White Matter and Subcortical Gray Matter Microstructural Integrity in Mesial Temporal Lobe Epilepsy: A Combined Diffusion Tensor and Kurtosis Imaging Study

Abstract

Purpose: The present study aimed to assess structural asymmetry in patients with mesial Temporal Lobe Epilepsy (mTLE) in the diffusion properties of brain white matter and subcortical gray matter tracts using Diffusion Tensor Imaging (DTI) and Diffusion Kurtosis Imaging (DKI). We considered a lower order DTI measure, Fractional Anisotropy (FA), and a higher-order DKI measure, Kurtosis Anisotropy (KA), as quantitative measures of the white matter diffusion properties in facing mTLE. We also made a comparison between these two measures in terms of the sensitivity to capture microstructural changes in concordance with TLE. Materials and Methods: Thirty-two subjects with mTLE participated in this study. All the cases underwent multi-shell diffusion MRI acquisition. The subjects were grouped according to their epileptogenic side of the brain (19 Left-sided and 13 Right-sided TLE). Each group were analyzed separately using FSL package, then laterality analysis based on Tract-Based Spatial Statistics (TBSS) was performed on FA and KA images. After each analysis the left side of the patients’ brain was flipped and subtracted from the right side of the patients’s brain, and a voxel-wise z-score comparison was applied to find the significantly different areas. Results: The results showed a considerable laterality effect on the temporal lobe white matters both in FA and KA, more emphasized in patients with Right-sided mTLE. Conclusion: It can be concluded that these two measures, even though extracted from skeletonized images, can serve as decent biomarkers of laterality in case of mTLE, when the conventional MRI fails to capture the laterality.

Keywords

• Microstructural Integrity
• Mesial Temporal Lobe Epilepsy
• Laterality
• Seizure Zone
• Epileptogenic Side
• Diffusion Tensor Imaging