| Discussion: Meningiomas represent 15% of all brain tumors. They are the most common extra-axial tumors in the brain and the most frequently occurring tumors of mesodermal or meningeal origin.
In males, the prevalence of meningiomas is 1.2 cases per 100,000 population. In females, the prevalence is 2.6 cases per 100,000 population. The ratio of meningiomas to gliomas in a Mayo Clinic group was 1:2. Relative frequency of intracranial tumors in large series by Zimmerman attributed 12.5% of tumors to meningiomas.
Survival rates from surgical series are 82%, 72%, and 60% at 2, 5, and 10 years, respectively.
Meningiomas are rare in patients younger than 20 years, and if present, commonly are associated with neurofibromatosis type 2. Of all intracranial meningiomas, 1-2% occur in children and adolescents.
CT-
-Invasion of surrounding dura frequently provokes an osteoblastic response, causing hyperostosis. Hyperostosis is seen in 15-20% of patients. -CT is the imaging modality used best for demonstrating calcification of meningiomas.
-The CT nature of the calcification may be nodular, fine and punctate, or dense. -CT can show acute tumor hemorrhage and widened vascular grooves in the calvarium. -Homogeneous masses with attenuation similar to the surrounding brain make up 25-33% of meningiomas.
-67-75% hyperattenuating compared with the brain.
-Meningiomas can exhibit extensive edema.
-Inhomogeneous enhancement can result due necrosis or rare hemorrhage. -Contrast-enhanced CT displays moderate-to-strong homogeneous enhancement in most tumor.
-A study by Naidich of 136 patients, tumor blush was nodular and nearly homogeneous in 70% of patients.
MRI-
-On nonenhanced T1-weighted images, most meningiomas have no signal intensity difference compared with cortical gray matter.
-T2-images also show the extent of edema. -On MRI and CT, meningiomas exhibit the same enhancement appearance after the injection of contrast medium. Intense enhancement is seen in 85% of tumors. -Meningiomas have a collar of thickened, enhancing tissue that surrounds their dural attachment; this is also known as a dural tail. This sign represents thickened dura which may be either reactive or neoplastic. A dural tail occurs in approximately 65% of meningiomas and 15% of other peripheral tumors; therefore, it is a good predictor of lesion identity. While this radiographic feature is not specific for meningiomas, it is highly suggestive of the diagnosis. | 
CALCIFIED MENINGIOMA
