Epicentre of the Skull Base: Multi-Modality Imaging and Approach to Clival Lesions

Transcription

1 Epicentre of the Skull Base: Multi-Modality Imaging and Approach to Clival Lesions Poster No.: C-1919 Congress: ECR 2014 Type: Educational Exhibit Authors: M. Zhang, J. R. Nair, J. J. R. Chong, J. Chankowsky, C. Torres, R. del Carpio; Montreal, QC/CA Keywords: Neoplasia, Inflammation, Congenital, Education, MR, CT, Neuroradiology brain, Musculoskeletal system DOI: /ecr2014/C-1919 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 42

2 Learning objectives The purpose of this educational exhibit is to: 1) Review the anatomy and embryological development of the clivus and craniometry of the cranio-vertebral junction. 2) Illustrate a systematic approach to the differential diagnosis of clival lesions. 3) Review common and uncommon clival lesions with emphasis on CT and MRI imaging findings. Background ANATOMY The clivus is a sloping bony structure in the skull base bounded [1] (Fig. 1 on page 7): Anteriorly by the sella turcica Posteriorly by the foramen magnum Laterally by the petro-occipital fissures separating it from the petrous portion of the temporal bones. Given its intimate relationship with the brainstem, any pathology of clivus can have potential devastating consequences. Page 2 of 42

3 Fig. 1: CT sagittal and axial views (bone algorithm) (a) The clivus is bound anteriorly by (1) the sella turcica and posteriorly by (2) foramen magnum. (b) The clivus is bound laterally by (3) petro-occipital fissures. References: McGill University Health Centre - Montreal/CA CRANIO-VERTEBRAL JUNCTION The clivus is an important landmark for the cranio-vertebral junction and an integral part of the craniometry for assessment of cranio-vertebral junction abnormalities [1, 2]: Commonly used lines and angle are: McRae line (Fig. 2 on page 7) Boogaard angle (Fig. 3 on page 8) Wackenheim clivus line (Fig. 4 on page 9). Page 3 of 42

4 Fig. 2: McRae line. It is drawn across the foramen magnum opening from the anterior margin (basion) to the posterior margin (opisthion). The tip of the odontoid normally should lie below this line. References: McGill University Health Centre - Montreal/CA Page 4 of 42

5 Fig. 3: Boogaard angle. It measures between the McRae line and the sella-to-basion line (i.e. clivus plane). This angle should measure degrees. Increased angle is suggestive of platybasia. References: McGill University Health Centre - Montreal/CA Page 5 of 42

6 Fig. 4: Wackenheim clivus line. It is drawn along the clival slope. Its extrapolation inferiorly should fall tangential to the odontoid process tip at its posterior aspect. References: McGill University Health Centre - Montreal/CA EMBRYOLOGY 4 elements of the first somites of the axial sclerotomes are integrated to form the embryological skull base [1]. The notochord is an important developmental element, as it perforates the primitive skull base to lie at the ventral aspect of the future clivus. The notochord material diminishes in size during maturation but some islands of notochord may persist within the clivus and its proliferation later on could cause entities such as physaliphora and chordomas. Hypochordal blastemas, which lie in front of the future vertebral bodies, constitute another embryological element that affects the clivus. If they are not reabsorbed, as they should with embryological development, the persistent portions could cause clival osseous variations such as a third condyle, prominent basilar processes or pre-basio-occipital arch. Page 6 of 42

7 NORMAL IMAGING FINDINGS In the adult, the normal clivus has characteristic imaging findings [3]: T1W images: The clivus gradually transforms from uniformly low signal on T1 to high signal with advancing age, due to conversion of red to yellow marrow. A uniformly T1 low signal of the clivus relative to the pons should be considered abnormal in an adult. T2W images: The adult clivus is usually isointense relative to the pons, but a small portion may be hyper or isointense. T2W images are particularly useful to detect tumor invasion when the lesion itself is hyperintense. Gadolinium: The normal clivus can have mild non-pathological enhancement. Images for this section: Fig. 1: CT sagittal and axial views (bone algorithm) (a) The clivus is bound anteriorly by (1) the sella turcica and posteriorly by (2) foramen magnum. (b) The clivus is bound laterally by (3) petro-occipital fissures. Page 7 of 42

