364 lines
32 KiB
Markdown
364 lines
32 KiB
Markdown
---
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title: "Prepontine Cistern Mass"
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docid: "e0f71196-85c7-411c-9c71-e2606b2ee52f"
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authors:
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- key: "26ebc2e8-e4f7-40ee-8f5c-d23fe383e15c"
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value: "Yoshimi Anzai, MD, MPH"
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- key: "83f867a5-a183-4396-82ea-384015da4d2f"
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value: "Gregory L. Katzman, MD, MBA"
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breadcrumbs:
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-
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name: "Head and Neck"
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slug: "head-and-neck"
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treeNodeId: "ed24ed8c-5d57-4629-879b-447b82d2973d"
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-
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name: "Differential Diagnosis"
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slug: "differential-diagnosis"
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treeNodeId: "40d68862-8975-4dde-ac2b-ebc43ab0fb5c"
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-
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name: "CPA-IAC and Posterior Fossa"
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slug: "cpa-iac-and-posterior-fossa"
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treeNodeId: "c590eedb-4a3b-4158-a04f-ad880564c992"
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-
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name: "Anatomically Based Differentials"
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slug: "anatomically-based-differentials"
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treeNodeId: "debfb06c-8656-4f5d-92c1-eaa468185d78"
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-
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name: "Prepontine Cistern Mass"
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slug: "prepontine-cistern-mass"
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treeNodeId: null
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category: "Head and Neck"
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documentVersionId: "8526aadd-9d1f-4f3f-8b6a-cab3c86d8196"
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imageCount: 39
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lastUpdated: "08/02/18"
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pageDescription: "Prepontine Cistern Mass"
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pageKeywords: "Head and Neck, Differential Diagnosis, CPA-IAC and Posterior Fossa, Anatomically Based Differentials, Prepontine Cistern Mass"
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pageTitle: "Prepontine Cistern Mass | STATdx"
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enhancedTitle: "Prepontine Cistern Mass"
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type: "DDX"
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references: true
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breadcrumbs:
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- "Head and Neck"
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- "Differential Diagnosis"
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- "CPA-IAC and Posterior Fossa"
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- "Anatomically Based Differentials"
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- "Prepontine Cistern Mass"
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---
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# ESSENTIAL INFORMATION
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- ## Key Differential Diagnosis Issues
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- Anatomy
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- Extensive CSF space along ventral & lateral pons, dorsal to clivus (a.k.a. pontine cistern)
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- Bounded superiorly by interpeduncular cistern, inferiorly by subarachnoid space of spinal cord, & continuous about medulla with cerebellomedullary cistern
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- Many abnormalities, often from transspatial processes
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- ## Helpful Clues for Common Diagnoses
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- **CSF Flow Artifact**
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- MR artifacts divided into 2 categories: TOF effects & turbulent flow
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- Worsens with thinner slices, longer TE, & imaging perpendicular to flow
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- Assess real vs. artifact in other planes & sequences
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- Minimize TOF losses: Use short TE, image parallel to flow, acquire thicker slices
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- Use 3D sequence in place of 2D
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- Typically most pronounced on axial FLAIR
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- Confirm artifact on T1 & T2 or other planes
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- **Dolichoectasia (Vertebrobasilar)**
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- Older patients
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- Look for ASVD in other vessels
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- Ectasia often extends into branches
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- May have significant mass effect on brainstem & cisternal cranial nerves
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- **Fusiform Aneurysm, ASVD**
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- Long segment fusiform arterial dilatation
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- Involves long nonbranching segments
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- Calcifications common
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- Lumen enhances strongly, clot does not
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- **Meningioma**
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- Clival region dural-based enhancing mass
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- Infratentorial (8-10%): CPA most common
