The value of magnetic resonance imaging in the diagnosis of intracranial meningiomas.

Thirty-two patients suspected by Computed Tomography (CT) of having a meningioma were additionally imaged by Magnetic Resonance. Of these, seven patients had an eventual diagnosis other than meningioma. This represents a positive value of 76% for the diagnosis of meningioma by CT. Magnetic resonance imaging (MRI) improved positive predictive value to 86%. A diagnosis other than meningioma was made by MRI with greatest confidence when tumour signal intensity was either much greater or much less than that of grey matter. Comparison of Inversion Recovery (IR) and spin echo (SE) sequences showed IR to be superior for demonstration of supratentorial meningiomas. SE images were superior to IR in demonstrating calcification. MRI was of value in showing anatomical relationships, due to its multiplanar capacity and in demonstrating vessel patency. CT was generally superior in defining meningiomas and in demonstrating calcification.