Investigation of microstructural abnormalities in white and gray matter around hippocampus with diffusion tensor imaging (DTI) in temporal lobe epilepsy (TLE)

Abstract

Objective: The objective of this study was to apply diffusion tensor imaging (DTI) to investigate microstructural abnormalities in temporal lobe epilepsy (TLE) with and without hippocampal sclerosis (HS).

Materials: Totally, 19 patients with TLE with HS and 23 patients with TLE without HS were included. Fiber tracking fibers focused on the parahippocampal cingulum (PHC), cingulate gyrus (CG), and fornix (FORX). Fractional anisotropy (FA) and mean diffusivity (MD) values were obtained, and hippocampal volumes were measured.

Results: Compared with the contralateral side, for the HS group, FA values of ipsilateral CG and FORX were significantly decreased, and MD value of ipsilateral hippocampus was significantly higher, with significantly declined ipsilateral hippocampal volume. For the MRI-Neg group, FA values of ipsilateral CG, FORX, and hippocampus were significantly decreased, while MD values of ipsilateral FORX and hippocampus were significantly higher. Moreover, for the MRI-Neg group, the FA value of contralateral PHC was significantly decreased. Fractional anisotropy values of ipsilateral CG for both groups were significantly decreased, and FA value of ipsilateral FORX for the HS group was significantly decreased. Furthermore, MD value of ipsilateral hippocampus for the HS group was significantly higher, and FA value of ipsilateral hippocampus for the MRI-Neg group was significantly decreased. In addition, ipsilateral hippocampal volumes for both groups were significantly decreased. Fractional anisotropy value of ipsilateral CG and FORX had a correlation with the seizure frequency.

Conclusion: Diffusion tensor imaging can detect microstructural abnormalities in brain from patients with TLE, which might be hard to find with routine Magnetic Resonance Imaging (MRI) sequence.

Keywords: Diffusion tensor imaging (DTI); Fiber tracking; Hippocampal sclerosis; Temporal lobe epilepsy (TLE).