Diagnostic Imaging of Cerebellopontine Angle Masses
-
Upload
mohamed-zaitoun -
Category
Health & Medicine
-
view
1.092 -
download
0
Transcript of Diagnostic Imaging of Cerebellopontine Angle Masses
![Page 1: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/1.jpg)
C.N.S.Cerebellopontine Angle Masses
![Page 2: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/2.jpg)
Mohamed Zaitoun
Assistant Lecturer-Diagnostic Radiology Department , Zagazig University Hospitals
EgyptFINR (Fellowship of Interventional
Neuroradiology)[email protected]
![Page 3: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/3.jpg)
![Page 4: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/4.jpg)
![Page 5: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/5.jpg)
Knowing as much as possible about your enemy precedes successful battle
and learning about the disease process precedes successful management
![Page 6: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/6.jpg)
Cerebellopontine Angle Masses1-Vestibular schwannoma (Acoustic Neuroma)2-CPA Meningioma3-Epidermoid Cyst4-Trigeminal Schwannoma5-Arachnoid Cyst6-Aneurysm7-Metastases8-Skull base / Temporal bone tumors9-Skull base infection10-CPA Lipoma
![Page 7: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/7.jpg)
The CPA is region between the pons & cerebellum and the posterior aspect of the petrous temporal bone
Important structures of the CPA includes 5th , 7th & 8th cranial nerves & AICAMost lesions of the CPA are extra-axial & located in the CPA cistern itself
![Page 8: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/8.jpg)
![Page 9: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/9.jpg)
1-Vestibular schwannoma (Acoustic Neuroma)a) Incidenceb) Locationc) Radiographic Featuresd) Differential Diagnosis
![Page 10: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/10.jpg)
a) Incidence :-Commonest CPA mass , 80%-More in females-Benign tumor of Schwann cell origin-90% are solitary , multiple schwannomas are
commonly associated with NF2
![Page 11: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/11.jpg)
b) Location of Schwannoma :1-CPA (CN VIII , most commonly from superior
portion of vestibular nerve), 90%2-Trigeminal nerve (CN V)3-Other intracranial sites (rare) :-Intratemporal (CN VII)-Jugular foramen / bulb (CNs IX , X , XI)4-Spinal cord schwannoma5-Peripheral nerve schwannoma6-Intracerebral schwannoma (very rare)
![Page 12: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/12.jpg)
c) Radiographic Features :1-Mass2-CT3-MRI
![Page 13: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/13.jpg)
1-Mass :->2 mm difference between left and right IAC-Erosion and flaring of IAC-IAC > 8 mm-Extension into CPA ( path of least resistance ) : ice-cream
cone appearance-Marked brainstem compression may occur and produce
obstructive hydrocephalus-Significant signal heterogeneity with cystic or hemorrhagic
areas is more typical of vestibular schwannoma than meningioma
![Page 14: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/14.jpg)
-Intracanalicular component representing “the cone”
-The CPA component representing the “ice cream”
![Page 15: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/15.jpg)
2-CT :-Isodense by CT-Presents as a solid (small) or complex (large)
enhancing mass with an intracanalicular component that expands the porus acousticus and internal auditory canal
![Page 16: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/16.jpg)
![Page 17: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/17.jpg)
CT+C
![Page 18: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/18.jpg)
CT , Bilateral acoustic neuroma , NF2
![Page 19: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/19.jpg)
CT+C , Bilateral acoustic neuroma in NF2
![Page 20: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/20.jpg)
3-MRI :*T1 : 70% hypointense, 30% isointense*T2 : Hyperintense*T1+C : Dense enhancement : -Homogeneous if small-Heterogeneous if large*May contain cystic degenerative areas +/-
hemorrhage within large lesions*Marginal arachnoid cysts
![Page 21: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/21.jpg)
T1
![Page 22: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/22.jpg)
T1
![Page 23: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/23.jpg)
T1
![Page 24: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/24.jpg)
T1
![Page 25: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/25.jpg)