8 Fig. 2: McRae line. It is drawn across the foramen magnum opening from the anterior margin (basion) to the posterior margin (opisthion). The tip of the odontoid normally should lie below this line. Page 8 of 42

9 Fig. 3: Boogaard angle. It measures between the McRae line and the sella-to-basion line (i.e. clivus plane). This angle should measure degrees. Increased angle is suggestive of platybasia. Page 9 of 42

10 Fig. 4: Wackenheim clivus line. It is drawn along the clival slope. Its extrapolation inferiorly should fall tangential to the odontoid process tip at its posterior aspect. Page 10 of 42

11 Findings and procedure details This pictorial review will concentrate on the common and uncommon entities involving the clivus classified by etiological categories: non-neoplastic, neoplastic, inflammatory and traumatic. The differential diagnosis of clival lesions then can be further narrowed down by their locations, depending on whether it arises from the skull base, intracranially or below the skull base [1]. NON-NEOPLASTIC MASSES FIBROUS DYSPLASIA Fibrous dysplasia of the skull is a well-known though rare entity, often confused with neoplastic processes [1, 4]. Its pathophysiology involves replacement of the normal bone marrow with fibrous bone causing expansion and weakening of the bone. It is often asymptomatic and treated conservatively, unless associated with nerve compression or involvement of the condyles, for which surgical management could be considered [4]. There are 3 main forms of fibrous dysplasia on imaging: lytic, sclerotic and mixed, the latter being the least common. The appearance on imaging is usually typical enough to make the diagnosis [4]. CT findings: (Fig. 5 on page 27) Ground glass appearance (seen in all cases of clival fibrous dysplasia) Thinning of cortical bone Bony expansion Rarely with a lytic component MRI findings: (Fig. 5 on page 27) Hypointense on T1W images Hypointense or intermediate signal (higher metabolic activity) on T2W images Variable (mild to strong) gadolinium enhancement Page 11 of 42

12 Differential diagnosis: Paget's disease, giant cell tumors, hemangioma, lymphoma, metastasis, other clival neoplastic lesion Fig. 5: Fibrous dysplasia found incidentally in a 37 year old male patient. (a) Axial CT images show ground glass appearance of the clivus. (b) Sagittal T1 and (c) T2 MR images show hypointense signals on both T1 and T2 in the clivus. References: McGill University Health Centre - Montreal/CA ECCHORDOSIS PHYSALIPHORA Ecchordosis physaliphora is a relatively common incidental finding (up to 2% of autopsies), arising from ectopic notochordal remnant. Histopathologically, it is difficult to distinguish from its more aggressive counterpart, chordomas [1, 5]. Though a benign lesion, it can bleed and cause CSF leakage [6, 7]. Radiologically, ecchordosis physaliphora is a midline structure [1, 5, 8]. Page 12 of 42

13 CT findings: (Fig. 6 on page 28) Limited assessment because of the lesion's small size and posterior fossa artifacts Well demarcated lytic lesions MRI findings: (Fig. 6 on page 28) Hypointense on T1W images Hyperintense on T2W images; in most cases the high T2 signal reach the posterior wall of the clivus No significant gadolinium enhancement in contrast to chordoma Differential diagnosis: Chordoma, epidermoid cyst, metastasis Fig. 6: Ecchordosis physaliphora found incidentally in a 50 year old female posttrauma patient. (a) CT images demonstrate a well circumscribed lytic lesion in the right aspect of the clivus. (b) T1W and (c) T1W post gadolinum images show the clival lesion to have low T1 signal without significant enhancement. (d) T2W images demonstrate the lesion to have hyperintense signal. Page 13 of 42

