This document discusses meningiomas, the most common type of brain tumor. It notes that meningiomas arise from arachnoid cap cells rather than the dura, and ionizing radiation is the only established environmental risk factor. The document describes the various types and grades of meningiomas, their typical appearance on CT and MRI scans, and imaging features that can help differentiate them from other lesions that may appear similar. Treatment depends on the tumor location and extent.

1. Dr. SARFARAZ AHMAD
MODERATOR – DR S N PRASAD

7. Most common of all
intracranial neoplasms.
Arise from arachnoid
"cap" cells rather than
from the dura.
Ionizing radiation is the
only established
environmental risk

8. The most common is monosomy of chromosome 22 (60%) --
usually exhibit fibrous or transitional histology and originate along
the posterior or superior cerebral hemispheres, the posterior and
lateral skull base, and the spinal cord.
Non-NF2 Meningiomas - Have mutations in other "driver genes
(TRAF7, KLF4, AKT1, and SM), usually benign and originate from
the medial skull base and anterior cerebral hemispheres.
Meningothelial, secretory, and microcystic histologies are common.

9. Typical (I)
Atypical (II) Anaplastic/Malignant (III)
•meningothelial, fibrous,
transitional, psammomatous,
•microcystic, secretory, and
angiomatous
chordoid and clear cell papillary and rhabdoid
Meningiomas can be solitary (90%) or multiple.
Multiple meningiomas occur in NF2 as well as in multiple
meningiomatosis syndrome.

10. Tumor location is the single most important feature
regarding therapy since it practically defines the terms of
surgical intervention.

11. On computed tomography (CT)
imaging,
•60% of meningiomas are
hyperdense to cortex
•Up to 25% contain calcification,
which is associated with slow
growth and lower grade
•Adjacent bone exhibits
hyperostosis in 20%
•small number of all grades have
been associated with osteolysis

12. •Meningiomas are usually
isointense to cortex on all
magnetic MRI sequences
•Over half cause
perilesional vasogenic
oedema
•A cerebrospinal fluid
(CSF) cleft is often seen
between
•CSF cysts may become
proteinaceous and
unsuppressed
on fluid suppressing
sequences.

16. In general, T1WI offer little to no specificity
whereas T2W images can give information about
histological
consistency.
subtype,
Meningiomas
vascularity, and
hyperintense on
T2WI are usually soft, more vascular, and more
frequently of syncytial or angiomatous subtype.
Tumors hypointense or on T2WI tend to have
harder consistency and are more of fibroblastic
or transitional subtype.

20. •Approximately 25% of TMs demonstrate calcification.
•Focal globular or more diffuse sand-like ("psammomatous")
calcifications occur.

22. •Another typical
meningioma is
imaging characteristic of
hyperostosis of the adjacent
calvarium in 18–50% of cases.
•Osteoma, fibrous displasia, Paget’s disease, and hyperostosis
frontalis may imitate the hyperostosis typically seen in
meningiomas.

26.  A useful feature in confirming the extra-axial
location of the suspected meningioma is the inward
bowing of the gray–white junction of the adjacent
brain parenchyma often called ‘white matter
buckling’.

28. A linear enhancement along the dura mater, on
either side of meningioma on contrast-enhanced
MRI. This sign is not specific to meningioma..

29. The triple criteria for DTS are: (1) Presence of at
least two consecutive sections through the tumor
at the same site in more than one imaging plane;
(2) Greatest thickness adjacent to the tumor and
tapering away from it; and (3) Enhancement
more intense than that of the tumor itself.

32. •Meningioma (the most common)
•Pleomorphic xanthoastrocytoma
•Glioblastoma
•Chloroma
•Dural plasmacytoma
•Primary CNS lymphoma
•Sarcoidosis
•Vestibular schwannoma
•Cerebral metastases
•Syphilitic gumma
•Medulloblastoma
•Desmoplastic infantile astrocytoma and ganglioglioma

35. Several imaging features such as peritumoral
edema, cystic
transformation,
changes,
intracranial
lipomatous
hemorrhage,
irregular contour, poorly defined margins, and
ring enhancement are considered unusual.

