The Role of Diffusion Tensor Imaging in the Evaluation of Adult Epilepsy

Background Epilepsy affects approximately 12 million persons in India. Conventional MRI fails to detect microstructural white matter abnormalities in a significant proportion of patients. Diffusion tensor imaging (DTI) offers quantitative evaluation of white matter microstructure through fractional anisotropy (FA) and apparent diffusion coefficient (ADC) metrics. This study evaluates the role of DTI and fibre tractography in characterising white matter microstructural changes in adult epilepsy and to assess the diagnostic value of FA as a quantitative biomarker. Materials and Methods A prospective observational study was conducted at the Barnard Institute of Radiology, Madras Medical College and RGGGH, Chennai. Twenty-one adult epilepsy patients and 19 age- and gender-matched healthy controls underwent brain MRI on a Siemens Avanto 1.5T scanner. DTI was post-processed using the FDT diffusion toolbox. Results Three tracts showed statistically significant FA reductions in epilepsy cases: superior longitudinal fasciculus (0.476 ± 0.074 vs 0.570 ± 0.053, p < 0.001), corpus callosum genu (0.733 ± 0.125 vs 0.806 ± 0.069, p = 0.0298), and inferior longitudinal fasciculus (0.360 ± 0.092 vs 0.418 ± 0.086, p = 0.0473). The SLF remained significant in MRI-negative cases (p = 0.0008), with AUC 0.855 on ROC analysis. Conclusion DTI detects white matter microstructural abnormalities in adult epilepsy beyond what is visible on conventional MRI. The superior longitudinal fasciculus FA is the most diagnostically sensitive single-tract biomarker in this cohort, supporting routine DTI inclusion in epilepsy neuroimaging protocols at Indian tertiary centres. Keywords Diffusion tensor imaging; Epilepsy; Fractional anisotropy; White matter; Superior longitudinal fasciculus; Corpus callosum; Inferior longitudinal fasciculus; Fibre tractography.