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- Retroclival meningioma
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- Best seen on sagittal T1 C+ FS MR
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- Causes cranial neuropathies or ataxia
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- **Metastases, Skull & Meningeal**
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- Enhancing lesion(s) with skull/meningeal destruction/infiltration
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- Skull involvement causes low marrow signal on T1 MR & enhancement on T1 C+ MR
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- Skull involvement can spread to adjacent dura
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- Metastases may also be dural/meningeal only
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- DWI (mildly ↑ signal) may ↑ conspicuity of calvarial metastases
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- Manifestations: May cause smooth linear thickening or nodular, fungating masses
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- Image entire neuraxis
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- ## Helpful Clues for Less Common Diagnoses
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- **Epidermoid Cyst**
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- Usually extends medially from CPA cistern
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- Lobulated, irregular, insinuating CSF-like mass
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- Doesn't completely suppress on FLAIR; restricts on DWI
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- Cranial nerve involvement not infrequent
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- **Chiari 2 ("Creeping Cerebellum****"****)**
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- Small posterior fossa with low torcular Herophili
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- Cerebellar hemispheres/tonsils herniate anteriorly → "creeping" cerebellum
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- Pons, cranial nerve roots often elongated
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- Fusion & inferior displacement of superior & inferior colliculi: "Tectal beaking"
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- **Exophytic Brainstem Glioma, Pediatric**
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- Nonenhancing mass markedly expanding pons
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- May engulf basilar artery
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- Infiltrative have poor survival
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- Diffuse intrinsic brain stem glioma is now called diffuse midline glioma under 2016 WHO classification; H3, K23M mutant
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- Focal glioma uncommon, better prognosis
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- **Pituitary Macroadenoma (Giant)**
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- No distinct pituitary gland is visible
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- Bone CT variable; may be benign appearing or erosive
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- Heterogeneous contrast enhancement
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- Dural tail may mimic meningioma
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- Typically extends to suprasellar cistern, though occasionally extends posteriorly to prepontine cistern
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- **Neurocysticercosis**
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- Cisterns > parenchyma > ventricles
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- MR best modality; most isointense to CSF
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- Appearance varies depending on stage
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- Basal cistern cysts may be racemose
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- Lobulated cisternal cysts, usually no scolex
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- Cysts variable, typically 5-20 mm with 1-4 mm scolex
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- Scolex is small enhancing soft tissue "dot"
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- Colloidal vesicular stage
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- Result from implantation of cestode *Taenia solium*(pork tapeworm) in human host
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- 3D MR sequences optimize detection
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- **Intracranial Hypotension**
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- Sagittal shows brain descent in 40-50%
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- Pons may be compressed against clivus
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- Diffusely, intensely enhancing dura in 85%
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- Bilateral subdural fluid collections in 15%
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- ## Helpful Clues for Rare Diagnoses
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- **Inflammatory Mass**
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- **Tuberculosis**
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- Basilar meningitis, pulmonary TB
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- Thick basilar exudate ± tuberculomas/abscesses
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- Basilar meningitis may cause infarction due to vascular wall invasion
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- **Fungal diseases**
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- Blastomycosis, coccidiomycosis, histoplasmosis, candidiasis
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- Meningeal enhancement, multiple enhancing brain lesions
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- Frequently ring-enhancing
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- **Neurosarcoid**
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- Classically infiltrates dura, leptomeninges, basal cisterns
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- Solitary or multifocal CNS mass(es) ± abnormal CXR
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- **Clival Neoplasms**
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- **Chordoma, clivus**
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- Destructive midline mass centered in clivus with high T2 signal intensity
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- Sagittal images show tumor "thumb" indenting anterior pons