36. About 60% of meningiomas are associated with
PTE. It is more common with large lesions but
may be extensive with small ones. Reports have
found that severe edema is associated with more
aggressive syncytial and angioblastic cell types,
and mild-to-moderate edema associated with
fibroblastic and transitional cell types.

38. The term cystic meningioma has been used to
describe two different morphologies:
• Intratumoral cavities, and extratumoral
or arachnoid cysts.
•The presence of neoplastic cyst should be
suspected when ring enhancement of the wall is
seen.

41. Lipoblastic meningioma represents a variant in
which there is a metaplastic change of
meningothelial cells into adipocytes. Lipomatous
meningiomas are markedly hypodense on CT
(negative HU) and may have minimal to slight
enhancement within the fatty regions.

43. Spontaneous intracranial hemorrhage associated
with meningioma is an uncommon condition
with incidence 1.3% of all meningiomas. The
most common type of bleeding is subarachnoid
hemorrhage, followed by intracerebral and
intratumoral hemorrhage.

45. •Hyperintensity on DWI.
•Disruption of arachnoid at brain-tumor
interface(loss of CSF cleft sign)
•Heterogenicitiy on contrast enhanced MRI.
Irregular tumor shape(mushrooming).
•Increased CBV on Perfusion imaging

46. •Atypical meningiomas are usually located in the calvarium rather
than the skull base.
•Commonly invade overlying bone and scalp and have little or no
calcification.
•Characterized by microscopic invasion of brain parenchyma,
displaying a less distinct interface with the adjacent cortex.
•Contrast enhancement is more heterogeneous, and there may be
areas of necrosis which do not enhance.
•Higher-grade meningiomas, including atypical and malignant
•Have lower apparent diffusion coefficient

48.  Show complete loss of the CSF cleft, no demarcation between
tumour and brain parenchyma.
 They characteristically mushroom into the brain from their
dural attachment.
 Metastases are very rare (1 in 100,000), but most arise in the
lungs.

51. Advanced MR imaging techniques are usually of
little value in making the diagnosis in patients
with typical imaging findings of meningioma.
Atypical and malignant meningiomas tend to be
markedly hyperintense on diffusion-weighted
MR images and exhibit marked decrease in ADC
values when compared with normal brain
parenchyma.

53. MR spectroscopy may provide additional
information in differential diagnosis.
•The most common finding in meningiomas is a high Cho peak
with low or absent NAA and Cr and variable amounts of lactate.
•Most importantly, high ratio of Ala to Cr has been found in
meningiomas (relatively specific finding).
•MR spectroscopy may differentiate histologically atypical
meningiomas on the basis of lactate peak at 1.3 ppm.

54. En plaque meningiomas is characterised by
diffuse and extensive dural involvement

55.  CPA meningiomas represent the second most
common mass lesions of the CPA, although less
than 5% of all meningiomas occur in CPA.
 Approximately, 80% of masses in the CPA are
acoustic schwannomas and half of the remainder
20% are meningiomas

59. •Intraventricular meningiomas are the most
common trigonal masses in an adult accounting
for approximately 2–5% of intracranial
meningiomas.
•About 80% are located in the lateral ventricle,
15% in the third ventricle, and about 5% within
the fourth ventricle.

61. There are multiple neoplastic and non-neoplastic
entities that clinically and radiographically
mimic meningiomas, including solitary fibrous
tumors, hemangiopericytoma, gliosarcoma,
leiomyosarcoma, dural metastases, Hodgkin’s
disease, plasmocytoma, Rosai Dorfman disease,
neurosarcoidosis, melanocytic neoplasms,
plasma cell granuloma, Tolosa-Hunt syndrome,
and pituitary macroadenoma.