14 References: McGill University Health Centre - Montreal/CA NEURENTERIC CYST Neurenteric cyst is a developmental lesion secondary to abnormal dysgenesis of notochord or neurenteric canal remnants. Histopathologically, it is similar to Rathke cleft cyst and colloid cysts, but is distinguished depending on its locations [1, 9]. CT findings: Lytic lesion Intact cortex MRI findings: Different MR T1 and T2 signals depending on protein content Low protein content = # T1W and #T2W signals; intermediate protein content = #T1W and #T2W signals; high protein content = #T1W and #T2W signals [10] The main differential for the radiological appearance is a sphenoid sinus mucocele, in addition to the other clival entities [1, 9]. NEOPLASTIC MASSES ARISING FROM THE CLIVUS CHORDOMA Chordomas constitute 1% of intracranial neoplasms [1]. They arise from notochord remnants and are usually slow-growing lesions. With growth it can encase the visual pathways, adjacent vessels and cranial nerves, causing symptoms of headache, visual and cranial nerve disturbances. Surgical removal and radiation therapy are available treatment options, though local recurrence is fairly common [11]. CT findings: (Fig. 7 on page 29) Well-delineated, expansile, centrally located lytic lesion with soft tissue components May contain intratumoral calcification (sequestra from bony destruction) Relatively hyperdense compared to the brain parenchyma Page 14 of 42

15 MRI findings: (Fig. 8 on page 30) Low to intermediate signal on T1W images with possible small foci of intratumoral hyperintensities (hemorrhage or mucus pool) Very high signal on T2W images (due to high fluid content) Moderate to marked gadolinium contrast enhancement; lack of enhancement suggest necrosis / large amount of mucinous content Enhancement may be of "honeycomb" appearance Differential diagnosis: plasmacytoma Chondrosarcoma, metastasis, atypical meningioma, Fig. 7: Chordoma found in a 38 year old male patient who then underwent resection. (a) CT head axial in soft tissue and (b) bone windows demonstrating an expansile lytic lesion in the clivus with soft tissue components and irregular intratumoral calcifications. (c) Sagittal CT head images again demonstrate the clival bony destructive process. References: McGill University Health Centre - Montreal/CA Page 15 of 42

16 Fig. 8: Chordoma (same patient as in figure 7). (a) MR images T1 and (b) post gadolinium contrast images demonstrate the expansile aggressive lesion centered around the clivus to be hypointense on T1 and demonstrates marked enhancement with contrast. (c) The lesion is very hyperintense on T2W images. References: McGill University Health Centre - Montreal/CA CHONDROSARCOMA Clival chondrosarcoma is a malignant neoplasm similar to chordoma. Though histopathologically they can be distinguished from one another, radiological features cannot reliably distinguish the two entities [11, 12]. Clinically, chondrosarcomas respond much better to surgery and proton beam radiation than chordoma and has a relatively more favorable outcome with treatment. CT and MR findings [11, 12]: (Fig. 9 on page 31) CT and MR findings similar to chordoma as described above Page 16 of 42

17 Chordomas tend to be midline in location whereas clival chondosarcomas tend to arise along the petro-occipital fissure Chondrosarcoma intratrumoral calcifications tend to be more linear, globular or arclike Fig. 9: Petroclival chondrosarcoma in a 28 year old female patient who then underwent surgical resection. (a) CT in bone windows demonstrates an expansile lytic bony lesion at the right petroclival region with soft tissue component and intratumoral calcification. As opposed to chordomas which are more midline, chondrosarcomas tend to arise along the petro-occiptal fissure. But otherwise, its appearance is very similar to that of chordoma. (b) MRI T1 and (c) T1 post gadolinium images demonstrate the lesion to be hypointense on T1 with marked enhancement post contrast. (d) T2W images demonstrate the lesion to be hyperintense. References: McGill University Health Centre - Montreal/CA METASTASIS Page 17 of 42

18 Clival metastases are rare and are usually caused by hematogenous spread. Headache and diplopia (from sixth cranial nerve involvement) are the most common symptoms [3, 13]. Prostate cancer in male and breast cancer in female are the most common primaries. Unfortunately, even with treatment / decompression, symptoms rarely improve and the prognosis is very poor. CT and MR findings [13]: (Fig. 10 on page 32) There are no radiological distinguishing features of metastases and the diagnosis is made with help of clinical history and histopathology. Metastases tend to be more hypointense on T2W images (higher cellularity) compared with chondromas and chondrosarcomas. The differential is broad as it can mimic almost any clival lesion. Fig. 10: Prostate clival metastasis in a 62 year old male patient with known prostate cancer with extensive bony involvement confirmed by bone scan. (a) Sclerotic expansile appearance of the clivus. (b) On MR T1W image, the clivus is expanded and abnormally hypointense. The adult clivus, especially in a patient of this age, should be Page 18 of 42

