Skull base tumors & perineural spread radiology ppt This powerpoint presentation includes important anatomy and important pathology of skull base lesion with its imaging feature as well as its ct mri image. This will help alot. this will help for radiology resident as well as ent .

1. Dr Pradeep
MD Resident

2.  The skull:
 Calvarium
 Facial bones
 Mandible
The calvarium is the brain case and comprises the skull vault and skull
base.

3. The inner aspect of the skull base is made up of the
following bones from anterior to posterior:
 The orbital plates of the frontal bone, with the
cribriform plate of the ethmoid bone and crista
galli in the midline
 The sphenoid bone with its lesser wings
anteriorly, the greater wings posteriorly, and body
with the elevated sella turcica in the midline
 Part of the squamous temporal bone and the
petrous temporal bone; and
 The occipital bone

22. • May arise from the cranial base or reach it, either from an intracranial
or extracranial origin.
Role of imaging
Diagnosis
Extent of disease – criteria of surgical resectability
Treatment planning – surgical approach
Follow up – recurrence Vs post treatment changes

24.  Sinonasal malignancy (e.g., squamous cell
carcinoma)
 Epithelial: Nasopharyngeal carcinoma
 Non epithelial: Olfactory neuroblastoma,
juvenile nasopharyngeal angiofibroma

25.  Sellar and parasellar: pituitary adenoma,
craniopharyngioma, cavernous sinus
meningioma
 Juvenile nasopharyngeal angiofibroma,
nasopharyngeal carcinoma
 Clivus and petrooccipital fissure: chordoma,
chondrosarcoma

26.  CP angle tumors: Schwannoma,
meningioma, endolymphatic sac
tumors
 Clival: Chordoma,
Chondrosarcoma
 Foramen magnum: Meningioma

28. ANTERIOR SKULL BASE

29. • Lesions arise:
– Extracranially
• From the nasal vault, frontal and ethmoid sinuses
– Intrinsically
• From the skull base itself
– Intracranially
• From the brain, meninges and CSF spaces

30. • Lesions arise:
–Extracranially
• From the nasal vault, frontal and ethmoid sinuses
– Intrinsically
• From the skull base itself
– Intracranially
• From the brain, meninges and CSF spaces

31. • Most arise from the nose and paranasal sinuses
Common Benign Lesions
Mucocoele
Polyposis
Inverted papilloma
Osteoma
Common Malignant Lesions
Squamous cell carcinoma
Rhabdomyosarcoma
Adenoid cystic carcinoma
Esthesioneuroblastoma

32.  Olfactory neuroblastoma
 Olfactory plate or superior nasal cavity
 Mean age: 45 years
 Intracranial extension upto 25 %
 Unilateral within the upper nasal cavity  expand
the nasal cavity and ethmoid air cells bilaterally
penetrate the orbit and cribriform plate

33.  CT:
 Expansive homogeneous soft tissue mass occupying
the ethmoid air cells, invading the cribriform plate
and breaking through to the anterior cranial fossa
 A relatively uniform enhancement
 Occasional focal calcification
 Nasal bony remodeling and erosion at cribiform
plate, rarely hyperostosis.
 MR:
 Minimal to moderate gadolinium enhancement.
 Large tumoral lesions may present solid and cystic
components.
 The presence of small cysts at the tumor-brain
interface are typical.

34. A. Skull base diagram
B. Coronal bone windows CT scan
shows the lesion extending
through the cribiform plate into
the anterior cranial fossa (arrow)
C. Coronal T1-Weighted image
postgadolinium
D. T2-weighted MR image shows
the tumor filling the right nasal
cavity. Note the obstructive
phenomenon into the ethmoid
sinus and the small tip
intracranial component

35.  Stage criteria:
 T1 tumor that affects the nasal fossae and/or paranasal sinuses (excluding the
sphenoid)
 T2 affects the nasal fossae and paranasal sinuses (including the sphenoid)
with infiltration of the lamina cribosa
 T3 extends to the orbit or anterior cranial fossa without invasion of the dura
mater
 T4 includes cerebral invasion.

36.  may arise from the nasal cavity, paranasal sinuses, pharynx, or the major
and minor salivary glands.
 Squamous cell carcinoma is the most common tumor of the paranasal
sinuses
 Adenocarcinoma most frequently occurs in the upper nasal cavity or in
the ethmoid sinuses
 Adenoid cystic carcinomas arise from the major and minor salivary glands
and characteristically infiltrate diffusely, especially along perineural
pathways
 Neuroendocrine carcinomas are malignancies of the exocrine glands
found in the normal nasal and paranasal mucosa.