T2
![Page 26: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/26.jpg)
T2
![Page 27: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/27.jpg)
T2
![Page 28: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/28.jpg)
T2
![Page 29: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/29.jpg)
T1+C shows a rounded tumour in the right CPA with extension into the internal auditory meatus , the IAM is expanded , this is the ice-cream cone sign
![Page 30: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/30.jpg)
T1+C
![Page 31: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/31.jpg)
T1+C
![Page 32: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/32.jpg)
T1+C
![Page 33: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/33.jpg)
T1+C
![Page 34: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/34.jpg)
T1+C
![Page 35: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/35.jpg)
T1+C
![Page 36: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/36.jpg)
T1+C
![Page 37: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/37.jpg)
T1+C
![Page 38: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/38.jpg)
d) Differential Diagnosis :1-From CPA masses2-From Neurofibroma
![Page 39: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/39.jpg)
1-From CPA masses : Schwannoma Meningioma Epidermoid
1-Epicenter IAC Dural based CPA
2-CT Density Isodense Hyper/Isodense Hypodense
3-Calcification None Frequent Occasional
4-Porus acusticus/IAC
Widened Normal Normal
5-T2W signal intensity relative GM
Hyperintense 50% isodense Hyperintense
6-Enhancement Dense Dense None
![Page 40: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/40.jpg)
Acoustic neuroma Meningioma Epidermoid
![Page 41: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/41.jpg)
2-From Neurofibroma :-Plexiform neurofibromas are unique to
neurofibromatosis type 1 (NF1)-They do not occur primarily in the cranial cavity
but may extend into it from posterior ganglia or as an extension of peripheral tumors
![Page 42: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/42.jpg)
Schwannoma Neurofibroma
1-Origin Schwann cells Schwann cells and fibroblasts
2-Association NF2 NF1
3-Incidence Common Uncommon
4-Location CN VIII > other CN Cutaneous and spinal nerves
5-Malignant degeneration
No 5-10%
6-Growth Focal Infiltrating
7-Enhancement +++ ++
8-T1W 70% hypointense, 30% isointense
Isointense with muscle
9-T2W Hyperintense Hyperintense
![Page 43: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/43.jpg)
2-CPA Meningioma :a) Incidenceb) Radiographic Featuresc) Differential Diagnosis
![Page 44: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/44.jpg)
a) Incidence :-10 % of CPA masses (2nd most common)-Age: 40 to 60 years-Three times more common in females
![Page 45: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/45.jpg)
b) Radiographic Features :1-CT2-MRI3-Angiography
![Page 46: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/46.jpg)
1-CT :a) Signal Intensity b) Morphologyc) Bony Abnormalities
![Page 47: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/47.jpg)
a) Signal Intensity :-Hyperdense (75%) or isodense (25%) on
noncontrast CT-Strong homogeneous enhancement (90%)
(hallmark)-Calcifications , 20%-Cystic areas , 15%
![Page 48: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/48.jpg)
CT
![Page 49: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/49.jpg)
CT
![Page 50: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/50.jpg)
CT
![Page 51: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/51.jpg)
CT
![Page 52: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/52.jpg)
CT
![Page 53: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/53.jpg)
CT+C , left CPA homogeneously enhancing meningioma with a broad base against the petrous bone
![Page 54: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/54.jpg)
b) Morphology :-Round unilobulated sharp margin (most
common)-Dural tail : extension of tumor or dural reaction
along a dural surface-Edema is absent in 40% because of the slow
growth
![Page 55: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/55.jpg)
c) Bony Abnormalities : 20 %-No changes (common)-Hyperostosis (common)-Bone erosion ( rare , if present may indicate
malignant meningioma )
![Page 56: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/56.jpg)
2-MRI :*T1&T2 :-Tumors are typically isointense with GM*T1+C :-Strong gadolinium enhancement*Dural tail (60%) is suggestive but not specific for