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- **Chondrosarcoma, skull base**
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- Arises from petrooccipital fissure
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- May extend posteriorly into prepontine cistern
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- Hyperintense on T2, enhances strongly but heterogeneously
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- Chondroid matrix mineralization on CT in 50%
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- **Plasmacytoma, skull base**
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- Solitary intraosseous osteolytic soft tissue mass with nonsclerotic margins
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- Peripherally displaced osseous expansion/fragmentation may be seen
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- **Nasopharyngeal tumor (invading clivus)**
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- Often squamous cell carcinoma arising from nasopharyngeal mucosal space
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- MPR images best show invasion of clivus & prepontine cistern extension
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- **Schwannoma**
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- T2-hyperintense, enhance
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- Larger lesion may be associated with cystic degeneration
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- **Arachnoid Cyst**
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- Extraaxial cyst follows CSF attenuation/signal
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- Suppresses completely with FLAIR; no DWI restriction
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- **Craniopharyngioma**
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- 90% Ca⁺⁺, 90% cystic, 90% enhance
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- May extend behind sella into posterior fossa
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- Location: Anywhere along infundibulum, sellar, suprasellar, & floor of 3rd ventricle
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- Adamantinomatous is most common type (> 90%)
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- May contain T1 hyperintense cyst due to high protein content
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- **Neurenteric Cyst**
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- Round/lobulated nonenhancing mass, slightly hyperintense to CSF on T1, FLAIR
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- Benign malformative endodermal CNS cyst
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- **Ecchordosis Physaliphora**
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- Congenital benign hamartomatous lesion from notochord remnant
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- Extends from clivus into prepontine cistern
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- Hyperintense on T2, no contrast enhancement
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- Bone CT: Well-corticated defect in dorsal clivus
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- Usually asymptomatic, found in 2% of autopsies
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## References
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# Selected References
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1. [Bazan R et al: Clinical symptoms, imaging features and cyst distribution in the cerebrospinal fluid compartments in patients with extraparenchymal neurocysticercosis. PLoS Negl Trop Dis. 10(11):e0005115, 2016](http://www.ncbi.nlm.nih.gov/pubmed/?term=27828966%5Bpmid%5D)
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1. [Louis DN et al: The 2016 World Health Organization Classification of Tumors of the Central Nervous System: a summary. Acta Neuropathol. 131(6):803-20, 2016](http://www.ncbi.nlm.nih.gov/pubmed/?term=27157931%5Bpmid%5D)
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1. [Park HH et al: Ecchordosis physaliphora: typical and atypical radiologic features. Neurosurg Rev. 40(1):87-94, 2016](http://www.ncbi.nlm.nih.gov/pubmed/?term=27206421%5Bpmid%5D)
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1. [Carrillo Mezo R et al: Relevance of 3D magnetic resonance imaging sequences in diagnosing basal subarachnoid neurocysticercosis. Acta Trop. 152:60-65, 2015](http://www.ncbi.nlm.nih.gov/pubmed/?term=26327445%5Bpmid%5D)
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1. [Garcia HH et al: Clinical symptoms, diagnosis, and treatment of neurocysticercosis. Lancet Neurol. 13(12):1202-15, 2014](http://www.ncbi.nlm.nih.gov/pubmed/?term=25453460%5Bpmid%5D)
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1. [Lerner A et al: Imaging of neurocysticercosis. Neuroimaging Clin N Am. 22(4):659-76, 2012](http://www.ncbi.nlm.nih.gov/pubmed/?term=23122261%5Bpmid%5D)
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## Images
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### Selected Images
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**CSF Flow Artifact**
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*Axial FLAIR MR reveals a hyperintense artifact <img src='img/arrows/WS.png'/> due to turbulent flow within the prepontine cistern. This is a common location for flow artifacts. Also note sulcal hyperintensity (not artifact) from subarachnoid hemorrhage <img src='img/arrows/WO.png'/>.*
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**CSF Flow Artifact**
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*Axial FLAIR MR reveals a hyperintense artifact <img src='img/arrows/WS.png'/> due to turbulent flow within the prepontine cistern. This is a common location for flow artifacts. Also note sulcal hyperintensity (not artifact) from subarachnoid hemorrhage <img src='img/arrows/WO.png'/>.*
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**Dolichoectasia (Vertebrobasilar)**
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*Axial T1 C+ MR demonstrates luminal enhancement of a dolichoectatic basilar artery <img src='img/arrows/WS.png'/> with associated deformation of the pons <img src='img/arrows/WO.png'/>.*
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**Fusiform Aneurysm, ASVD**
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*Sagittal T1 MR shows a large mass anterior to the pons and medulla <img src='img/arrows/WS.png'/>. Note mixed hyper-, isointense signal caused by slow flow and laminated clot in this classic ASVD fusiform aneurysm.*
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**Meningioma**