38.  Mesenchymal malignant tumor
 Often children
 Most often affects orbit, nasopharynx and paranasal sinuses
 Possibility of subarachnoid spread

39.  CT:
 Usually show an aggressive infiltrative soft tissue mass
 Areas of bone destruction are frequent
 Variable enhancement
 MRI:
 Large infiltrating enhancing soft tissue mass lesion with
bone destruction
 Signal intensity is similar to the muscle on T1-weighted and
hyperintense on T2-weighted
 Diffuse often marked and heterogeneous enhancement

40. A. Axial
B. Skull base diagram
C. Sagittal and
D. Coronal SE- weighted T1 MR post-
contrast demonstrate a large infiltrating
enhancing soft tissue mass lesion with
bone destruction involving right frontal
sinus, right nasal cavity and orbital roof not
crossing of the midline. The intra-cranial
epidural invasion across the frontal base is
best seen on coronal imaging

41.  Non-Hodgkin's lymphoma (NHL)
 CT:
 Bulky, lobular soft tissue mass in nasal cavity and sinus
 Isodense, moderate homogeneous enhancing mass
 Bone remodeling or destruction, nasal septal involvement
 MR:
 Intermediate, homogeneous signal on T1
 Low-intermediate on T2
 Moderate, diffuse enhancement
 Low ADC on DWI

42.  A. Axial SE-T1 weighted MR image
shows a nasal cavity infiltrating
mass involving the ethmoid cells.
Note the hyperintense signal in
the ethmoid cells due to
obstructive sinusitis . The medial
wall of the left orbit is expanded
by the tumor. C. Coronal T2-
weighted MR image shows a
homogenous hypointense
infiltrating mass affecting
nasosinusal area with a small tip
extending through the cribriform
plate D. Diffusion weighted MR
image (DWI) shows a strongly
hypointense ADC map due to high
cellularity of the mass.

43. • Lesions arise:
– Extracranially
• From the nasal vault, frontal and ethmoid sinuses
–Intrinsically
•From the skull base itself
– Intracranially
• From the brain, meninges and CSF spaces

44. Intrinsic anterior skull base lesions
Fibrous dysplasia
Paget disease
Osteopetrosis

45.  Developmental anomaly
 Monostotic, polyostotic or diffuse (McCune-Albright syndrome)
 The skull and facial bones
 10-25% of patients with monostotic fibrous dysplasia
 50% of patients with polyostotic fibrous dysplasia
 Sarcomatous degeneration is rare

46.  CT:
 Expansive lesion of medullary bone space with variable attenuation
 Pagetoid mixed pattern (25 %)
 Sclerotic "ground-glass" density (56 %) or cystic (20%).
 Cystic areas may be present
 Encroaches on skull base canals and foramina
 MR
 Localized fibrous dysplasia often mimics a tumor as fibrous tissue can
enhance brilliantly after the injection of contrast material
 Low signal on T1 and T2 images with more heterogeneous signal pattern
in "active" areas ( high signal )
 Characteristic areas of variable to strong contrast enhancement

47.  A. and B. Axial
Bone CT shows
expansive bone
lesion with
variable
attenuation.
Centrally lucent
lesions with
thinned but
sclerotic borders
and ground-glass
density are seen.

48.  rare
 most common in the frontal and parietal bones of the calvarium
 slow-growing lesions
 typically occur in women in the fourth and fifth decades of life

49.  CT:
 Expansive, well-circumscribed area of rarefaction with a sunburst pattern
of trabeculations radiating from a common center
 Usually no reactive sclerosis at the margins
 Honeycomb or soap-bubble configuration is characteristic
 Enhancing soft-tissue masses with lytic bone destruction
 Mastoid, jugular, magnum, lacerum foramen can be involved
 MRI:
 Variable.
 Low signal intensity on T1 and high signal intensity on T2
 Enhancement occurs with contrast administration
 Hypervascular lesion and a delayed blush on dynamic sequences

50.  A. Axial and Coronal CT
C+ shows a expansive,
well circumscribed area
of rarefaction with a
sunburst pattern of
trabeculations radiating
from a common center.
The mass is originating
in the right frontal bone
and is extending into the
right orbit in a patient
presenting with
proptosis. C. and D.
radiography reveals a
sunburst pattern
resembling
osteosarcoma.