19 hyperintense on T1. (c) Post gadolinium, there is mild enhancement of the clivus. (d) On T2W images, the abnormal clivus is hyperintense. References: McGill University Health Centre - Montreal/CA LYMPHOMA Lymphoma, plasmacytoma and multiple myeloma may also rarely involve the clivus [14]. Their radiological findings are similar to the disease process found elsewhere in the body (Fig. 11 on page 33). Fig. 11: Multiple myeloma involving the clivus in a 57 year old female found during staging work up. (a) CT shows a lytic lesion in the right aspect of the clivus. (b) MRI T1W and (c) post gadolinium images demonstrates a T1 isointense lesion with homogeneous enhancement. (d) T2W images demonstrate the lesion to be slightly hyperintense but not as much as chordoma or chondrosarcoma. References: McGill University Health Centre - Montreal/CA Page 19 of 42

20 NEOPLASTIC PROCESSES FROM ADJOINING COMPARTMENTS INVASIVE PITUITARY MACROADENOMA Most pituitary adenomas are generally slow growing benign neoplasms, arising from the pituitary fossa but usually confined to the sella or suprasellar cistern [15, 16]. Long-standing and aggressive adenomas can extend posteriorly and inferiorly into the sphenoid sinus / skull base or can encase the cavernous sinuses laterally. CT findings: (Fig. 12 on page 34) Expanded sella Moderately inhomogeneously enhancing soft-tissue mass Dehiscence of surrounding bony structures MRI findings: (Fig. 12 on page 34) Sellar-infrasellar mass lesion isointense to grey matter on T1W images Heterogeneous with possible cystic necrosis on T2W images Intense but heterogeneous post-contrast enhancement No normal pituitary gland identifiable Differential diagnosis: Clival chordoma, sphenoid sinus carcinoma, plasmacytoma or superior extension of nasopharyngeal carcinoma Page 20 of 42

21 Fig. 12: Invasive macroadenoma in a 61 year old female with known sellar lesion. a) CT sagittal and coronal (soft tissue) and (b) CT sagittal (bone algorithm) images reveal soft tissue lesion involving the sella and sphenoid body with extension to the clivus. Bony remodelling and lytic changes noted in the right petrous apex and the clivus. (c) MR T1W images demonstrate hypointense soft tissue mass lesion in the right sella extending inferiorly into the sphenoid sinus with bony destruction, loss of normal marrow signal of the clivus and right petrous apex. On (d) T2W images, the soft tissue shows intermediate signal with mild heterogeneous enhancement on (e) postcontrast images. References: McGill University Health Centre - Montreal/CA INVASIVE NASOPHARYNGEAL CARCINOMA Squamous cell carcinoma is the most common nasopharyngeal tumor of the skull base [15]. Clival invasion from nasopharyngeal cancer (NPC) constitutes stage T3 disease. CT findings: (Fig. 13 on page 35) Mildly enhancing mass lesion arising from the nasopharynx Destruction of posterior skull base and clivus MRI findings: (Fig. 13 on page 35) Hypo to isointense to skeletal muscles on T1W images Page 21 of 42

22 Mildly hyperintense on T2W images (but hypointense as compared to benign mucosal thickening) Mild post-contrast enhancement Bone narrow replacement by lower signal intensity tumor on T1W images with obliteration of normal fat at the skull base Differential diagnosis: Metastasis, lymphoma, primary bone neoplasms can cause skull base destruction with associated soft-tissue mass in the nasopharynx Fig. 13: NPC invasion of the clivus in a 63 year old male with recurrent bilateral otitis media and right-sided facial nerve palsy. (a) CT (soft tissue) and (b) CT (bone algorithm) images reveal large bilateral nasopharyngeal mass lesion causing anterior right clivus bone erosion and destruction of the ethmoid and sphenoid septation. (c) MR T1W images demonstrate bilateral nasopharyngeal mass lesion extending superiorly into the central skull base, with invasion of the sphenoid sinus and clivus but no intracranial extension. (d) On T2W images, the soft tissue appears heterogeneously hyperintense with moderate enhancement on (e) post-contrast images. References: McGill University Health Centre - Montreal/CA INFLAMMATORY LESIONS INFLAMMATORY PSEUDO-TUMOR Page 22 of 42

