imaging demonstrates a solid lesion with enhancing soft tissue edema, leading to simulate osteomyelitis or a malignant tumor. Solitary lesions are typically treated with curettage or excision Page 28 of 67

29 Fig.: Langerhans cell histiocytosis. 8 year old child with headache. The CT scan (Fig 1, Fig 2) shows litic lesion smooth margin that comes from the petrous apex and extends to the medial side of the pyramid, and invades the carotid canal. Axial FSE T2 fat saturated MRi (Fig 3), coronal SET1 (Fig 4) and axial SET1 fat sat with paramagnetic contrast (Fig 5), confirms that it is a vascularized solid lesion invades adjacent structures. The pathological findings confirmed that it was langerhans cell histiocytosis(eosinophilic granuloma). Isolated involvement of the petrous apex is not common and a middle ear or mastoid location is more typical Page 29 of 67

30 References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Fig.: Langerhans cell histiocytosis. 8 year old child with headache. The CT scan (Fig 1, Fig 2) shows litic lesion smooth margin that comes from the petrous apex and extends to the medial side of the pyramid, and invades the carotid canal. Axial FSE T2 fat saturated MRi (Fig 3), coronal SET1 (Fig 4) and axial SET1 fat sat with paramagnetic contrast (Fig 5), confirms that it is a vascularized solid lesion invades adjacent structures. The pathological findings confirmed that it was langerhans cell histiocytosis(eosinophilic granuloma). Isolated involvement of the petrous apex is not common and a middle ear or mastoid location is more typical References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 30 of 67

31 Fig.: Langerhans cell histiocytosis. 8 year old child with headache. The CT scan (Fig 1, Fig 2) shows litic lesion smooth margin that comes from the petrous apex and extends to the medial side of the pyramid, and invades the carotid canal. Axial FSE T2 fat saturated MRi (Fig 3), coronal SET1 (Fig 4) and axial SET1 fat sat with paramagnetic contrast (Fig 5), confirms that it is a vascularized solid lesion invades adjacent structures. The pathological findings confirmed that it was langerhans cell histiocytosis(eosinophilic granuloma). Isolated involvement of the petrous apex is not common and a middle ear or mastoid location is more typical References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 31 of 67

32 Bone dysplasias As in any part of the bones of the skull base, bone dysplasias can affect the petrous apex, most of them affecting more bones together. In Paget's disease there are different stages of involvement, starting with a ground glass demineralization or osteoporosis circumscribed and ending in a blast phase of thickening and heterogeneity, roughlooking. Furthermore, fibrous dysplasia is shown in younger patients, appreciating a diffusely increased bone volume that affects the entire craniofacial region. In both cases, the CT has greater sensitivity and even specificity for diagnosis comparing it with the resonance Cephalocele The cephaloceles of the petrous apex are believed to arise from the protrusion of the arachnoid or dura from the Meckel s cave. All the lesions are centered in the posterolateral portion of the Meckel s cave and has sharply defined osseous margins with homogeneous central low attenuation on CT. In all cases, the cyst appears contiguous with Meckel s cave The portion that affects the petrous apex has a posterior and inferior direction, sometimes reaching down that affect the posterior wall of the carotid canal On T1 MRI the cyst is hypointense with mild ring enhancement if you do it with intravenous contrast, logically presents high signal on T2 MRI,like CSF. They are usually asymptomatic and require no treatment Page 32 of 67

33 Fig.: Cephalocele. A 43-year old man presented with right third and fifth cranial neuropathies. Axial CT scans, bone algorithm ( Fig 2 ) and soft tissue window (Fig 1) reveals a sharply marginated expansile right petrous apex mass ( black arrow). Axial ( Fig 3) T2-weighted FSE and axial SE T1 (Fig 4) MR i confirms that the expansile mass revealed on CT studies is a cyst ( yellow arrows) with CSF signal intensity extending from Meckel s cave into the petrous apex References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 33 of 67