meningioma*Increased vascular flow voids
![Page 57: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/57.jpg)
T1
![Page 58: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/58.jpg)
T2
![Page 59: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/59.jpg)
T1+C
![Page 60: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/60.jpg)
T1+C
![Page 61: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/61.jpg)
T1+C
![Page 62: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/62.jpg)
T1+C
![Page 63: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/63.jpg)
T1+C
![Page 64: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/64.jpg)
T1+C shows the typical appearance of a meningioma with the flat surface against the petrous bone and the dural tails , this tumor is arising anterior to the left IAM , it may extend into the IAM as seen here
![Page 65: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/65.jpg)
3-Angiography :-Spokewheel appearance-Dense venous filling-Persistent tumor blush ( comes early and stays
late ) = Mother’s in law sign-Well-demarcated margins-Dural vascular supply
![Page 66: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/66.jpg)
![Page 67: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/67.jpg)
![Page 68: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/68.jpg)
f) Differential Diagnosis : (see before)-CPA meningiomas can be differentiated from vestibular
schwannomas by virtue of their broad-based attachment to the petrous bone and more homogeneous signal
-They are typically less bright on T2 and enhance uniformly
-A small tongue of tissue may extend into the internal auditory canal but there is usually no expansion
-Peripheral (dural tail) and hyperostosis suggests meningioma
![Page 69: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/69.jpg)
3-Epidermoid Cyst :a) Incidenceb) Locationc) Radiographic Featuresd) Differential Diagnosis
![Page 70: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/70.jpg)
a) Incidence :-5 % of CPA masses-Congenital lesions which account for about 1%
of all intracranial tumours-They result from inclusion of ectodermal
elements during neural tube closure
![Page 71: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/71.jpg)
-Although predominantly congenital, epidermoid cysts are usually very slow growing and as such take many years to present, typically patients are between 20 and 40 years of age
-An uncommon association exists with anorectal anomalies, sacral anomalies and pre-sacral mass and is known as the Currarino triad
![Page 72: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/72.jpg)
b) Location :*Intradural (90 %) >>1-CPA, 40 %2-Suprasellar region3-4th ventricle4-Middle cranial fossa*Extradural ( 10 % ) >>-Most within the skull
![Page 73: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/73.jpg)
c) Radiographic Features :1-CT :-Lobulated lesion with CSF density-No enhancement
![Page 74: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/74.jpg)
![Page 75: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/75.jpg)
2-MRI : CSF-like signal*T1 :-Usually isointense to CSF-Higher signal compared to CSF around the periphery of the lesion
is frequently seen-Rarely shows high T1 signal (white epidermoids)*T2 :-Usually isointense to CSF (65%)-Slightly hyperintense (35%)*T1+C :-No enhancement-Thin enhancement around the periphery may sometimes be seen
![Page 76: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/76.jpg)
*FLAIR :-Often heterogeneous /dirty signal ; higher than
CSF
*DWI :-Useful for differentiation from arachnoid cysts
due to increased signal (due to a combination to true restricted diffusion and T2 shine through) which isn’t seen with arachnoid cyst
![Page 77: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/77.jpg)
T1
![Page 78: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/78.jpg)
T1
![Page 79: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/79.jpg)
T2
![Page 80: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/80.jpg)
T2
![Page 81: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/81.jpg)
T1+C
![Page 82: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/82.jpg)
T1+C
![Page 83: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/83.jpg)
FLAIR
![Page 84: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/84.jpg)
FLAIR
![Page 85: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/85.jpg)
