CYSTIC MENINGIOMAS - MR CHARACTERISTICS AND SURGICAL CORRELATIONS

PURPOSE: To describe the MR appearance of cystic meningiomas, and to c orrelate the MR appearance with the surgical and neuropathologic findi ngs. METHODS: Eight patients with cysts associated with meningiomas we re studied on a 1.5-T MR system. Unenhanced sagittal T1- and axial T2- weighted images were obtained in all patients. Axial and coronal gadop entetate dimeglumine-enhanced T1-weighted spin-echo images were obtain ed in seven patients. Additional sagittal T1-weighted spin-echo contra st-enhanced images were obtained in four patients. RESULTS: The cystic components were intratumoral and eccentric in two cases, intraparench ymal in one case, and extraparenchymal (trapped cerebrospinal fluid) i n five cases. Cyst wall enhancement was present in two of seven cases performed with intravenous gadopentetate dimeglumine. There was no cor relation between cyst signal intensity and cyst content. A preoperativ e diagnosis of cystic meningioma was possible in all eight cases. CONC LUSIONS: MR demonstrates the extradural location of the tumor and its cystic component, correlates well with the surgical presentation and t he neuropathologic results, and allows the preoperative diagnosis of c ystic meningioma based on the MR findings. Division into three types o f cysts aids the neurosurgeon, who must decide whether total resection is feasible. To obtain total resection and reduce the risk of recurre nce with an intratumoral cyst, the surgeon must ensure that the plane of resection is in fact between the thin enhancing membrane of the tum or cyst and the adjacent arachnoid. In cases in which the cyst is trap ped cerebrospinal fluid or intraparenchymal in location, the cyst wall adjacent to or within the brain parenchyma is not included in the res ection.