MR imaging of peripheral intracranial neoplasms: extraaxial vs intraaxial masses.

In an effort to determine magnetic resonance (MR) features of peripheral brain tumors that allow accurate localization. 11 extraaxial neoplasms were compared with 11 peripheral intraaxial tumors. The MR findings most often seen in extraaxial lesions include interruption of bone, white matter buckling, widening of adjacent subarachnoid space or cistern, and medial displacement of pial arteries or veins. Invasion of the cortex without white matter buckling, as well as flattening and lateral displacement of the surface veins, was most often seen in intraaxial lesions. Neither simple contiguity to a bony or dural surface nor vasogenic edema is a reliable predictor of intra- vs extraaxial masses.