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| T1 coronal post gad | T1 axial post gad | T2 axial |
Diagnosis: Meningioma
Meningiomas are usually dural based, intensely enhancing extraaxial masses presenting in woman between the ages of 40 and 60 and contain progesterone and estrogen receptors. They are the most common primary CNS tumor of non-glial origin. Typical locations are parasagittal, over the convexities and the sphenoid ridge. They may be seen in association with neurofibromatosis type II and are multiple in up to 9% of patients, many of whom have NF II. Meningiomas may be intraventricular in 2% of cases. They are hyperdense on CT and 1/4 may have some calcification. Hemorrhage is unusual but cystic change may be seen. Meningiomas are typically isointense to gray matter on T1 while T2 signal is more variable. A dural tail may be seen due to their extraaxial location as well as hyperostosis of the overlying calvarium. On angiography they usually demonstrate the "mother in law sign" since the vascular staining typically comes early and stays late. Although in this case early blush is not a feature. A dural based metastasis may mimic meningioma although a single metastasis of this size is unusual. Hemangiopericytoma is a mesenchymal neoplasm of uncertain origin and is a rare vascular tumor representing less than 1% of all primary CNS neoplasms. Their age of onset is younger than in meningioma and patients are more commonly men. Hemangiopericytomas are aggressive lesions which tend to invade and metastasize. On CT and MR they typically appear as invasive, enhancing extraaxial masses with flow voids due to the high vascularity. In this case, there is likely some necrosis and methemoglobin suggested by the bright internal rim on T1 pre-gad. The T2 signal of this rim is tough to tell for sure. The dark foci on T1 are probably flow voids. The combination here of an extraaxial, intensely enhancing, non-invasive convexity mass with non-shunting vascular blush is most compatible with meningioma. Related Cases