DWI
![Page 86: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/86.jpg)
DWI
![Page 87: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/87.jpg)
ADC
![Page 88: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/88.jpg)
ADC
![Page 89: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/89.jpg)
**N.B. : T2 shine through-Refers to high signal on DWI images that is not due
to restricted diffusion but rather to high T2 signal which (shines through) to the DWI image, T2 shine through occurs because of long T2 decay time in some normal tissue
-This is most often seen with subacute infarctions due to vasogenic edema but can be seen in epidermoid cyst
-To confirm true restricted diffusion one should always compare the DWI image to the ADC
![Page 90: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/90.jpg)
-In cases of true restricted diffusion the region of increased DWI signal will demonstrate low signal on ADC
-ADC is a value that measures the effect of diffusion independent of the influence of T2 shine-through, ADC maps thus portray restricted diffusion such as in ischemic injury , as hypointense lesions relative to normal brain
-In contrast , in cases of T2 shine-through , the ADC will be normal or high signal
![Page 91: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/91.jpg)
d) Differential Diagnosis :1-From Dermoid cyst :-See table
![Page 92: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/92.jpg)
Epidermoid Dermoid
Content Squamous epithelium, keratin, cholesterol
Also has dermal appendages (hair, sebaceous fat, sweat glands)
Location Off midlineCPA most commonParasellar, middle fossaIntraventricular, diploic space (rare)
MidlineSpinal canal most commonParasellar, posterior fossa
Rupture Rare Common (chemical meningitis)
Age Mean 40 years Younger adults
CT density CSF density May have fat
Calcification Uncommon Common
Enhancement Occasional peripherally None
MRI CSF-like signal Proteinaceous fluid
Incidence 5-10 times more common than dermoid
Less common
![Page 93: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/93.jpg)
2-From Arachnoid cyst : (See table)-DWI allows differentiation of epidermoid and
arachnoid cysts :The ADC of an epidermoid cyst is significantly
lower than that of an arachnoid cyst , therefore , epidermoid cysts have high signal intensity on DWI , whereas arachnoid cysts , like CSF , have very low signal intensity
![Page 94: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/94.jpg)
Arachnoid Epidermoid
1-Signal intensity Isointense to CSF on T1Isointense to CSF on PDIsointense to CSF on T2
Mildly hyperintense to CSFHyperintense to CSF on PDIsointense to CSF on T2
2-Enhancement No No
3-Margin of lesion Smooth Irregular
4-Effect on adjacent structures
Displaces Engulfs , insinuates
5-Pulsation artifact Present Absent
6-Diffusion imaging Follows CSF Hyperintense to CSF
7-FLAIR imaging Suppresses like CSF Hyperintense to CSF
8-Calcification No May occur
![Page 95: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/95.jpg)
4-Trigeminal Schwannoma :-Similar in appearance to vestibular
schwannoma but arising from the V cranial nerve
![Page 96: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/96.jpg)
Trigeminal schwannoma of right gasserian ganglion with smooth margins , relatively low signal in T1 ( A) and high homogenous signal intensity on T2 ( B )
![Page 97: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/97.jpg)
Trigeminal Schwannoma of right gasserian ganglion , relatively low signal on T1 ( A ) and high heterogeneous signal intensity on T2 ( B ) , note normal Meckel’s cave ( curved arrow ) on ( C )
![Page 98: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/98.jpg)
T1+C shows normal non-enhancing Meckel’s cave on the right side (arrow) , in the left Meckel’s cave , a heterogenous enhancing mass (arrow head) is seen extending in the cavernous sinus , trigeminal schwannoma
![Page 99: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/99.jpg)
A homogeneous , enhanced , dumbbell-shaped right trigeminal schwannoma involving the cisternal part of the nerve and Meckel cave
![Page 100: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/100.jpg)
5-Arachnoid Cyst :-Benign CSF-filled lesion that is usually
congenital-Although most arachnoid cysts are
supratentorial , the CPA is the most common infratentorial location
-Arachnoid cyst will follow CSF signal on all sequences including complete suppression on FLAIR , unlike epidermoid cyst , arachnoid cyst doesn’t have restricted diffusion
