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

Area of Science:

• Neuroimaging
• Epileptology
• Metabolic Brain Imaging

Background:

• Mesial temporal lobe epilepsy (mTLE) with hippocampal sclerosis (HS) is a common epilepsy syndrome.
• Understanding the precise localization of metabolic dysfunction is crucial for surgical planning and outcomes.
• Previous studies suggest network involvement, but localized patterns in homogeneous mTLE cohorts require further investigation.

Purpose of the Study:

• To quantify and localize cerebral hypometabolism in a homogeneous cohort of mTLE patients with HS using the PETSurfer method.
• To compare glucose metabolism between hemispheres ipsilateral and contralateral to HS.
• To investigate the extent of hypometabolism in relation to surgical outcomes.

Main Methods:

• Utilized FDG-PET and MRI imaging in patients who achieved seizure freedom (Engel class I) after anterior temporal lobectomy with amygdalohippocampectomy.
• Employed the PETSurfer method for quantitative analysis of glucose metabolism.
• Compared metabolic activity between ipsilateral and contralateral hemispheres relative to HS.

Main Results:

• Significant hypometabolism was identified exclusively in ipsilateral temporal lobe structures (amygdala, hippocampus, temporal pole, superior and middle temporal gyrus) and the ipsilateral thalamus.
• Absence of significant hypometabolism in extratemporal regions suggests limited broader network disruption in these 'pure' mTLE cases.
• Effect sizes for hypometabolism ranged from small to medium, indicating variable metabolic reductions.

Conclusions:

• Findings support a localized epileptogenic focus in HS-related mTLE with favorable surgical outcomes.
• The localized hypometabolism pattern in this homogeneous group may differ from more complex epileptic pathologies.
• Further research with larger, diverse cohorts and control groups is recommended to validate and generalize these findings.