34 Fig.: Cephalocele. A 43-year old man presented with right third and fifth cranial neuropathies. Axial CT scans, bone algorithm ( Fig 2 ) and soft tissue window (Fig 1) reveals a sharply marginated expansile right petrous apex mass ( black arrow). Axial ( Fig 3) T2-weighted FSE and axial SE T1 (Fig 4) MR i confirms that the expansile mass revealed on CT studies is a cyst ( yellow arrows) with CSF signal intensity extending from Meckel s cave into the petrous apex References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 34 of 67

35 Fig.: Cephalocele. A 43-year old man presented with right third and fifth cranial neuropathies. Axial CT scans, bone algorithm ( Fig 2 ) and soft tissue window (Fig 1) reveals a sharply marginated expansile right petrous apex mass ( black arrow). Axial ( Fig 3) T2-weighted FSE and axial SE T1 (Fig 4) MR i confirms that the expansile mass revealed on CT studies is a cyst ( yellow arrows) with CSF signal intensity extending from Meckel s cave into the petrous apex References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 35 of 67

36 Fig.: Bilateral Cephalocele. MR image shows a bilateral cyst of CSF signal intensity extending inferiorly into the petrous apex from Meckel s cave ( Fig 2). Axial CT scan ( Fig 1 ) shows bilateral expansile lesion with smooth margins being higher on the right References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Page 36 of 67

37 Fig.: Bilateral Cephalocele. MR image shows a bilateral cyst of CSF signal intensity extending inferiorly into the petrous apex from Meckel s cave ( Fig 2). Axial CT scan ( Fig 1 ) shows bilateral expansile lesion with smooth margins being higher on the right Page 37 of 67

38 References: I. Alba; Radiodiagnostico, Hospital infanta sofia, Madrid, SPAIN Petrous carotid artery aneurysm Is thought to originate from weak areas of the arterial blood vessel wall but are often associated with three cases, congenital, mycotic and traumatic history, as almost all aneurysms. They are usually fusiform and are clinically asymptomatic or nonspecific symptoms like other injuries in that location such as hearing loss, headache, tinnitus and neurological deficits in cranial nerves In CT you can see erosion and remodeling of smooth edges of the petrous apex by aneurysmal dilatation. MRI often shows a flow void in that location. Conventional angiography is the gold santandard Images for this section: Page 38 of 67

39 Fig. 1: Axial CT image through the inferior portion of the left temporal bone in bone window shows the bounderies of the petrous apex formed by the petro-occipital fissure medially and the petro-sphenoidal fissure anteriorly an the inner structures laterally ( partially displayed), and the petrous carotid canal,crossing the petrous apex perpendicular Page 39 of 67

40 Fig. 2: Asymmetric fatty marrow at the right petrous apex. A 16 yeard-old girl with headache. Incidentally, T1 w Mri reveals asymmetric increased signal at the right petrous apex( fig 1 ). Axial CT confirms the presence of diploic fat in the right petrous apex and pneumatization of the left petrous apex(fig 2). There is no evidence of an underlying lesion. Page 40 of 67

41 Fig. 3: Asymmetric fatty marrow in a patient without symptoms related. CT shows a normal pneumatized right petrous apex and a nonexpansile, nonpneumatized left petrous apex with fatty marrow Page 41 of 67

42 Fig. 4: Asymmetric fatty marrow at the right petrous apex. A 16 yeard-old girl with headache. Incidentally, T1 w Mri reveals asymmetric increased signal at the right petrous apex(fig1). Axial CT confirms the presence of diploic fat in the right petrous apex and pneumatization of the left petrous apex(fig2). There is no evidence of an underlying lesion. Page 42 of 67

43 Fig. 5: Effusion, trapped fluid. A 25-year-old man with dizzines and headache. CT scans shows nonexpansile fluid attenuation opacification of the pneumatized left petrous apex without evidence of trabecular disruption.the predominant low signal indicates fluid content. This was an incidental finding. Page 43 of 67

44 Fig. 6: Osteosarcoma. 5 year old child with otitis media and otorrhea that is not curable with antibiotics. Axial CT image ( Fig 1) displayed in bone window shows a destructive lesion (arrow) in more lateral and anterior aspect of the pyramid, surrounding the carotid canal, with large occupation of the tympanic cavity and mastoid air cell The axial T1weighted images without ( Fig 2) and with (Fig 3, fat supressed) contrast enhancement demonstrate a large area of anormal signal intensity involving de anterior and lateral left petrous apex. The axial T1 weighted without contrast, is better to differentiate the lesion from the postobstructive changes. Enhancing mass in the petrous apex is consistent with osteosarcoma Page 44 of 67

