[¹⁸F]FDG PET metabolic patterns in mesial temporal lobe epilepsy with different pathological types

Area of Science:

• Neuroimaging
• Epileptology
• Pathology

Background:

• Mesial temporal lobe epilepsy (MTLE) is a common form of drug-resistant epilepsy.
• Distinct pathological subtypes of MTLE may influence surgical outcomes.
• [18F]FDG PET is a valuable tool for presurgical evaluation.

Purpose of the Study:

• To investigate [18F]FDG PET patterns in MTLE patients with different pathological types.
• To correlate PET findings with surgical outcomes.
• To provide guidance for predicting long-term prognoses after epilepsy surgery.

Main Methods:

• Retrospective review of MTLE patients undergoing anterior temporal lobectomy (2016-2021).
• Classification into chronic inflammation and gliosis, hippocampal sclerosis (HS), or focal cortical dysplasia plus HS (FCD-HS) based on pathology.
• [18F]FDG PET analysis using standardized uptake value (SUV), SUV ratio (SUVr), and asymmetry index (AI) compared to healthy controls (HCs).

Main Results:

• Seizure freedom rates were 54.55% (gliosis), 62.79% (HS), and 69.23% (FCD-HS) at 2.8 years follow-up.
• Gliosis group showed larger extratemporal hypometabolism, including the ipsilateral insula.
• All MTLE groups exhibited decreased SUV, SUVr, and AI compared to HCs, with no significant inter-group differences.

Conclusions:

• MTLE patients with isolated gliosis had the worst prognosis and distinct insular hypometabolism.
• Prioritize evaluation of hypometabolic regions over [18F]FDG uptake values in presurgical PET scans.
• Degree of hypometabolism in the epileptogenic focus did not correlate with surgical outcomes.