23 Inflammatory pseudo-tumour (IPT) is an idiopathic inflammatory lesion characterised by the proliferation of myofibroblastic spindle cells [17]. IPT of the nasopharynx and the skull base rarely involves the clivus, but these locally aggressive growths with bony erosions may cause cranial neuropathy. Clinically and radiographically, IPT is indistinguishable from invasive neoplasms. CT findings: (Fig. 14 on page 36) Mildly enhancing nasopharyngeal soft tissue mass lesion with destruction of the clivus May be associated with luminal compromise of the internal carotid artery MRI findings: (Fig. 14 on page 36) Intermediate signal intensity mass lesion involving the nasopharyngeal submucosal region on T1W images Hypointense to the brain parenchyma on T2W images Marrow changes of the clivus, petrous apex and possible narrowing of the left internal carotid artery Extensive pachymeningeal thickening and enhancement postgadolinium injection Important points to differentiate IPT from nasopharyngeal carcinoma (NPC) are [17]: Hypointense mass lesion compared to brain parenchyma while NPC are more hyperintense Internal carotid artery encasement and resultant narrowing is a common features of IPT but not NPC Extensive pachymeningeal thickening and enhancement is a feature of IPT not seen in NPC Page 23 of 42

24 Fig. 14: Pseudotumor (proven pathologically) with clival involvement in a 87 year old male with severe unrelenting headache and recent onset left-sided facial numbness and palsy. (a) CT (soft tissue) and (b) CT (bone algorithm) images reveal nasopharyngeal soft tissue predominantly involving the left side, extending across the midline with destruction of the clivus and left carotid canal. Complete opacification of the left mastoid air cells noted. (c) MR T1W images demonstrate hypointense soft tissue mass lesion in the left posterio-lateral aspect of the nasopharynx with irregularity and loss of normal marrow signal of the clivus. (d) On T2W images, the soft tissue appears hypointense (compared to hyperintense signal in NPC) with reduced caliber of the flow void of the left internal carotid artery. References: McGill University Health Centre - Montreal/CA SKULL BASE OSTEOMYELITIS Skull base osteomyelitis may be secondary to sphenoid or petrous apicitis [18]. CT findings: (Fig. 15 on page 39) Permeative lytic bony changes MRI findings: (Fig. 15 on page 39) Heterogeneous hyperintense signal on T2W images Page 24 of 42

25 Heterogeneous enhancement on post-gadolinium images with occasional associated peripherally enhancing soft tissue suggestive of abscess Fig. 15: Osteomyelitis involving the clivus in a 52 year old male, known case of squamous cell carcinoma of the nasopharynx presenting with headache. MR (a) T1W and (b) T2W axial images reveal loss of normal marrow signal of the base of skull including the clivus with associated soft tissue component. Extensive enhancement of the clivus, petrous and dura noted(arrow)on (c) post-contrast images. References: McGill University Health Centre - Montreal/CA RADIATION-INDUCED OSTEONECROSIS Radiation-induced necrosis of the bone or osteoradionecrosis is frequently seen as sequelae to external beam radiotherapy for nasopharyngeal carcinoma, particularly involving the sphenoid floor, body and clivus [19-21]. CT findings: (Fig. 16 on page 37) Extensive bony disruption with loss of marrow trabeculation MRI findings: (Fig. 16 on page 37) Heterogeneous hyperintense signal on T2W images Page 25 of 42

