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Skull base imaging

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Skull base imaging

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Skull base imaging

  1. 1. Skull Base Imaging 24-5-2016 9.21 pm
  2. 2. Great teachers – All this is their work . I am just the reader of their books .Prof. Paolo castelnuovo Prof. Aldo Stamm Prof. Mario Sanna Prof. Magnan
  3. 3. For Other powerpoint presentatioins of “ Skull base 360° ” I will update continuosly with date tag at the end as I am getting more & more information click www.skullbase360.in - you have to login to slideshare.net with Facebook account after clicking www.skullbase360.in
  4. 4. Dr.Prahlad sir https://www.facebook.com/prahlada?fref=ts skull base imaging lecture Click link for skull base imaging video = https://www.youtube.com/watch? v=HYYB-8pv7k4&feature=youtu.be
  5. 5. Popular videos of skull base imaging in youtube https://www.youtube.com/playlist? list=PLxfT3LHUjLuJD3JsWQU4vL h4X5f_5OD0g
  6. 6. • In book of Mario sanna – “Microsurgery of paragangliomas” given – “ Radiological Anatomy ” in 3rd chapter – click https://books.google.co.in/books? id=7k_jwKyT6d0C&lpg=PP1&dq=mario %20sanna %20paraganglioma&pg=PP101#v=snip pet&q=Radiological %20Anatomy&f=false
  7. 7. Content • Normal skull base anatomy • Pathology intrinsic to skull base – some case examples • Pathology affecting skull base from below – some case examples • A few hints and tips!
  8. 8. Anatomy Five Bones: • Ethmoid - CP • Sphenoid- GW+LW • Occipital • Temporal- paired • Frontal-paired
  9. 9. Cranial Fossae • Anterior • Middle • Posterior
  10. 10. Anterior Cranial Fossa • Anterior • Frontal bone: frontal sinus,supra-orbital foramen • Posterior • Post. edge of lesser wing sphenoid and its ant. Clinoid processes – Intracranial landmarks: foramen ceacum, crista galli, cribiform plate, planum sphenoidal – Extracranial landmarks: nasal cavity, ethmoid and sphenoid sinuses, orbits
  11. 11. Middle Cranial Fossa • Anterior • Posterior edge of lesser wing of sphenoid • Posterior • Post-sup edge of petrous temporal bone
  12. 12. Posterior Cranial Fossa • Anteriorly – Post-sup edge of petrous temporal bone • Posteriorly – it is enclosed by the occipital bone. • Laterally – portions of the squamous temporal and mastoid part of the temporal bone form its walls. • It contains the brainstem and cerebellum.
  13. 13. Skull Base Anatomy Temporal Bone Temporal bone- petrous portion Sphenoid Bone Occipital Bone Key Fissures • Petro-sphenoidal fissure • Petro-occipital fissure Key Sutures • Sphenosquamous Suture • Occipitomastoid Suture
  14. 14. Skull base foramina
  15. 15. FORAMEN OVALE FORAMEN SPINOSUM
  16. 16. CAROTID CANAL JUGULAR FORAMEN
  17. 17. IAC INTERNAL AUDITORY CANAL CAROTID CANAL OSSICLES MALLEUS INCUS
  18. 18. Skull Base Anatomy
  19. 19. Skull Base Anatomy Foramen spinosum Sphenoid spine- lower level Foramen rotundum- higher level Pterygopalatine fossa Foramen ovale Petro-occipital fissure Pterygoid canal f. lacerum
  20. 20. Skull Base Anatomy Foramen Spinosum • Middle meningeal artery/vein • CV V3, recurrent branch • Lesser superficial petrosal nerve Foramen Ovale • CN V3 • Lesser petrosal nerve • Accessory meningeal artery • Emissary veins
  21. 21. Skull Base Anatomy Foramen Lacerum • Ascending pharyngeal artery- meningeal branch • Nerve of pterygoid canal Vidian Canal • aka pterygoid canal • Pterygopalatine fossa - foramen lacerum • Vidian nerve • Vidian artery
  22. 22. Skull Base Anatomy Foramen rotundum • CN V2 • Artery of foramen rotundum • Emissary veins
  23. 23. * Skull Base Anatomy Foramen magnum • Medulla oblongata • Vertebral arteries • Anterior/Posterior spinal arteries Hypoglossal canal • CN XII • Hypoglossal artery *
  24. 24. Skull Base Anatomy Jugular Foramen • Pars nervosa: CN IX, inferior petrosal sinus • Pars vascularis: CN X, XI, jugular bulb * * Carotid canal
  25. 25. Skull Base Anatomy Pterygopalatine Fossa • Pterygopalatine ganglia V2 • Pterygopalatine plexus • Communicates with: Inferior orbital fissure Orbital apex Sphenopalatine foramen Pterygomaxilary fissure Foramen rotundum Vidian canal Greater/lesser palatine canals and foramina
  26. 26. Receives: Superior opthalmic vein Inferior opthalmic vein Sphenoparietal sinus Drains via: Petrosal sinuses Basilar plexus Pterygoid plexus Connection: Circular sinus Contains: CN III, IV, V1, V2, VI Skull Base Anatomy Cavernous Sinus Meckel’s Cave • Posterior aspect of cavernous sinus • Gasserian ganglion (sensory root ganglion of CN V)
