Abstracts

Rationale: Diffusion tensor imaging (DTI) can noninvasively measure and visualize the diffusion of water molecule in brain tissue, and DTI tractography can depict the fiber trajectory of brain white matter (WM). Epilepsy is a common chronic neurological disorder in children, whose seizures are transient signs and symptoms of abnormal, excessive or synchronous neuronal activity in the brain. The purpose of the present study was to detect the abnormalities of WM and the fiber trajectory in the epileptic regions using DTI. Methods: Twelve children (age = 11.91 ± 6.44, 8 male and 4 female) with epilepsy and 12 healthy children (age = 12.32 ± 3.42, 8 male and 4 female) were studied. All patients had one or more epileptic areas defined by intracranial recordings, magnetic resonance imaging (MRI) and magnetoencephalography (MEG). In addition, all patients underwent epilepsy surgery. Volumetric MRI and DTI data were obtained for all participants using a 3T MRI scanner. To obtain DTI data, a 46-section, diffusion weighted, spin-echo echo-planar imaging scan were acquired in the axial plane. Diffusion-weighted scans were acquired in 12 optimized directions. We calculated the fractional anisotropy (FA), perpendicular (lambda (upper left and right quadrants)) and parallel (lambda (vertical line)) diffusivity in a series of predetermined epileptic areas. All these data were compared and analyzed between patients and normal controls using Statistical Parametric Mapping analysis package (SPM5). Results: Children epileptic group showed a significantly decrease in FA in the epileptic areas determined clinically. Higher diffusivity in direction perpendicular to the axons was detected in the WM structures of the patients, but no significant difference in parallel diffusivity was detected between patients and normal controls. WM fiber trajectories between epileptic areas increased significantly. Conclusions: The results have demonstrated that the WM around the epileptic areas were significantly disorganized. The increases of fiber trajectories imply that epilepsy may result in stronger connection between epileptic areas so that the epileptic discharges can propagate via the extra fibers from epileptogenic zones to secondary epileptic areas.