26 Patchy enhancement on post-gadolinium images in the adjacent bone with edema in the adjacent muscles Differential diagnosis: Recurrent nasopharyngeal tumor Fig. 16: 52 year old male, known case of nasopharyngeal cancer post-external beam radiotherapy presents with headache. (a) CT sagittal, (b)(c) and axial images in bone algorithm reveal irregularity and sclerosis of the clivus, petrous apices, body of sphenoid and walls forming the maxillary and ethmoid sinuses. MR T1W (d) axial, (e) coronal and (f) post-contrast images demonstrate loss of normal marrow signal of the clivus and osseous structures of skull base with moderate post-contrast enhancement. References: McGill University Health Centre - Montreal/CA TRAUMA Clival fractures (Fig. 17 on page 38) are rare in both pediatric and adult trauma population with reported incidences ranging from 0.21% to 0.56% of all head injuries [22]. They are often accompanied by other serious cranial or systemic injuries. Clinical outcome is difficult to predict and dependent on the presenting GCS score as well as associated brain parenchymal injury rather than extent of fracture. Page 26 of 42

27 3 major clival fracture types are [22]: 1) Longitudinal fracture located in the basisphenoid; 2) Transverse fracture involving both carotid canals; 3) Oblique-type fracture in the basisphenoid portion of the clival complex. Fig. 17: Clival fracture in a 21 year old male post motor vehicle collision. (a) CT axial, b)sagittal and (d) coronal images in bone algorithm demonstrates an oblique type fracture in the basisphenoid portion of the clival complex. References: McGill University Health Centre - Montreal/CA Images for this section: Page 27 of 42

28 Fig. 5: Fibrous dysplasia found incidentally in a 37 year old male patient. (a) Axial CT images show ground glass appearance of the clivus. (b) Sagittal T1 and (c) T2 MR images show hypointense signals on both T1 and T2 in the clivus. Page 28 of 42

29 Fig. 6: Ecchordosis physaliphora found incidentally in a 50 year old female post-trauma patient. (a) CT images demonstrate a well circumscribed lytic lesion in the right aspect of the clivus. (b) T1W and (c) T1W post gadolinum images show the clival lesion to have low T1 signal without significant enhancement. (d) T2W images demonstrate the lesion to have hyperintense signal. Page 29 of 42

30 Fig. 7: Chordoma found in a 38 year old male patient who then underwent resection. (a) CT head axial in soft tissue and (b) bone windows demonstrating an expansile lytic lesion in the clivus with soft tissue components and irregular intratumoral calcifications. (c) Sagittal CT head images again demonstrate the clival bony destructive process. Page 30 of 42

31 Fig. 8: Chordoma (same patient as in figure 7). (a) MR images T1 and (b) post gadolinium contrast images demonstrate the expansile aggressive lesion centered around the clivus to be hypointense on T1 and demonstrates marked enhancement with contrast. (c) The lesion is very hyperintense on T2W images. Page 31 of 42

32 Fig. 9: Petroclival chondrosarcoma in a 28 year old female patient who then underwent surgical resection. (a) CT in bone windows demonstrates an expansile lytic bony lesion at the right petroclival region with soft tissue component and intratumoral calcification. As opposed to chordomas which are more midline, chondrosarcomas tend to arise along the petro-occiptal fissure. But otherwise, its appearance is very similar to that of chordoma. (b) MRI T1 and (c) T1 post gadolinium images demonstrate the lesion to be hypointense on T1 with marked enhancement post contrast. (d) T2W images demonstrate the lesion to be hyperintense. Page 32 of 42

33 Fig. 10: Prostate clival metastasis in a 62 year old male patient with known prostate cancer with extensive bony involvement confirmed by bone scan. (a) Sclerotic expansile appearance of the clivus. (b) On MR T1W image, the clivus is expanded and abnormally hypointense. The adult clivus, especially in a patient of this age, should be hyperintense on T1. (c) Post gadolinium, there is mild enhancement of the clivus. (d) On T2W images, the abnormal clivus is hyperintense. Page 33 of 42

34 Fig. 11: Multiple myeloma involving the clivus in a 57 year old female found during staging work up. (a) CT shows a lytic lesion in the right aspect of the clivus. (b) MRI T1W and (c) post gadolinium images demonstrates a T1 isointense lesion with homogeneous enhancement. (d) T2W images demonstrate the lesion to be slightly hyperintense but not as much as chordoma or chondrosarcoma. Page 34 of 42

