MR characteristics of neoplasms and vascular malformations associated with epilepsy.

We assessed the magnetic resonance (MR) imaging characteristics of two categories of epileptogenic substrates, neoplasms, and vascular malformations, to determine MR sensitivity and typical imaging features. A blinded retrospective analysis was performed on MR scans from 41 patients who had a neoplasm or vascular malformation surgically resected as treatment for medically refractory epilepsy. Abnormalities were assessed for sensitivity of MR detection, prediction of pathologic category, location, calvarial remodelling, signal intensity, and effect on adjacent tissue. Pathologic findings consisted of 33 tumors and 8 vascular malformations. We correctly localized 100% of the 41 lesions and predicted the correct pathologic category for 95% of these lesions. Neoplastic and vascular lesions (NVLs) associated with epilepsy had certain characteristic features. The temporal lobe was the most common site for NVL, involved in 68%. NVL were located in the brain periphery in 85% and remodelled the calvarium in 32%. NVL were associated with mass effect in 61%, volume loss in 1%, and no effect on adjacent tissue in 37%. NVL associated with epilepsy can be detected with high sensitivity using MR imaging. The temporal lobe location, cortical involvement, and calvarial remodelling are findings typical of NVL. MR characteristics can successfully predict the pathologic substrate of these lesions.