MR Imaging in the Presurgical Workup of Patients with Drug-Resistant Epilepsy

BACKGROUND AND PURPOSE: Whether an epileptic lesion is detected with MR imaging depends on the quality of the images and the expertise of the reader. We analyzed the role of 1.5-T MR imaging in the presurgical evaluation of patients with drug-resistant epilepsy at one center. METHODS: In a 2-year prospective study, 385 patients with drug-resistant epilepsy under-went standardized MR imaging at 1.5 T. We analyzed whether lesions were detected, whether they were precisely characterized by MR imaging, and whether lesion characterization allowed us to estimate seizure outcomes. RESULTS: Lesions were found on MR images in 318 patients (83%). Following presurgical evaluation, 209 (66%) underwent surgery, and 109 (34%) did not. Freedom from seizures was achieved in 130 (70%) of 186 patients. Nine (14%) of 66 patients without an MR imaging lesion underwent surgery; histopathologic findings were unrevealing in seven patients, and five (56%) achieved freedom from seizures. Hippocampal sclerosis was the most common lesion (52%) and correctly characterized in 101 (97%) of 104 patients. Glioneuronal tumors (20%) were some-times imprecisely characterized: Four nonenhancing gangliogliomas were mistaken for foca