51. • Lesions arise:
– Extracranially
• From the nasal vault, frontal and ethmoid sinuses
– Intrinsically
• From the skull base itself
–Intracranially
•From the brain, meninges and CSF spaces

52. • Arise from:
– Meninges
– CSF spaces
– Brain

53.  Common, benign intracranial tumors
 Arise from arachnoid cells of the duramater.
 Located in the midline of the anterior fossa between the crista galli and
the tuberculum sellae.
 Usually bilateral but may be asymmetric
 The most common presenting symptom - subtle change in mental
function, headache or seizure disorder.

54.  CT:
 Hyperdense, homogeneous enhancing
mass
 Frequent dural tail (35%)
 Calcifications (25%)
 Variable bone involvement (destruction,
erosion or hyperostosis)
 MRI:
 Isointense on T1 weighted, iso or
hyperintense on T2-weighted
 Bright homogeneous contrast
enhancement
 Dural tail enhancement (80%)

55.  MRI criteria of meningioma malignancy:
(a) significant peritumoral oedema
(b) absence of calcium deposition
(c) nonhomogeneous contrast enhancement
(d) cysts within the lesion
(e) poorly defined, irregular borders

56.  Malignant mesenchymal tumors arising from pericytic cells
 Account for less than 1% of all vascular neoplasms
 Mean age ranging from 37 to 44 years
 Inevitable tendency to recur locally and metastasize distally
 Long term follow up necessary
 Dural-based and show white matter "buckling".

57.  CT:
 Soft tissue hyperdense extraaxial mass
 Heterogeneous enhancement
 Low density cystic or necrotic areas are common
 Peritumoral oedema is frequent
 Bone erosion (90%)
 MRI:
 Isointense on T1 weighted, iso or hyperintense on T2-weighted with
cortical gray matter
 Prominent internal serpentine signal voids, suggesting vessels
 Heterogeneous enhancement
 Dural tail (50%)

58.  Contrast enhanced CT shows
hyperdense heterogeneously
enhancing extraaxial mass
occupying the right middle
fossa and anterior fossa with
bone erosion. The mass reach
the anterior cranial fossa
eroding the planum
sphenoidale and the middle
fossa through optic canal and
superior orbital fissure.

62.  An uncommon, highly vascular tumor that affects adolescent boys
 The blood supply of these lesions is primarily from the external carotid
artery (ECA) and in some cases from the internal carotid artery (ICA).
 The site of origin - the region of nasopharynx and the sphenopalatine
foramen.
 The intracranial involvement is relatively frequent (10% to 36%) but rarely
goes beyond the duramater

63.  CT:
 Expansive soft tissue mass with homogeneous avid
enhancement
 Involvement of the pterygopalatine fossa is generally
associated with anterior remodeling of the posterior
wall of the maxillary sinus (Holman Miller sign).
 MRI:
 Low signal intensity on T1-weighted with brightly
homogeneous enhancement on T1 post-gadolinium
 Hyperintense on T2-weighted images
 Internal foci of punctate low signal intensity
represent tumor vessels

64.  Typically benign tumors
 Account for approximately 15% of all primary brain tumors
 Location:
 Sphenoid wings (50%),
 Tuberculum sella and olfactory groove (40%)
 Posterior fossa (8%).
 Extension through the lateral orbital wall is common - slowly progressive,
painless unilateral exophthalmos and decreased visual acuity
 Can extend extracranially via skull base foramen or by destruction and
direct extension of the middle cranial fossa

65.  CT:
 The soft-tissue component enhances intensely after the administration of
contrast material
 Focal areas of destruction, erosion or hyperostosis
 MRI:
 T1 and T2-weighted images show extra-axial mass similar to parenchymal
intensity
 Bright enhancement after Gd
 Extraaxial component is better seen on T1 + Gd coronal plane

66.  Coronal SE-T1 MRI shows a
dumbbell-shaped
homogeneously enhanced
extraaxial mass. Note the
cavernous sinus
involvement medially. B.
Skull base diagram C. Axial
CT Scan at maxillary sinus
level reveal the bulky
extracranial parapharyngeal
component.

