MRI Volumetry and Diffusion Tensor Imaging in Temporal Lobe Epilepsy

Epilepsy is one of the most common neurological diseases. It affects about 70 million people worldwide. Temporal lobe epilepsy (TLE) is the most common focal epilepsy and its most frequent cause is hippocampal sclerosis. Approximately one-third of patients with TLE have seizures which fail to respond to drug therapy and they require surgical resection of the epileptic focus. Drug resistant epilepsy (DRE) is associated with neurocognitive and psychological decline, poor quality of life, increased risk of premature death and higher economic burden.

Diagnosis of TLE typically relies on clinical evaluation, MRI to visualize affected areas, such as hippocampal sclerosis and EEG to detect abnormal electrical activity in the temporal lobe's cortical regions. However, both EEG and conventional MRI have limitations. About thirty percent of temporal lobe epilepsy (TLE) cases are negative on MRI, so quantitative diagnosis based on clinical symptoms becomes challenging.

The development of automatic MR volumetry makes it possible to account for hippocampal volume differences that may escape visual detection. MRI volumetry enables to objectively quantify brain volume changes associated with neurological conditions such as Alzheimer's disease, multiple sclerosis and epilepsy. Automated segmentation tools facilitate precise and reproducible analysis of structural brain changes, contributing significantly to early diagnosis, patient monitoring, and therapeutic planning. Progress in neuroimaging has led not only to successful identification of epileptic foci for surgical resection, but also to improve understanding of the microstructural changes in long-standing epilepsy. Diffusion tensor imaging (DTI) has the ability to characterize microstructural abnormalities in epileptic foci and to demonstrate the white matter fibers and tracts participating in the epileptic network. DTI is an MRI technique, which is based upon the ability of MRI to assess the direction and magnitude of water diffusion in tissues in vivo by utilizing the principle of anisotropic diffusion of water molecules in the white matter tracts of the brain.