Neuroimaging in partial epilepsy: Structural magnetic resonance imaging

Magnetic resonance imaging (MRI) is a noninvasive technique that has been shown to be the structural neuroimaging procedure of choice in evaluating patients with partial or localization-related epilepsy. The diagnostic yield of MRI has been confirmed in patients with partial epilepsy related to mesial temporal sclerosis (MTS) or foreign-tissue lesions. Magnetic resonance imaging may be used preoperatively to identify patients with intractable partial epilepsy who have surgically remediable epileptic syndromes. Preoperative MRI studies are predictive of long-term seizure outcome in patients receiving surgical treatment. Analysis of hippocampal formation size has also been shown to correlate with the neurocognitive outcome following temporal lobe surgery. A recent development involving subtraction ictal single photon emission computed tomography (SPECT) coregistered with structural MRI (SISCOM) has important clinical applications. SISCOM studies are more sensitive and specific than visual side-by-side interpretation of interictal and ictal SPECT scans. Also, SISCOM images have been shown to have prognostic importance in patients undergoing surgical treatment for epilepsy.