Meningiomas are the most common type of brain tumor. They occur most frequently in females over age 65. While usually benign, some can be more aggressive. On imaging, meningiomas typically appear as well-defined, extra-axial masses that enhance strongly with contrast. More aggressive subtypes may show less distinct borders, heterogeneous enhancement, brain invasion and bone destruction. Advanced imaging techniques like perfusion MRI and MRS can help distinguish between benign versus atypical or malignant meningiomas.

1. Meningioma
DR VAISHAL SHAH
DM NEUROLOGY RESIDENT
GOVT. MEDICAL COLLEGE,KOTA

2. Introduction
Meningioma is the most common of all intracranial neoplasms.
Over a third of all primary intracranial neoplasms.
Female predominance ( F/M – 2/1 ).
Peak occurrence is in the sixth and seventh decades (mean = 65 years).

3. Introduction
Although meningioma accounts for slightly less than 3% of primary brain
tumors in children, meningioma still represents the most common durabased
neoplasm in this age group.
NF2-related meningiomas occur at a significantly younger age compared with
nonsyndromic meningiomas.
Symptoms relate to size and tumor site. < 10% of meningiomas become
symptomatic.

4. Types
WHO grade 1 - most common type, benign.
WHO grade 2 - more aggressive clinical behavior and less favourable outcomes.
The most aggressive form of meningioma, corresponding to WHO grade III, is
anaplastic ("malignant") meningioma.

5. Etiology
Ionising radiation is the only established risk factor.
The dose-related time interval to tumor development varies from 20 to 40
years.

6. Etiology
NF2 mutations are detected in most meningiomas associated with type 2
neurofibromatosis (NF2) and are found in up to 60% of sporadic meningiomas.
NF2 mutant meningiomas originate along the posterior or superior cerebral
hemispheres, the posterior and lateral skull base, and the spinal cord.
Non-NF2 meningiomas are usually benign and originate from the medial skull
base and anterior cerebral hemispheres.

8. Size and Number
Meningiomas vary widely in size.
Most are small (< 1 cm) and found incidentally.
Some—especially those arising in the anterior fossa from the olfactory
groove—may attain large size before causing symptoms.

11. Imaging – CT
Round or lobulated, sharply demarcated, extraaxial dura-based mass that
buckles the cortex inward.
3/4 of meningiomas are mildly to moderately hyperdense compared with
cortex. 1/4 are isodense.
Peritumoral vasogenic edema, seen as confluent hypodensity in the adjacent
brain, is present in about 60% of all cases.

12. CT
The vast majority of meningiomas enhance strongly and uniformly
25% demonstrate calcification. Focal globular or more diffuse sand-like
("psammomatous") calcifications occur.
Frank necrosis or hemorrhage is rare.

13. CT
Bone CT may show hyperostosis that varies from minimal to striking.
Striking enlargement of an adjacent paranasal sinus may occur with skull base
meningiomas.
Bone involvement by meningioma occurs with both benign and malignant
meningiomas and is not predictive of tumor grade.

17. MRI
T1 - Meningiomas are typically iso to hypointense compared with cortex.
T2 - Iso to moderately hyperintense compared with cortex.
CSF-vascular "cleft“ is seen as a hyperintense rim interposed between the
tumor and brain on T2.
A number of "flow voids" representing displaced vessels are often seen within
the "cleft.“
Sometimes a "sunburst" pattern can be identified radiating toward the
periphery of the mass.

18. MRI
FLAIR - Varies from iso- to hyperintense.
Useful for depicting peritumoral edema seen in half of the patients.
Peritumoral edema is related to the presence of pial blood supply and VEGF
expression, not tumor size or grade.
T1+C - Over 95% enhance strongly and homogeneously.
Dural tail is seen in majority. It enhances more intensly and more uniformly
than tumour itself.
Dural tail is not pathognomic.

19. DWI - Most meningiomas do not restrict on DWI.
MRS - Alanine (Ala, peak at 1.48 ppm) peak is sensitive. Glutamate-glutamine (
peak at 2.1-2.6 ppm) and glutathione (peak at 2.95 ppm) may be more specific
potential markers.
Perfusion MR - helpful in distinguishing TM from atypical/malignant
meningiomas. High rCBV in the lesion or in the surrounding edema suggests a
more aggressive tumor grade.

20. Occasionally skull base meningiomas adjacent to a paranasal sinus cause massive
enlargement of the sinus, a condition known as pneumosinus dilatans.

22. Sunburst of vessels

26. Atypical Meningioma
10-15% of all meningiomas.
Most atypical and malignant meningiomas arise from the calvaria. The skull
base is a relatively uncommon location for these more aggressive lesions.
50% of atypical meningiomas invade the adjacent brain. So no cleft is seen.

27. Imaging
Indistinct borders and heterogenous lesion.
Frank bone invasion with osteolysis is common. Better seen on CT.
Absent of CSF – Vascular cleft.
Peritumoral edema.

28. Contrast enhancement is strong but often quite heterogeneous.
ADC is significantly lower in atypical and malignant meningiomas.
Perfusion MR may show elevated rCBV, especially in the peritumoral edema.

29. Clear cell type
atypical meningioma

30. Anaplastic meningioma
Rare
1-3% of meningioma
Male predominance
Imaging triad – Extracranial mass, osteolysis, “mushrooming” intracranial
tumour.

31. Papillary meningioma –
grade 3

32. Thank you