PETSurfer-Based Brain Segmentation in Patients with Temporal Lobe Epilepsy and Associated Hippocampal Sclerosis

In a homogeneous cohort of mesial temporal lobe epilepsy (mTLE) patients with hippocampal sclerosis (HS), this study utilizes the PETSurfer method to quantify and localize areas of cerebral hypometabolism.

We selected patients from the University Clinical Center of Serbia who all underwent anterior temporal lobectomy with amygdalohippocampectomy and achieved seizure freedom (Engel class I). Our analysis involved integrating FDG-PET and MRI imaging to compare glucose metabolism between the hemispheres ipsilateral and contralateral to HS.

The quantitative PETSurfer approach identified significant hypometabolism restricted to the ipsilateral temporal lobe structures-the amygdala, hippocampus, temporal pole, superior and middle temporal gyrus-and the ipsilateral thalamus. The lack of significant hypometabolism in extratemporal regions indicates that these 'pure' mTLE cases may not involve the broader network disruptions typically associated with more extensive epileptic pathologies. The effect sizes ranged from small to medium, indicating variable degrees of metabolic reduction across different structures.

These findings highlight the localized nature of the epileptogenic focus in HS-related mTLE with good surgical outcome. However, the small sample size and potential cohort bias, necessitate caution in generalizing these results. Future research would benefit from a comparative approach incorporating a control group, providing a broader context for interpreting these hypometabolic patterns.