45 Fig. 7: Osteosarcoma. 5 year old child with otitis media and otorrhea that is not curable with antibiotics. Axial CT image ( Fig 1) displayed in bone window shows a destructive lesion (arrow) in more lateral and anterior aspect of the pyramid, surrounding the carotid canal, with large occupation of the tympanic cavity and mastoid air cell The axial T1weighted images without ( Fig 2) and with (Fig 3, fat supressed) contrast enhancement demonstrate a large area of anormal signal intensity involving de anterior and lateral left petrous apex. The axial T1 weighted without contrast, is better to differentiate the lesion from the postobstructive changes. Enhancing mass in the petrous apex is consistent with osteosarcoma Page 45 of 67

46 Fig. 8: Osteosarcoma. 5 year old child with otitis media and otorrhea that is not curable with antibiotics. Axial CT image ( Fig 1) displayed in bone window shows a destructive lesion (arrow) in more lateral and anterior aspect of the pyramid, surrounding the carotid canal, with large occupation of the tympanic cavity and mastoid air cell The axial T1weighted images without ( Fig 2) and with (Fig 3, fat supressed) contrast enhancement demonstrate a large area of anormal signal intensity involving de anterior and lateral left petrous apex. The axial T1 weighted without contrast, is better to differentiate the lesion from the postobstructive changes. Enhancing mass in the petrous apex is consistent with osteosarcoma Page 46 of 67

47 Fig. 9: Langerhans cell histiocytosis. 8 year old child with headache. The CT scan (Fig 1, Fig 2) shows litic lesion smooth margin that comes from the petrous apex and extends to the medial side of the pyramid, and invades the carotid canal. Axial FSE T2 fat saturated MRi (Fig 3), coronal SET1 (Fig 4) and axial SET1 fat sat with paramagnetic contrast (Fig 5), confirms that it is a vascularized solid lesion invades adjacent structures. The pathological findings confirmed that it was langerhans cell histiocytosis(eosinophilic Page 47 of 67

48 granuloma). Isolated involvement of the petrous apex is not common and a middle ear or mastoid location is more typical Fig. 10: Langerhans cell histiocytosis. 8 year old child with headache. The CT scan (Fig 1, Fig 2) shows litic lesion smooth margin that comes from the petrous apex and extends to the medial side of the pyramid, and invades the carotid canal. Axial FSE T2 fat saturated MRi (Fig 3), coronal SET1 (Fig 4) and axial SET1 fat sat with paramagnetic contrast (Fig 5), confirms that it is a vascularized solid lesion invades adjacent structures. Page 48 of 67

49 The pathological findings confirmed that it was langerhans cell histiocytosis(eosinophilic granuloma). Isolated involvement of the petrous apex is not common and a middle ear or mastoid location is more typical Fig. 11: Langerhans cell histiocytosis. 8 year old child with headache. The CT scan (Fig 1, Fig 2) shows litic lesion smooth margin that comes from the petrous apex and extends to the medial side of the pyramid, and invades the carotid canal. Axial FSE T2 fat saturated MRi (Fig 3), coronal SET1 (Fig 4) and axial SET1 fat sat with paramagnetic contrast (Fig 5), confirms that it is a vascularized solid lesion invades adjacent structures. The pathological findings confirmed that it was langerhans cell histiocytosis(eosinophilic granuloma). Isolated involvement of the petrous apex is not common and a middle ear or mastoid location is more typical Page 49 of 67

50 Fig. 12: Langerhans cell histiocytosis. 8 year old child with headache. The CT scan (Fig 1, Fig 2) shows litic lesion smooth margin that comes from the petrous apex and extends to the medial side of the pyramid, and invades the carotid canal. Axial FSE T2 fat saturated MRi (Fig 3), coronal SET1 (Fig 4) and axial SET1 fat sat with paramagnetic contrast (Fig 5), confirms that it is a vascularized solid lesion invades adjacent structures. The pathological findings confirmed that it was langerhans cell histiocytosis(eosinophilic granuloma). Isolated involvement of the petrous apex is not common and a middle ear or mastoid location is more typical Page 50 of 67

