skull base imaging
TRANSCRIPT
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IMAGING OF SKULL BASEIMAGING OF SKULL BASE
--Dr.A.Joseph Stalin(MCh PG)Dr.A.Joseph Stalin(MCh PG)
PROF .R.R UNIT
DEPT OF SURGICAL ONCOLOGY
GOVT ROYAPETTAH HOSPITAL
CHENNAI
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CONTENTSCONTENTS
1.REVIEW OF ANATOMY2.ROLE OF IMAGING3.IMPORTANT PATHOLOGICAL
LEISIONS IN IMAGING4.CLINICAL EXAMPLES
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Cranial fossaCranial fossa
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Skull Base Anatomy Review
Temporal Bone
Temporal bone- petrous portion
Sphenoid Bone
Occipital Bone
Key Fissures
• Petrosphenoidal fissure
• Petrooccipital fissure
Key Sutures
• Sphenosquamous Suture
• Occipitomastoid Suture
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Skull Base Anatomy Review
Key Openings
• Foramen spinosum
• Foramen ovale
• Foramen lacerum
• Foramen rotundum
• Foramen magnum
• Foramen of vesalius
• Jugular foramen
• Superior orbital fissure
• Inferior orbital fissure
• Optic canal
• Vidian canal
• Hypoglossal canal
• Pterygopalatine fossa
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Skull Base Anatomy Review
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Skull Base Anatomy Review
Foramen spinosum
Sphenoid spine- lower level
Foramen rotundum- higher level
Pterygopalatine fossa
Foramen ovale
Petro-occipital fissure
Pterygoid canal
f. lacerum
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ModalityModalityCT
CTA
SPECT
ABOX-CT
MRI
MR SPECTROSCOPY
PET CT
DSA
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ROLE OF IMAGINGROLE OF IMAGING
Diagnosis Deciding Resectability Planning of Treatment- Approach
Specialist Help
Reconstruction Follow up/Recurrance
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DiagnosisDiagnosis
Site ExtendConsistencyVascularityBony InvolvementPerineural spreadVascular Involvement
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Characterisation of the lesionCharacterisation of the lesion
Morphology 1. tissue characterisation 2. pattern of bone involvment 3. vascularity Localisation 1. intrinsic to the skull base 2. arising from intracranial compartment 3. arising from extracranial head and neck Invasion of other structures 1. Direct extension
• infiltrating bone, soft tissue, meninges, cerebrum• preformed channels and foramina
2. Hematogenous spread 3. Perineural spread
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Agressive bone involvement patternAgressive bone involvement pattern
Osteolysis Absent bone replaced by soft tissue Thinned bone with soft tissue mass on
its both sides Abnormal signal of the bone marrow Calcifications within the soft tissue mass
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Non-aggressive bone involvement patternNon-aggressive bone involvement pattern Bone remodeling with bowing, thin or demineralized walls Bone expansion with smooth contour or interrupted walls Enlarged intramedullary cavity Varying attenuation: ground-glass, radiolucent or sclerotic
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INTRACRANIAL <> EXTRA CRANIALINTRACRANIAL <> EXTRA CRANIAL
Pharygeal mucosal space PMS Sinus Morgagni Parapharyngeal space PPS Skull base Carotid space CS Carotid canal Jugular foramen Mandibular space MS Foramen ovale Retropharyngeal space RPS Basiocciput
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Sinus frontalis Squamous Cell Sinus frontalis Squamous Cell Cancer with intracranial Cancer with intracranial
spread spread
Nodular dural enhancing have high specificity
Dural thickness > 5 mm Coexistent leptomeningeal
enhancement Hypointense leision Brain parenchymal changes
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Perineural spreadPerineural spread
Nerve enlargement and nerve enhancement Obliteration of the fat in the foramina, fosse or fissures Foraminal enlargement or destruction Enhancing soft tissue in the cavernous sinus and Meckel cave Neuropathic atrophy and fat replacement
Tumor growth Tumor growth
Incresed permeability of endoneurial capillariesIncresed permeability of endoneurial capillaries
Rupture of the blood-nerve barrierRupture of the blood-nerve barrier
Contrast-enhancementContrast-enhancement
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Dural, PeriNeuralSpreadDural, PeriNeuralSpread
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Ethmoidal Adenocarcinoma with Ethmoidal Adenocarcinoma with perineural spread in pterigopalatine fossaperineural spread in pterigopalatine fossa
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Cavernous sinus infiltrationCavernous sinus infiltration
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Internal carotid artery Internal carotid artery encasementencasement
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ABOX CTABOX CT
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ABOX-CTABOX-CT
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Imaging ChecklistImaging Checklist