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*Sagittal T1 C+ MR demonstrates avid meningioma enhancement with prepontine cistern extension <img src='img/arrows/WS.png'/> and mass effect on the brainstem. Note the presence of enhancing dural tails <img src='img/arrows/WC.png'/>.*
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**Metastases, Skull & Meningeal**
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*Axial T1 C+ MR demonstrates extensive renal cell metastatic disease involving the clivus and overlying dura <img src='img/arrows/WS.png'/>, effacing the prepontine cistern <img src='img/arrows/WO.png'/>.*
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**Metastases, Skull & Meningeal**
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*Axial T1 C+ MR shows a typical MR case of leptomeningeal seeding of carcinoma along the folia of the cerebellum and the brainstem <img src='img/arrows/WS.png'/> as well as within bilateral Meckel caves <img src='img/arrows/BS.png'/>.*
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**Epidermoid Cyst**
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*Sagittal T1 MR depicts a nearly CSF isointense, nonenhancing, multilobulated epidermoid within prepontine, interpeduncular, & quadrigeminal cisterns <img src='img/arrows/WS.png'/>. Note associated flattening of the ventral pons <img src='img/arrows/WO.png'/>.*
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**Chiari 2 (“Creeping Cerebellum”)**
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*Axial T2 MR shows cerebellar hemispheres herniating or "creeping" <img src='img/arrows/WS.png'/> anteriorly due to a congenitally small posterior fossa of Chiari 2 malformation.*
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**Exophytic Brainstem Glioma, Pediatric**
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*Axial FLAIR MR shows a diffuse brainstem glioma asymmetrically involving the pons <img src='img/arrows/WS.png'/> with a small anterior exophytic component extending into the right prepontine cistern <img src='img/arrows/WC.png'/>, next to the basilar artery <img src='img/arrows/WO.png'/>.*
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**Pituitary Macroadenoma (Giant)**
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*Sagittal T2 MR shows a giant macroadenoma with suprasellar extension <img src='img/arrows/WS.png'/>, invading anteriorly into basisphenoid <img src='img/arrows/WO.png'/>, and posteriorly into the basiocciput <img src='img/arrows/WC.png'/>. The pons and basilar artery are displaced posteriorly and flattened <img src='img/arrows/BS.png'/>.*
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**Neurocysticercosis**
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*Axial T2 MR shows multiple racemose cysts in the subarachnoid spaces including the CPA and quadrigeminal and prepontine cisterns <img src='img/arrows/WS.png'/>. Also note cysts within suprasellar cistern <img src='img/arrows/WO.png'/>.*
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**Intracranial Hypotension**
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*Sagittal T1 C+ MR demonstrates typical findings of intracranial hypotension, with obliteration of the suprasellar and prepontine cisterns <img src='img/arrows/WS.png'/> with a sagging midbrain. Note pontine flattening against the clivus, dural enhancement, and cerebellar tonsillar descent.*
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**Tuberculosis**
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*Axial T1 C+ MR demonstrates typical enhancement and thickened meninges filling the basilar cisterns <img src='img/arrows/WS.png'/> in exudative tuberculous meningitis.*
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**Tuberculosis**
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*Sagittal T1 C+ MR shows tuberculous abscesses within the basal and prepontine cisterns <img src='img/arrows/WS.png'/> as well as within the anterior 3rd ventricle <img src='img/arrows/WO.png'/>.*
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**Fungal Diseases**
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*Axial T1 C+ MR shows thick enhancement in the subarachnoid space and along the pia filling the prepontine cistern <img src='img/arrows/WS.png'/> and extending into the left internal auditory canal <img src='img/arrows/WO.png'/> due to coccidioidal meningitis. Note also thin linear ependymal enhancement lining the 4th ventricle <img src='img/arrows/WC.png'/>.*
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**Fungal Diseases**
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*Axial T1 C+ MR demonstrates fine linear enhancement along the pia <img src='img/arrows/WS.png'/> from candida meningitis.*
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**Neurosarcoid**
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*Sagittal T1 C+ MR demonstrates a typical neurosarcoid appearance and location, with marked multifocal nodular appearing dural-based enhancement <img src='img/arrows/WS.png'/>. The sella, parasellar, and basal cisternal locations are classic.*
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**Chordoma, Clivus**
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*Sagittal T1 C+ MR shows a honeycomb pattern of enhancement with replacement of the clivus <img src='img/arrows/WO.png'/>, "thumbing" of the pons posteriorly <img src='img/arrows/WS.png'/>, and anterior extension of tumor into the sphenoid sinus <img src='img/arrows/WC.png'/>.*
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**Chondrosarcoma, Skull Base**
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*Axial T2 MR reveals hyperintense chondrosarcoma originating from the right petrooccipital fissure, extending posterosuperiorly into Meckel cave, petrous apex, and the prepontine and cerebellopontine angle cisterns <img src='img/arrows/WS.png'/>.*
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**Plasmacytoma, Skull Base**
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*Sagittal T1 MR demonstrates plasmacytoma <img src='img/arrows/WS.png'/> expanding the clivus, invading sphenoid sinus and posterior nasal cavity, and elevating the pituitary gland <img src='img/arrows/WC.png'/>.*
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**Nasopharyngeal Tumor (Invading Clivus)**
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*Sagittal T1 C+ FS MR demonstrates nasopharyngeal squamous cell carcinoma infiltration of the mucosal space <img src='img/arrows/WC.png'/> as well as abnormal marrow signal and cortical destruction of the expanded clivus. Prepontine soft tissue cistern extension is noted posterior to the clivus <img src='img/arrows/WS.png'/>.*
