Abstracts

Rationale: To investigate whether there are white-matter (WM) abnormalities in neocortical epilepsy, we used tensor magnetic resonance imaging (MRI) to extract supratentorial WM parameters from individual raw images with automated region-of-interest (ROI) registrations. Methods: Sixteen patients having neocortical seizures with secondarily generalised convulsions and 16 age-matched normal subjects were imaged with high-resolution and diffusion tensor MRIs. Fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) were measured in each supratentorial neural pathways. Through a white matter parcellation map which comprises commissural, association and projection tracts aligning with individual brain were used to register the ROIs. Then, diffusion parameter histograms were created and histogram-based measures (peak height and peak location) were derived. Results: Patients had lower FA values at fornix(cres) stria terminalis (FX/ST), sagittal stratum (SS), and posterior thalamic radiation (include optic radiation) (PTR) and higher FA values at posterior limb of internal capsule (PLIC) compared to controls (p < 0.05). Significant increases were found in tapetum (TAP) and PLIC of AD and in TAP, FX/ST, SS, and PTR of RD. Patients showed significant increase of the peak height frequency in splenium of corpus callosum and PLIC of the AD histogram and in cingulum (cingulated gyrus) of the RD histogram. There were also significant rightward shift in external capsule of the AD histogram and in SS and PTR of RD histogram ad shown in Figure 1. Conclusions: The proposed method allows for group comparisons of whole-brain ROI analyses based on original MRIs. Patients with neocortical seizures and secondary generalisation had microstructural anomalies in WM. The changes of WM are relevant to the early onset, progression and severity of epilepsy.