67.  10 to 15% of primary brain tumors
operated upon in US
 5% of pituitary adenoma become
invasive and may grow to gigantic sizes
(>4 cm in diameter).
 May invade skull base extending into
anterior/middle/ posterior fossae

68.  CT:
 Large invasive mass without separate identifiable pituitary mass,
extending inferiorly invading sphenoid
 May destroy upper clivus
 Focal areas of bone destruction and erosion that can contain floccular
calcification
 Heterogeneously intense enhancement
 MRI:
 Isointense on T1 and on T2-weighted images
 Extraaxial mass similar to parenchymal intensity
 Early, intense, but heterogeneous enhancement after Gd
 Cyst and hemorrhage are common

69.  A.and D.Axial CT bone scan shows a large lytic expansive lesion of the sellar and parasellar region. Note the typical
benign bone margins. B. Coronal C Sagittal and E. Post contrast T1-weighted MR images show a large sellar mass with
skull base invasion extending through cavernous sinus and clivus F. Skull base 3D view

70.  Account for approximately 70% of all primary malignancies of the
nasopharynx
 The mean age at diagnosis: 45-55 years.
 A minority of patients have submucosal disease, with normal appearing
overlying mucosa
 Nodal metastases present in the vast majority of patients at the time of
diagnosis (75 - 90%)

71.  CT:
 Large invasive mass in nasopharyngeal area
 May extend into any direction, eroding the base of skull and passing via
the Eustachian tube, foramen lacerum, foramen ovale or directly through
bone into the clivus, cavernous sinus and temporal bone
 MRI:
 Is more sensitive to perineural spread and for demonstrating early bone
marrow changes of infiltration
 Isointense on T1 and on T2-weighted images
 Fluid in the middle ear is a helpful marker
 Prominent heterogeneous enhancement is typical
 Perineural extension

72.  A. Coronal CECT reveals a
mildly enhancing infiltrating
mass arising in lateral
pharyngeal recess destroying
a small area of skull base bone
around the oval and lacerum
foramina. The ipsilateral
cavernous sinus is infiltrated
and carotid artery is
entrapped. Masticator space
muscles are also infiltrated. B.
Skull base diagram C. Axial
CT Scan shows the
permeative pattern with oval
foramen widening

73.  Rare, slow-growing malignant neoplasms of embryonic notochordal
derivation
 Age at onset is 20-40 years
 Account for less than 1% of all intracranial tumors
 Approximately 35 % affect the skull base
 Clivus (spheno-occipital synchondrosis) is the most often location, others
are: sphenoid (30%) and petrous apex

74.  CT:
 Enhancing soft-tissue masses with lytic bone
destruction (95%)
 Often shows areas of calcification
 Jugular, magnum, lacerum foramen can be involved
 MRI:
 Isointense to slightly hypointense on T1-weighted
 Typically mass projects in mid-line posteriorly
indenting pons characteristic appearance termed
'thumb sign".
 Classically hyperintense on T2-weighted images
 May contain areas of decreased signal intensity
corresponding to calcification or hemorrhage (T2*)
 Heterogeneous enhancement occurs with contrast
administration (Honeycomb pattern)
 Vascular encasement is the rule (80%)

75.  Rare primary cartilaginous benign bone tumor
 Accounts for 1% of all primary bone tumors
 Squamous temporal bone is the commonest site of occurrence in skull
 CT:
 Expansive intermediate or low density mass
 Lytic nature of the lesion and areas of calcification
 MRI:
 Cystic polylobulated lesion, hypointense on T1-weighted and hyperintense
on T2-weighted.

76.  A. Axial T2-weighted MR
image shows a high signal
intensity erosive mass
affecting retromaxillary
space. B. Skull Base
diagram C. Sagittal T1-
weighted MR image shows
a hypointense
heterogeneous mass with
middle fossa extension. D.
Coronal T2-weighted MR
image shows a extensive
involvement of maxillary
sinus

77.  a slow-growing, malignant cartilaginous tumor
 Account for approximately 6% of all skull base lesions
 Specific sites of involvement:
 parasellar region
 cerebellopontine angle
 facial region (sphenoethmoid and maxillary bone)

78.  CT:
 Characteristic chondroid calcifications in the tumor matrix (arc, ring-like,
stippled and amorphous calcifications) – 50 %
 Bone erosion and destruction (50%) sharply defined edges.
 Variable enhancing soft-tissue mass
 MRI: (less specific)
 Hypointense relative to the brain on T1-weighted images
 Hyperintense on T2-weighted images
 Heterogeneous internal areas of decreased signal represent calcification
 Heterogeneous enhancement

79.  Axial CT scan shows a destructive lytic lesion of clivus and petro-occipital fissure. Small foci of calcifications within
the tumor matrix are shown. The carotid canal is involved. B. Coronal SET2 MRI reveals a hyperintense tumor with
small hypointense foci. D. Skull base diagram E. Axial Fat-supression T2-weighted MR image shows the
characteristic hyperintensity mass with medial extension into prepontine cistern

