Abstracts

Magnetic resonance imaging (MRI), in addition to its clinical value, has greatly advanced the understanding of structural, functional and metabolic substrates of human epilepsy. Diffusion tensor imaging (DTI) employs this modality to quantify diffusion properties in tissue including fractional anisotropy (FA), relative anisotropy (RA) and mean diffusivity (MD). Using DTI it has been shown that certain white matter regions are different in adult epilepsy patients than in normal subjects (Magn Reson Imaging 2002; 20:511-519), but whether these changes are present at the onset of epilepsy versus develop over time remains uncertain. Further, the degree to which DTI abnormalities are present in pediatric epilepsy remains to be determined. Consequently, callosal regions of white matter in children with a recent epilepsy diagnosis were investigated by DTI and the results presented here., As part of a comprehensive longitudinal brain imaging study, 13 patients with recent onset idiopathic epilepsy (mean age 13.67 [plusmn] 3.14 years) and 12 control subjects (mean age 12.02 [plusmn] 3.07 years) were administered DTI scans. FA, MD and RA maps were created using custom software and regions of interest (ROIs) were created for the genu and splenium of the corpus callosum using MRIcro. FA, MD and RA values were determined for the ROIs using Matlab and statistics were performed using R., Significant differences for all diffusion property indicators between epilepsy patients and controls were evident in the splenium and indicative of a reduction in white matter anisotropy there. Although the genu was found to exhibit a significantly increased FA in epilepsy patients compared to controls, neither RA nor MD was significantly different between the groups, thus the genu was not considered to have conclusively disrupted white matter diffusion., The major finding of this work is that diffusion properties of callosal white matter in the splenium but not genu are significantly deviant from normal values. These findings are evident very early in the course of pediatric epilepsy ([lt] 1 year since diagnosis). Longitudinal investigation of DTI information will provide insight into the course of this abnormality over time.[table1], (Supported by NINDS RO1-44351, NIH NS 2RO1-37738, NIH RO1 RR16591-02.)