Thickening of dura surrounding meningiomas: MR features.

Thickening of the dura in continuity with a convexity meningioma was noted on T1-weighted magnetic resonance (MR) images in seven patients. In five cases the corresponding CT image of the lesions was typical of meningioma. In two other cases the CT image of the lesions was atypical, owing to cyst formation in one and extensive edema in the other. After intravenous injection of paramagnetic contrast medium in four patients, the thickened dura demonstrated contrast enhancement at a variable distance from the tumor. In three patients the thickened dura was confirmed surgically. Pathology, available in one case, showed the thickened dura to correspond to tumoral extension within or around the dura. Magnetic resonance demonstration of thickening of the dura in continuity with a mass at the cerebral convexity may prove to be of importance in the differentiation of atypical lesions on CT and MR, especially with lower field magnets. Moreover, it could provide useful information to the neurosurgeon for more complete resection of the tumor.