35 Fig. 12: Invasive macroadenoma in a 61 year old female with known sellar lesion. a) CT sagittal and coronal (soft tissue) and (b) CT sagittal (bone algorithm) images reveal soft tissue lesion involving the sella and sphenoid body with extension to the clivus. Bony remodelling and lytic changes noted in the right petrous apex and the clivus. (c) MR T1W images demonstrate hypointense soft tissue mass lesion in the right sella extending inferiorly into the sphenoid sinus with bony destruction, loss of normal marrow signal of the clivus and right petrous apex. On (d) T2W images, the soft tissue shows intermediate signal with mild heterogeneous enhancement on (e) post-contrast images. Page 35 of 42

36 Fig. 13: NPC invasion of the clivus in a 63 year old male with recurrent bilateral otitis media and right-sided facial nerve palsy. (a) CT (soft tissue) and (b) CT (bone algorithm) images reveal large bilateral nasopharyngeal mass lesion causing anterior right clivus bone erosion and destruction of the ethmoid and sphenoid septation. (c) MR T1W images demonstrate bilateral nasopharyngeal mass lesion extending superiorly into the central skull base, with invasion of the sphenoid sinus and clivus but no intracranial extension. (d) On T2W images, the soft tissue appears heterogeneously hyperintense with moderate enhancement on (e) post-contrast images. Page 36 of 42

37 Fig. 14: Pseudotumor (proven pathologically) with clival involvement in a 87 year old male with severe unrelenting headache and recent onset left-sided facial numbness and palsy. (a) CT (soft tissue) and (b) CT (bone algorithm) images reveal nasopharyngeal soft tissue predominantly involving the left side, extending across the midline with destruction of the clivus and left carotid canal. Complete opacification of the left mastoid air cells noted. (c) MR T1W images demonstrate hypointense soft tissue mass lesion in the left posterio-lateral aspect of the nasopharynx with irregularity and loss of normal marrow signal of the clivus. (d) On T2W images, the soft tissue appears hypointense (compared to hyperintense signal in NPC) with reduced caliber of the flow void of the left internal carotid artery. Page 37 of 42

38 Fig. 16: 52 year old male, known case of nasopharyngeal cancer post-external beam radiotherapy presents with headache. (a) CT sagittal, (b)(c) and axial images in bone algorithm reveal irregularity and sclerosis of the clivus, petrous apices, body of sphenoid and walls forming the maxillary and ethmoid sinuses. MR T1W (d) axial, (e) coronal and (f) post-contrast images demonstrate loss of normal marrow signal of the clivus and osseous structures of skull base with moderate post-contrast enhancement. Page 38 of 42

39 Fig. 17: Clival fracture in a 21 year old male post motor vehicle collision. (a) CT axial, b)sagittal and (d) coronal images in bone algorithm demonstrates an oblique type fracture in the basisphenoid portion of the clival complex. Fig. 15: Osteomyelitis involving the clivus in a 52 year old male, known case of squamous cell carcinoma of the nasopharynx presenting with headache. MR (a) T1W and (b) T2W axial images reveal loss of normal marrow signal of the base of skull including the clivus with associated soft tissue component. Extensive enhancement of the clivus, petrous and dura noted(arrow)on (c) post-contrast images. Page 39 of 42