51 Fig. 13: Langerhans cell histiocytosis. 8 year old child with headache. The CT scan (Fig 1, Fig 2) shows litic lesion smooth margin that comes from the petrous apex and extends to the medial side of the pyramid, and invades the carotid canal. Axial FSE T2 fat saturated MRi (Fig 3), coronal SET1 (Fig 4) and axial SET1 fat sat with paramagnetic contrast (Fig 5), confirms that it is a vascularized solid lesion invades adjacent structures. The pathological findings confirmed that it was langerhans cell histiocytosis(eosinophilic granuloma). Isolated involvement of the petrous apex is not common and a middle ear or mastoid location is more typical Page 51 of 67

52 Fig. 14: Cephalocele. A 43-year old man presented with right third and fifth cranial neuropathies. Axial CT scans, bone algorithm ( Fig 2 ) and soft tissue window (Fig 1) reveals a sharply marginated expansile right petrous apex mass ( black arrow). Axial ( Fig 3) T2-weighted FSE and axial SE T1 (Fig 4) MR i confirms that the expansile mass revealed on CT studies is a cyst ( yellow arrows) with CSF signal intensity extending from Meckel s cave into the petrous apex Page 52 of 67

53 Fig. 15: Cephalocele. A 43-year old man presented with right third and fifth cranial neuropathies. Axial CT scans, bone algorithm ( Fig 2 ) and soft tissue window (Fig 1) reveals a sharply marginated expansile right petrous apex mass ( black arrow). Axial ( Fig 3) T2-weighted FSE and axial SE T1 (Fig 4) MR i confirms that the expansile mass revealed on CT studies is a cyst ( yellow arrows) with CSF signal intensity extending from Meckel s cave into the petrous apex Page 53 of 67

54 Fig. 16: Cephalocele. A 43-year old man presented with right third and fifth cranial neuropathies. Axial CT scans, bone algorithm ( Fig 2 ) and soft tissue window (Fig 1) reveals a sharply marginated expansile right petrous apex mass ( black arrow). Axial ( Fig 3) T2-weighted FSE and axial SE T1 (Fig 4) MR i confirms that the expansile mass revealed on CT studies is a cyst ( yellow arrows) with CSF signal intensity extending from Meckel s cave into the petrous apex Page 54 of 67

55 Fig. 17: Cephalocele. A 43-year old man presented with right third and fifth cranial neuropathies. Axial CT scans, bone algorithm ( Fig 2 ) and soft tissue window (Fig 1) reveals a sharply marginated expansile right petrous apex mass ( black arrow). Axial ( Fig 3) T2-weighted FSE and axial SE T1 (Fig 4) MR i confirms that the expansile mass revealed on CT studies is a cyst ( yellow arrows) with CSF signal intensity extending from Meckel s cave into the petrous apex Page 55 of 67

56 Fig. 18: Bilateral Cephalocele. MR image shows a bilateral cyst of CSF signal intensity extending inferiorly into the petrous apex from Meckel s cave ( Fig 2). Axial CT scan ( Fig 1 ) shows bilateral expansile lesion with smooth margins being higher on the right Page 56 of 67

57 Fig. 19: Bilateral Cephalocele. MR image shows a bilateral cyst of CSF signal intensity extending inferiorly into the petrous apex from Meckel s cave ( Fig 2). Axial CT scan ( Fig 1 ) shows bilateral expansile lesion with smooth margins being higher on the right Page 57 of 67

58 Fig. 20: Cholesteatoma. CT with bone window into a woman of 43 years with hearing loss of conduction. It shows a destructive lesion centered in the middle ear and mastoid process progresses to the petrous apex. Surgical excision was performed. Histologic examination confirmed cholesteatoma Page 58 of 67

59 Fig. 21: Cholesterol Granuloma. Male 16 years of age who complains of episodes of visual disturbance and headache underwent conventional MRI and diffusion. There is a hyperintense lesion on T2 FSE and FLAIR sequence (Figures 1 and 2) non-aggressive edge and without enhancement. In the study of diffusion (fig 3) was not hyperintense, which ruled out that it is a cyst epidermide. The diagnostco to think, as a first possibility is a cholesterol granuloma Page 59 of 67

