Magnetic Resonance Imaging (MRI) Volumetric Measurements of Hippocampus in Intractable Temporal Lobe Epilepsy: Comparison With Visual Analysis.

Abstract

The purpose of our study was to compare the sensitivity of magnetic resonance imaging(MRI) volumetric measurements of the hippocampal formation with that of subjective visual assessment performed on standard MRI seans and temporal lobe protocol MRI seans in detecting hippocampal sclerosis (HS). Thirty-nine patients with intractable temporal lob epilepsy were studied at 1.5 T. Temporal lobe protocol MRI seans consisted of three-dimensional (3D) IR and 3D T2 weighted images. In addition, all patients were scanned with FLAIR sequences with 4 mm slices. Volumetric analysis was performed on the oblique coronal inversion-recovery (IR) three-dimensional (3D) volume images. Volumetric analysis demonstrated unilateral hippocampal atrophy (HA) in 28 patients,bilaterally symmetric HA in 2 patients, and bilateral asymmetric HA in 3 patients. Although the visual assessment of temporal lobe protocol MRI scans correctly lateralized the patients with unilateral and bilateral symmetric HA by volumetric analysis, none of patients with bilaterally asymmetric HA was deteeted by visually. in 48% of patients withunilateral or bilateral HA which was deteeted with the visual assessment of temporal lobe protocol MRI seans, the results of standard MRI seans were normal. When MRI seans for the evaluation of patients with intractable temporal lobe epilepsy are done with temporal lobe protocol, visual assessment is similar to volumetric analysis in deteeting unilateral HS but is unlikely to identify bilateral HS in some patients. Standard MRI seans, on the other hand, are inadequate for diagnosis of HS.