80.  Benign congenital lesions of ectodermal origin
 Most occur in the region of the cerebellopontine angle and spheno-
temporal suture
 The distinction between dermoid and epidermoid lesions important
prognostically
 Usually contain a varying combination of lipid, liquid cholesterol, whorls
of hair, calcifications and decomposed epithelial cells producing typical
appearances

81.  CT:
 Low attenuation mass similar to cerebrospinal fluid
 Fatty density areas within the mass
 Scattered subarachnoid fat droplets foci when rupture
 Enhancement is rare but can sometimes be seen around the
margin of the tumor
 Geographic pattern of skull base erosion
 Calcification occurs in only 15-20% of cases

82.  MRI:
 Slightly hyperintense or isointense relative to gray matter on T1-WI ( tends to
vary with the lipid content)
 Isointense relative to CSF on T2-weighted images
 The center of the epidermoid usually has an internal architecture with areas
of heterogeneity
 Enhancement of portions of the rim may be seen
 Typically shows restricted diffusion
 Not completely suppressed on FLAIR sequence giving heterogeneous
appearance in contrast to arachnoid cysts

83.  A. Coronal T1-Weighted and B. T2-Weighted MR images show a non-enhance large cystic appearance
mass (hypo T1 and Hyper T2). C. Coronal CT Scan shows the extensive skull base involvement with
"remodeling", erosions and lytic appearance areas. D. Sagittal T1-Weighted and E. Axial T1-Weighted
MR images postcontrast show hyperintense peripheral fatty foci.

84.  Neurilemmoma
 Arise from the nerve sheath and consist of
Schwann cells in a collagenous matrix
 Slowly-growing
 Localization:
 vestibular schwannomas are the most common
followed by trigeminal and facial schwannomas
and then glossopharyngeal, vagus, and spinal
accessory nerve schwannomas

85.  CT:
 Large, sharply demarcated, fusiform or dumbbell mass
 Iso - hypoattenuating relative to brain parenchyma
 Calcification or areas of hemorrhage
 Homogeneous enhancement
 Remodeling of the adjacent skull base
 Smooth enlargement of skull base foramina and fissures
 MRI:
 Isointense or slightly hypointense relative to gray matter on
T1-weighted images
 Hyperintense on T2-weighted images.
 Gadolinium enhancement is typically homogeneous
 Intratumoral nonenhanced cystic components may be
marked

86.  V2 schwannoma A. T1-weighted MR image and B. Postcontrast T1-weighted MR image shows a large
mass in the pterygopalatine fossa with extension into the left orbital apex through orbital fissure.
Marked Peripheral enhancement of tumor with hypovascular cystic areas within the tumor. C. Fat-
suppression T2-weighted MR image D. Skull Base diagram E. Coronal SE-T2 show a characteristic well
defined high signal intensity mass remodeling sphenoid bone.

87. Includes:
– clivus below the sphenooccipital
synchondrosis
– petrous temporal bone
– pars lateralis and
– squamae of occipital bone
• CP Angle – IAC cistern
• Temporal bone
• Clival and paraclival
• Jugular foramen
• Foramen magnum
Location

89. • AICA loop flow void on high-resolution T2 MR
– Will not prominently enhance on Tl1C+ MR
– Subtle enhancement in lAC on TI C+ MR may be mistaken for small acoustic
schwannoma.
• Choroid plexus protruding through lateral recess of 4th ventricle
– T1 C+ MR shows enhancing bilateral tear-shaped masses of CPA cistern
– Symmetry &. characteristic appearance make diagnosis
• Cerebellar flocculus is a lobule of cerebellum projecting into
posterolateral aspect of CPA cistern
– Signal follows intensity of cerebellum on all MR sequences
• Marrow space foci in walls of lAC can mimic lAC tumor on Tl C+ MR images
– Correlate location of foci with lAC cistern
– Bone CT of T-bone may be necessary to identify this normal variant
• High jugular bulb
• Prominent jugular tubercles

91. • Normal structures, when unusually prominent, trouble radiologist
evaluating CPA – lAC.
• AICA loop flow void on high-resolution T2 MR
– Will not prominently enhance on Tl1C+ MR
– Subtle enhancement in lAC on TI C+ MR may be mistaken for small acoustic schwannoma
• Choroid plexus protruding through lateral recess of 4th ventricle
– T1 C+ MR shows enhancing bilateral tear-shaped masses of CPA cistern
– Symmetry &. characteristic appearance make diagnosis
• Cerebellar flocculus is a lobule of cerebellum projecting into posterolateral aspect of CPA cistern
– Signal follows intensity of cerebellum on all MR sequences
• Marrow space foci in walls of lAC can mimic lAC tumor on Tl C+
MR images
– Correlate location of foci with lAC cistern
– Bone CT of T-bone may be necessary to identify this normal variant
• High jugular bulb
• Prominent jugular tubercles