60 Fig. 22: Cholesterol granuloma. Male 16 years of age who complains of episodes of visual disturbance and headache underwent conventional MRI and diffusion. There is a hyperintense lesion on T2 FSE and FLAIR sequence (Figures 1 and 2) non-aggressive edge and without enhancement. In the study of diffusion (fig 3) was not hyperintense, which ruled out that it is a cyst epidermide. The diagnostco to think, as a first possibility is a cholesterol granuloma Page 60 of 67

61 Fig. 23: Cholesterol granuloma. Male 16 years of age who complains of episodes of visual disturbance and headache underwent conventional MRI and diffusion. There is a hyperintense lesion on T2 FSE and FLAIR sequence (Figures 1 and 2) non-aggressive edge and without enhancement. In the study of diffusion (fig 3) was not hyperintense, which ruled out that it is a cyst epidermide. The diagnostco to think, as a first possibility is a cholesterol granuloma Page 61 of 67

62 Fig. 24: Meningioma, whose wide base of implantation is on the medial edge of the pyramid which forms the petrous apex. The lesion shows a calcified meningeal thickening (Fig. 1), filling the tank side to the pons, demonstrating diffuse enhancement typical of meningiomas (due to its vascularization), in TC (fig2) and MR (fig3) Page 62 of 67

63 Fig. 25: Meningioma, whose wide base of implantation is on the medial edge of the pyramid which forms the petrous apex. The lesion shows a calcified meningeal thickening (Fig. 1), filling the tank side to the pons, demonstrating diffuse enhancement typical of meningiomas (due to its vascularization), in TC (fig2) and MR (fig3) Page 63 of 67

64 Fig. 26: Meningioma, whose wide base of implantation is on the medial edge of the pyramid which forms the petrous apex. The lesion shows a calcified meningeal thickening (Fig. 1), filling the tank side to the pons, demonstrating diffuse enhancement typical of meningiomas (due to its vascularization), in TC (fig2) and MR (fig3) Page 64 of 67

65 Conclusion Know the different types of lesions that appear on petrous apex is crucial because there are a large number of injuries that should not be touched. The radiographic appearance on CT and MRI can approach a narrow differential diagnosis, which is essential to make a treatment decision. If the image gives a series of malignant and aggressive aspects always requires histological diagnosis and/or surgery, but there are a few lesions or variants that are incidental findings, which only require inspection by imaging methods Personal Information Ignacio Alba de Cáceres, UCR, Unidad Central de Radiodiagnostico, Hospital Infanta Sofía, Madrid, Spain References Br J Radiol May;81(965): Epub 2008 Jan 21. Imaging of the petrous apex: a pictorial review. Connor SE, Leung R, Natas S. Otolaryngol Clin North Am Jun;40(3): , viii. Lesions of the petrous apex: diagnosis and management. Isaacson B, Kutz JW, Roland PS. Page 65 of 67

66 Am J Otol Mar;19(2): Petrous apex lesions. Muckle RP, De la Cruz A, Lo WM. Am J Otol Nov;12(6): Differential diagnosis of primary petrous apex lesions. Arriaga MA, Brackmann DE. Cholesterol granuloma of the petrous apex] [Article in Spanish] Morales Angulo C, del Valle Zapico A, Paternina G, Diéz Lizuain ML, González Rodilla I, Rama Quintela J. Servicio de ORL, Hospital Universitario Marqués de Valdecilla, Santander. Ann Otolaryngol Chir Cervicofac Sep 25. [Epub ahead of print] [Petrous apex lesions.] [Article in French] Karkas A, Righini CA, Spinato L, Lefournier V, Schmerber S. Clinique universitaire oto-rhino-laryngologie, CHU A.-Michallon, BP 217, Grenoble cedex 09, France. Neuroimaging Clin N Am Aug;19(3): Petrous apex. Schmalfuss IM. Department of Radiology, Malcolm Randall VA Medical Center, Gainesville, FL 32608, USA. Page 66 of 67

67 Page 67 of 67