  27. 27. Skull Base Anatomy Superior Orbital Fissure • CN III, IV, V1, VI • Middle meningeal artery- orbital branch • Recurrent meningeal artery • Superior opthalmic vein Inferior Orbital Fissure • Infraorbital artery, vein, and nerve (V2 branch) Optic Canal • Optic nerve • Opthalmic artery
  28. 28. Orbital landmarks • Superior orbital fissure • Optic canal • Inferior orbital fissure – other end of foramen rotundum • Ant. And Post. Ethmoidal foramina • Anterior & Posterior ethmoidal arteries • Foramina = constant guide to level of ethmoid roof as position of fronto-ethmoid suture.
  29. 29. Skull base Pathology • Intra-axial – brain lesions/tumours • Extra-axial – lesions from adjacent structures, usually from below skull base • Metastatic eg breast, lung, prostate ca
  30. 30. Extra- axial pathology of anterior and middle cranial fossae • Paranasal sinus Lesions • Malignant: SCC, adenocarcinoma, sarcoma, melanoma, olfactory neuroblastoma, adenoid cystic, distant mets. • Benign: mengioma juvenille nasopharyngeal angiofibroma, fibrous dysplasia, Inverting papilloma, fibro osseous disease
  31. 31. Paranasal sinus malignancy • Maxillary sinus carcinoma • SCC commonest • T4b- involvement of dura, brain, clivus, nasopharynx (inoperable) • Multiplanar CT with contrast and MRI to fully assess – unilateral sinus mass with bony wall destruction (sinus wall is rarely expanded). • MRI good for perineural, dural and intra cranial spread
  32. 32. Extra-axial pathology of posterior cranial fossa • CPA lesions • Acoustic neuromas, meningioma’s, other neuromas (rare eg VII nerve neuroma), epidermoids, glomus tumours, arachnoid cysts, haemangiomas • Rare – mets, chordomas, chondrosarcoma, lipoma, dermoids, teratomas • Petrous apex lesions • Cholesterol granuloma, cholesteatoma, meningioma, asymmetric petrous( extra bone marrow – can be mistaken for neoplasm!), mucocele, petrous ICA aneurysm, giant cell tumour.
  33. 33. Intra-axial Pathology of skull base • Brainstem – gliomas (commonest CPA tumour in children) • Cerebellum/ brain – medulloblastomas, astrocytomas, haemangioblastomas • Fourth ventricle – choroid plexus papillomas, ependymomas Brainstem Glioma
  34. 34. Case 1
  35. 35. Chondrosarcom a 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 circumscribed margins
  36. 36. Chondrosarcoma Origin: • 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 undifferentiated
  37. 37. Case 2
  38. 38. 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 Diff. Dx: • Chondroma • Chondrosarcoma • Clivus meningioma
  39. 39. Chordoma Origin • 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
  40. 40. Case 3
  41. 41. Glomus Tumor Glomus jugulare CT/MRI Findings: • Center: jugular foramen • Limit: hyoid bone • Enhance w/ contrast • Salt and pepper appearance on MRI • Bone erosion
  42. 42. Glomus Tumor Origin: • Chemoreceptor cells Location: • 10% multiple • glomus jugulare: jugular bulb • glomus tympanicum: cochlear promontory; Clinical: • Pulsatile tinnitus • Hearing loss • arrythmia, BP fluctuation
  43. 43. Hints and tips! • MRI-Talk about signal intensity (low vs high) • Marrow=hyper intense • Bone=hypointense • High flow blood vessels – black on MR • MRI T1weighted • water=black • Fat=white • Look for CSF around spinal cord to see • MRI T2 weighted • Water=white • Fat=black • Nodes show up brighter on T2 as cystic necrosis
  44. 44. Hints and tips - MRI • Lipomas signal suppresion on STIR • Adenoid cystics – peri neural spread seen only after gadolinium contrast on T1 – makes them shine! • Parapharyngeal space –Schwannomas and paragangliomas are behind carotid so push carotid antero-medially and up to skull base. Best seen on T1 after gadolinium • Paragangliomas – look shaggy, light up quickly with contrast then wash out • Schwannomas – look smooth and have delayed enhancement after contrast Paraganglioma on T2 Lipoma at petrous apex
  45. 45. Hints and tips - MRI • Glomus Jugulare – slow growing, shows irregular bone destruction • Fibrous dysplasia – inhomogenous enhancement • Meningioma – bright on T1 and light up with gadolinium, broad based and dural tail
  46. 46. For Other powerpoint presentatioins of “ Skull base 360° ” I will update continuosly with date tag at the end as I am getting more & more information click www.skullbase360.in - you have to login to slideshare.net with Facebook account after clicking www.skullbase360.in

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