92.  Can occur either as a part of a generalized disease (Multiple myeloma) or a
local entity
 When the skull is involved, most occur in the calvarium and the skull base
is rarely affected
 Neuropathy due to the direct compression of nerves or nerve groups in
their intracranial course

93.  CT:
 Well demarcated solitary intraosseous lytic tumor with non-sclerotic
margins
 Occasionally aggressive with bone destruction and involvement of
adjacent structures
 Lytic mass with scalloped, poorly marginated, non-sclerotic margins
 Multiple calcifications are often visible
 MRI:
 Iso-hypointense on T1 weighted images
 Moderate signal intensity on T2 weighted images (high cellular tumor)
 Moderate homogeneous contrast enhancement with central
inhomogeneity

94.  A. Axial bone CT Scan
shows a diffuse
destructive lytic areas in
central skull base with
sellar, basisphenoid and
ethmoid involvement.
B. Skull base Diagram
C. and D. Axial
postcontrast CT show a
moderate enhancement
infiltrative soft tissue
mass involving both
central skull base and
right petrous bone.

95.  Carcinoma of the breast, lung, kidney and prostate.

96.  CT:
 Infiltrative soft tissue mass with bone erosion
 More frequent: Lytic mass with scalloped,
poorly marginated, non-sclerotic margins.
 May be Sclerotic (e.g Prostate) or expansive
( thyroid and kidney)
 Multiple calcificications often visible
 MRI:
 Iso-hypointense on T1 weighted images
 Moderate signal intensity on T2 weighted
images (in high cellular tumors)
 Moderate heterogeneous contrast
enhancement with central necrosis
 Fat saturation necessary to distinguish
enhancement from normal hyperintense
marrow

97. Jugular
foramen
• Pars nervosa
• (smaller anteromedial
compartment)
• CN IX
• Pars vascularis
• (larger posterolateral
compartment)
• CN X and XI
• Jugular vein

98.  Paraganglioma
 Slow growing vascular tumor
 the most common tumor of the
temporal bone

100.  CT:
 Well-defined enhancing soft-tissue masses
within the jugular foramen
 CT shows characteristic permeative destructive
bone changes: initially, erodes the superolateral
margin of the jugular foramen and jugular spine
with subsequent extension to the mastoid and
adjacent occipital bone
 Significant intracranial and extracranial
extension may occur, as well as extension within
the sigmoid and inferior petrosal sinuses
 May extend superolaterally from jugular
foramen into the middle ear
 Neural infiltration common

101.  MRI:
 Highly vascular tumor on MRI is characteristic
 Increased T2W signal intensity and decreased T1W signal intensity, with
intense enhancement after gadolinium injection
 Numerous, prominent internal flow voids resulting in "salt-and-pepper"
pattern
 Gradient recall echo (GRE) MR sequences can demonstrate the blood
vessels within the tumors better than spin echo sequence.

102.  A. Axial and B. Axial and C. postcontrast T1-weighted MR images show a space-occupying lesion destroying the
petrous bone with intense enhancement expanding the jugular foramen. D. Dynamic contrast Fast-SPGR shows the
hypervascular nature of the lesion. E. Sagittal postcontrast T1-weighted MR images show a second space-occupying
lesion in the internal jugular space representing vagal glomus tumor.

103.  Schwannoma
 Rhabdomyosarcoma
 Foramen magnum meningioma

104.  Common: V2, V3 and VII
 Stm no dominant mass seen
 Perineural spread feature only
detectable abnormality
 Direct imaging signs
1) thickening and enhancement of
affected nerve.
2) abnormal enhacement in Meckel’s
cave.
3) lateral bulging of cavernous sinus dural
membrane.
 Indirect signs
1) foraminal enlargement or destruction
in CT
2) neuropathic atrophy of muscles
3) obliteration of normal fat plane

107. 1. Anterior Cranial Fossa
2. Middle/Central Cranial Fossa
3. Posterior cranial fossa
Laterally by the petrous ridges and in the
midline by the posterior clinoid processes
and dorsum sellae
The sphenoid ridge and anterior clinoid
processes