MRI in the diagnosis of cystic meningiomas: surgical implications.

Nine cases of cystic meningioma diagnosed by MRI are described. All cases were surgically confirmed. The lesion was extra-axial with a clear dural attachment. On T1-weighted images the solid component was iso-hypo-intense in 6 cases and iso-hyperintense in 3; on T2-weighted images it was hyperintense in 7 cases, iso-intense in 2. After i.v. injection of gadolinium, the solid component enhanced in all cases and a "dural tail" were visible in 8 cases. No gadolinium enhancement of the cyst wall was observed in Nauta's types II and III. The authors found MRI to be very useful for diagnosis of cystic meningioma but insufficient for differential diagnosis between types II and III according to Nauta. This aspect requires further study, especially in view of the implications of this differentiation in terms of surgical management.