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**Schwannoma**
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*Axial T2 MR shows a partly cystic mass in the left prepontine and cerebellopontine angle cistern <img src='img/arrows/WS.png'/>. The mass displaces and compresses the brainstem. This was a large cystic trigeminal schwannoma.*
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**Arachnoid Cyst**
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*Sagittal T1 MR demonstrates a primarily suprasellar cistern arachnoid cyst <img src='img/arrows/WS.png'/> extending into the interpeduncular <img src='img/arrows/WO.png'/> and prepontine cisterns <img src='img/arrows/WC.png'/>. Note flattening of the ventral pons <img src='img/arrows/BS.png'/>.*
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**Craniopharyngioma**
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*Sagittal T1 C+ MR demonstrates a partially cystic and solid enhancing craniopharyngioma <img src='img/arrows/WC.png'/> in the suprasellar cistern with extension inferior into the prepontine cistern <img src='img/arrows/WS.png'/>.*
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**Neurenteric Cyst**
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*Sagittal T1 MR reveals a well-delineated, slightly ovoid, lobulated mass <img src='img/arrows/WS.png'/> that was hyperintense to cerebrospinal fluid on all sequences.*
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**Ecchordosis Physaliphora**
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*Axial T2 MR shows a lobulated cystic appearing mass in the prepontine cistern that indents the ventral pons <img src='img/arrows/WS.png'/>. The mass is hyperintense relative to CSF. Note subtle dehiscence of clivus <img src='img/arrows/WO.png'/> from where the lesion arose.*
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### Additional Images
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**Fusiform Aneurysm, ASVD**
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*Axial T2WI MR shows a predominately hypointense fusiform aneurysm <img src='img/arrows/WS.png'/>, representing a combination of slow intraluminal flow and subacute mural thrombus.*
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**Epidermoid Cyst**
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*Axial DWI MR shows typical restricted diffusion with an epidermoid cyst <img src='img/arrows/WS.png'/> involving the basal cisterns. Irregular "insinuating" margins as seen here are typical of larger epidermoid cysts, unlike the smooth lobulated borders of arachnoid cysts.*
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**Pituitary Macroadenoma (Giant)**
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*Axial CECT shows a large, lobulated, enhancing, and destructive, skull base mass <img src='img/arrows/WS.png'/> that extends into the anterior, middle, and posterior cranial fossae.*
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**Neurocysticercosis**
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*Sagittal T1WI MR demonstrates a typical case of racemose (grape-like) neurocysticercosis in the basal cisterns <img src='img/arrows/WS.png'/> and 3rd ventricle.*
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**Chordoma, Clivus**
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*Axial T2WI MR shows typical marked T2 hyperintensity <img src='img/arrows/WS.png'/>. Notice how the chordoma displaces the basilar artery towards the right <img src='img/arrows/WC.png'/> and causes "thumbing," or indentation of the ventral pons <img src='img/arrows/WO.png'/>.*
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**Chondrosarcoma, Skull Base**
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*Axial bone CT demonstrates a typical case of a large chondrosarcoma <img src='img/arrows/WS.png'/> involving the right petrooccipital fissure and the greater wing of the sphenoid. Internal matrix calcifications are present.*
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**Plasmacytoma, Skull Base**
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*Axial T2WI MR reveals a plasmacytoma nearly isointense to brain <img src='img/arrows/WS.png'/>. These T2 signal characteristics of this lesion would be unusual for a chordoma or chondrosarcoma.*
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**Nasopharyngeal Tumor (Invading Clivus)**
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*Axial T1 C+ MR shows extensive clival invasion, perineural extension into the left petrous apex and Meckel cave <img src='img/arrows/WS.png'/>, as well as invasion and widening of the left pterygopalatine fossa <img src='img/arrows/WC.png'/>.*
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**Schwannoma**
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*Axial T1 C+ FS MR shows a typical, isolated, intracranial, trigeminal schwannoma bridging the prepontine cistern and Meckel cave affecting the preganglionic segment of the trigeminal nerve <img src='img/arrows/WO.png'/>.*
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**Arachnoid Cyst**
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*Axial T2WI MR demonstrates a primarily suprasellar cistern arachnoid cyst <img src='img/arrows/WS.png'/> extending into the interpeduncular and prepontine cisterns. Note flattening of the pons <img src='img/arrows/WO.png'/>.*
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**Craniopharyngioma**
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*Axial NECT shows the classic findings of craniopharyngioma including a cystic suprasellar mass with rim and globular calcifications <img src='img/arrows/WS.png'/> and fluid-fluid levels <img src='img/arrows/WO.png'/>.*
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**Craniopharyngioma**
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*Sagittal T1WI MR demonstrates hyperintense mass in prepontine cistern <img src='img/arrows/BS.png'/> that is connected to suprasellar mass <img src='img/arrows/BO.png'/> by a thin stalk <img src='img/arrows/BC.png'/>. Craniopharyngioma was found at surgery. Predominance of tumor mass in posterior fossa is unusual.*
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**Neurenteric Cyst**
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*Sagittal T1WI MR shows a large, well-delineated, extraaxial mass <img src='img/arrows/WS.png'/> elevating and displacing the pons and medulla. Note that the cyst internal signal intensity is slightly brighter than cerebrospinal fluid.*
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