![Page 101: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/101.jpg)
Arachnoid cyst (a) T1 shows an arachnoid cyst with signal intensity similar to that of CSF stretching the left seventh and eighth cranial nerve complex (arrow) , (b) T2 shows the cyst displacing the vascular structures of the CPA (arrowheads)
![Page 102: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/102.jpg)
6-Aneurysm :-Large aneurysms arising from the vertebrobasilar
system (PICA , AICA , vertebral artery or basilar artery) may appear as well-defined avidly enhancing CPA lesion and may be initially mistaken for a schwannoma or meningioma on CT+C
-On MRI , clues to a vascular etiology would be flow void and pulsation artifacts , MRA or CTA are diagnostic
![Page 103: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/103.jpg)
Aneurysm in a 75-year-old man with hypoglossal nerve palsy , (a) T2 shows a thrombosed aneurysm of the right PICA with focal calcification (arrowhead) , note the normal right hypoglossal canal (arrow) , a finding inconsistent with a schwannoma , (b) T1+C shows homogeneous enhancement of the organized thrombus which completely fills the aneurysm
![Page 104: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/104.jpg)
7-Metastases :-See Brain Tumors 8-Skull Base / Temporal Bone Tumors :-e.g. Glomus tumors & cholesterol granuloma 9-Skull Base Infection :-Gradenigo's syndrome (osteomyelitis of the petrous
apex) and malignant otitis externa10-CPA Lipoma :-See brain tumors
![Page 105: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/105.jpg)
Melanoma in a 58-year-old woman with a left cerebellar syndrome , (a) CT shows a hyperattenuating melanoma of the left CPA , (b) T1 shows a well-defined extraaxial mass at the posterior edge of the petrous bone , the high signal intensity is suggestive of melanin , (c) T1+C shows a normal left internal auditory canal (arrow) and lack of dural tail enhancement
![Page 106: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/106.jpg)
Metastases in a 67-year-old man with lung cancer, (a) T2 shows a metastasis of the right CPA that mimics a vestibular schwannoma but with unusual associated middle ear retention ( ) , ∗ (b) T1+C shows intense enhancement of the lesion which extends into the cochlea (arrow) , note the presence of another enhancing lesion at the tip of the right petrous bone (arrowhead)
![Page 107: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/107.jpg)
Paraganglioma (a) T2 shows a huge paraganglioma destroying the petrous bone and invading the right CPA , massive flow voids (arrowheads) reflect the hypervascularity of the lesion , note the thin layer of trapped CSF (arrow) between the mass and the brainstem which indicates an extraaxial origin , (b) T1 shows the suggestive salt-and-pepper appearance of the paraganglioma , (c) T1+C shows intense enhancement of the lesion along with unusual dural tail enhancement of the meninges (arrows)
![Page 108: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/108.jpg)
Cholesterol granuloma , (a) T1 shows a cholesterol granuloma at the apex of the right petrous bone with typical high signal intensity , an additional suggestive feature is the thin hypointense rim (arrowheads) which represents expanded cortical bone of the petrous apex , (b) T2 shows that the granuloma has heterogeneous signal intensity surrounded by a hypointense rim (arrowheads) , (c) T1+C shows the normal right trigeminal nerve (arrow) at the top of the mass
![Page 109: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/109.jpg)
Apex petrositis in a 50-year-old woman with Gradenigo syndrome at clinical evaluation , (a) T1 shows an irregular lesion at the tip of the petrous apex (arrow) , (b) T1+C shows right-sided apex petrositis as an enhancing lesion along the courses of cranial nerves V and VI (arrow)
![Page 110: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/110.jpg)
CPA lipoma (a) Axial CT scan shows a well-defined hypoattenuating lipoma of the left CPA , (b) T1 shows that the lipoma has signal intensity similar to that of subcutaneous fat
![Page 111: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/111.jpg)
T1 shows CPA lipoma
![Page 112: Diagnostic Imaging of Cerebellopontine Angle Masses](https://reader036.fdocuments.in/reader036/viewer/2022062523/587171a61a28ab58758b79e3/html5/thumbnails/112.jpg)