Assessment of the Effect of Temporal Lobe Epilepsy on the White Matter of the Limbic System and White Matter Related to Lesions Causing Epilepsy Using Diffusion Tensor Imaging and Tractography

Abstract
Background: Diffusion tensor imaging (DTI) is one of recent advances in magnetic resonance imaging. It provides a three-dimensional (3D) localization of white matter tracts. Because there is widespread propagation of neuronal firing in seizure disorders via neuronal networks, cortical and subcortical regions including the limbic system can be affected despite a single seizure focus. DTI demonstrates diffusion changes in these regions.
Aim of Study: To detect the role of DTI and tractography techniques in the assessment of effects of temporal lobe epilepsy on the white matter of limbic system (cingulum and fornix) and white matter related to organic lesions causing epilepsy.
Patients and Methods: This is a prospective study included 40 patients diagnosed clinically as having temporal lobe epilepsy (TLE) and twenty control subjects. The patients and control groups are examined by conventional magnetic reso-nance imaging (MRI) followed by DTI and tractography. Tractography technique was used to draw the cingula, fornices and other white matter tracts related to the lesions causing epilepsy as well as to measure their fractional anisotropy (FA).
Results: Cingulum and fornix affection was only in the form of reduction of their FA. The affection of the white matter tracts related to organic lesions were in the form of: Reduction of their FA at the same site of the lesions, displace-ment by mass lesion with no signs of infiltration and missing part of the tracts in one patient with right temporo occipital area of encephalomalcia).
Conclusions: DTI and tractography technique help in assessment of the integrity of white matter tracts and could detect various pattern of their affection in patient with temporal lobe epilepsy.