40 Conclusion This pictorial review illustrates the gamut of clival normal variants and pathologies with emphasis on differential diagnosis and lesion characterization. Imaging remains critical for establishing a diagnosis as clinical signs and symptoms are often non-specific or absent. Personal information No disclosures. References 1. Hofmann E, Prescher A. The clivus: anatomy, normal variants and imaging pathology. Clinical neuroradiology. Jun 2012;22(2): Smoker WR. Craniovertebral junction: normal anatomy, craniometry, and congenital anomalies. Radiographics : a review publication of the Radiological Society of North America, Inc. Mar 1994;14(2): Kimura F, Kim KS, Friedman H, Russell EJ, Breit R. MR imaging of the normal and abnormal clivus. AJR. American journal of roentgenology. Dec 1990;155(6): Adada B, Al-Mefty O. Fibrous dysplasia of the clivus. Neurosurgery. Feb 2003;52(2): ; discussion Mehnert F, Beschorner R, Kuker W, Hahn U, Nagele T. Retroclival ecchordosis physaliphora: MR imaging and review of the literature. AJNR. American journal of neuroradiology. Nov-Dec 2004;25(10): Alkan O, Yildirim T, Kizilkilic O, Tan M, Cekinmez M. A case of ecchordosis physaliphora presenting with an intratumoral hemorrhage. Turkish neurosurgery. Jul 2009;19(3): Alli A, Clark M, Mansell NJ. Cerebrospinal fluid rhinorrhea secondary to ecchordosis physaliphora. Skull base : official journal of North American Skull Base Society... [et al.]. Nov 2008;18(6): Nakaji P, van Loveren HR, Agazzi S, Teo C. Clival incidentaloma. Skull base : official journal of North American Skull Base Society... [et al.]. Nov 2006;16(4): Page 40 of 42

41 9. Kapoor V, Johnson DR, Fukui MB, Rothfus WE, Jho HD. Neuroradiologic-pathologic correlation in a neurenteric cyst of the clivus. AJNR. American journal of neuroradiology. Mar 2002;23(3): Hayashi Y, Tachibana O, Muramatsu N, et al. Rathke cleft cyst: MR and biomedical analysis of cyst content. Journal of computer assisted tomography. Jan-Feb 1999;23(1): Erdem E, Angtuaco EC, Van Hemert R, Park JS, Al-Mefty O. Comprehensive review of intracranial chordoma. Radiographics : a review publication of the Radiological Society of North America, Inc. Jul-Aug 2003;23(4): Rosenberg AE, Nielsen GP, Keel SB, et al. Chondrosarcoma of the base of the skull: a clinicopathologic study of 200 cases with emphasis on its distinction from chordoma. The American journal of surgical pathology. Nov 1999;23(11): Pallini R, Sabatino G, Doglietto F, Lauretti L, Fernandez E, Maira G. Clivus metastases: report of seven patients and literature review. Acta neurochirurgica. Apr 2009;151(4): ; discussion Ustuner Z, Basaran M, Kiris T, et al. Skull Base Plasmacytoma in a Patient with Light Chain Myeloma. Skull base : official journal of North American Skull Base Society... [et al.]. Aug 2003;13(3): Ginsberg LE. Neoplastic diseases affecting the central skull base: CT and MR imaging. AJR. American journal of roentgenology. Sep 1992;159(3): Van de Straete S, Githeko J, Demaerel P, et al. Aggressive pituitary macroadenoma: CT and MR appearances. Journal belge de radiologie. Dec 1996;79(6): Lu CH, Yang CY, Wang CP, Yang CC, Liu HM, Chen YF. Imaging of nasopharyngeal inflammatory pseudotumours: differential from nasopharyngeal carcinoma. The British journal of radiology. Jan 2010;83(985): Benoudiba F, Toulgoat F, Sarrazin JL. [Skull base osteomyelitis]. Journal de radiologie. Nov 2011;92(11): Glastonbury CM, Parker EE, Hoang JK. The postradiation neck: evaluating response to treatment and recognizing complications. AJR. American journal of roentgenology. Aug 2010;195(2):W Huang XM, Zheng YQ, Mai HQ, et al. [Diagnosis and treatment on osteoradionecrosis of skull base after radiotherapy for nasopharyngeal carcinoma]. Zhonghua er bi yan hou ke za zhi. Sep 2004;39(9): Page 41 of 42

42 21. Bhatia KS, King AD, Paunipagar BK, et al. MRI findings in patients with severe trismus following radiotherapy for nasopharyngeal carcinoma. European radiology. Nov 2009;19(11): Ochalski PG, Adamo MA, Adelson PD, Okonkwo DO, Pollack IF. Fractures of the clivus and traumatic diastasis of the central skull base in the pediatric population. Journal of neurosurgery. Pediatrics. Mar 2011;7(3): Page 42 of 42