Bony involvement- site/extensionScan all FORAMINA- content involvementSA plane/Dural/Brain involvementCarotid Sinus/other sinusesInternal Carotid Artery course/encasementPerineural spread
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CRITERIA FOR NON CRITERIA FOR NON RESECTABILITY RESECTABILITY
Cavernous sinus infiltration
B/l optic nerve/optic chiasmal infiltration
Sphenoid sinus infiltration (superior/lateral )
Extensive brain involvement- temporal lobe for anterior resection
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Skull Base Pathology
Chordoma
Chondrosarcoma
Dermoid tumors
Epidermoid tumors
Glomus tumors
Meningioma
Metastases
Myeloma
Neuroma
Schwannoma
Vascular Aneurysm
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ANTERIOR SKULL BASEANTERIOR SKULL BASE
MENINGIOMA
SINONASAL MALIGNANCY
OLFACTORY NEUROBLASTOMA
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MIDDLE SKULL BASEMIDDLE SKULL BASE
Pituitary adenomaCraniopharyngiomaSphenoid sinus malignancySchwanoma
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POSTERIOR SKULL BASEPOSTERIOR SKULL BASE
ChordomaAcoustic neuromaChondrosarcomaParaganglioma
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SINONASAL MALIGNANCYSINONASAL MALIGNANCY
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Bony invasionBony invasion
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Bone marrow spaceBone marrow space
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Pterygopalatinefossa Pterygopalatinefossa infiltrationinfiltration
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orbitorbit
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Occular muscleOccular muscle
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Normal ethamoid sinusNormal ethamoid sinus
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Ethamoid tumourEthamoid tumour
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EsthenioneuroblastomaEsthenioneuroblastoma
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Anterior cranial fossa tumour Anterior cranial fossa tumour with dural involvementwith dural involvement
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CarotidvesselsCarotidvessels
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Encased carotidEncased carotid
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Cavernous sinus infiltrationCavernous sinus infiltration
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Perinueral spreadPerinueral spread
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Case 1
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Chondrosarcoma
CT Findings:
• Irregular, destructive mass
• Centered off midline
• Petro-occipital fissure
• Calcifications, 70%; “rings/arcs”
MRI Findings:
• Low T1 signal, high T2 signal
• Enhance with contrast
• Scalloped, well circumsribed margins
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ChondrosarcomaOrigin:
• Preexisting cartilaginous lesion, synchondroses, cartilage endplates
Location:
• Paranasal sinuses, skull base, parasellar region
• Long bones, pelvis, sternum, ribs
Clinical:
• 45 yo, median age
• Classic, mesenchymal, or dedifferentiated
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Case 2
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CT/MRI Findings:
• Expansile lytic lesion, midline
• Well delineated mass arising from bone
• Large soft tissue component
• Variable calcification
• Anteroposterior extension
• Heterogeneous enhancement on T1, T2
• Dark on T1, bright on T2
Chordoma
Differential Diagnosis:
• Chondroma
• Chondrosarcoma
• Clivus meningioma
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ChordomaOrigin
• Notochord remnants
Location
• Clivus 35%
• Sacrum 50%, Vertebral bodies 15%
Clinical
• age 30-70
• Slow growing, locally aggressive
• CN VI- CN deficits
• Mets late
• Tx: surgery, radiation
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Case 3
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Glomus Tumor
Glomus jugulare CT/MRI Findings:
• Center: jugular foramen
• Limit: hyoid bone
• Enhance w/ contrast
• Salt and pepper appearance on MRI
• Bone erosion
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Glomus Tumor
Origin:
• Chemoreceptor cells
Location:
• 10% multiple
• glomus jugulare: jugular bulb
• glomus tympanicum: cochlear promontory
Clinical:
• Pulsatile tinnitus
• Hearing loss
• arrythmia, BP fluctuation
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CONCLUSIONCONCLUSION
Thorough anatomical knowledge essential.Both CT and MRI are needed. Histological diagnosis not needed for
managing skull base tumours.Main role of imaging is to plan the
recection .Treatment options for skull base tumours –
resection +/_ radiotherapy
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CONCLUSIONCONCLUSION
Anatomy of skull base – complex – not the imaging
Treatment options –simple- not the procedure
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Thank u….Thank u….