Diploic meningioma contiguous to a contralateral parasagittal meningioma: CT and MR features

A patient with a diploic meningioma is presented. Computed tomography (CT) scan revealed an intradiploic tumor which seemed contiguous at a point to a contralateral, recurrent parasagittal meningioma. On CT, density of the diploic meningioma was similar to that of the parasagittal meningioma, but the contrast study showed that the former enhanced much less than the latter. Magnetic resonance (MR) imaging demonstrated that the diploic tumor was heterogeneous and much less enhanced with Gadolinium-DTPA (Gd-DTPA) than the parasagittal meningioma on T1-weighted image, although they were very similar in signal intensities on T2-weighted and proton density-weighted MR images without Gd-DTPA. Reasons for such marked differences in enhancement patterns are discussed.