Interictal and postictal ¹⁸F-FDG PET/CT in epileptogenic zone localization

Area of Science:

• Neurology
• Nuclear Medicine
• Medical Imaging

Background:

• Refractory epilepsy poses significant diagnostic challenges in localizing the epileptogenic zone.
• 18F-fluorodeoxyglucose positron-emission tomography/computed tomography (18F-FDG PET/CT) is an imaging modality used to assess metabolic activity in the brain.
• Accurate localization of the epileptogenic zone is crucial for surgical planning and patient management.

Purpose of the Study:

• To evaluate the diagnostic performance of 18F-FDG PET/CT in localizing epileptogenic zones.
• To compare the efficacy of 18F-FDG injection during the interictal period versus the postictal period.

Main Methods:

• A cohort of 110 patients with refractory epilepsy underwent 18F-FDG PET/CT.
• Patients were divided into an interictal group (100 patients) and a postictal group (10 patients) based on the timing of 18F-FDG injection relative to seizure activity.
• Reference standards for epileptogenic zone localization included histopathology, surgical follow-up, serial electroencephalography (EEG), long-term video EEG, and magnetic resonance imaging.

Main Results:

• 18F-FDG PET/CT demonstrated higher concordance with reference standards in the postictal group (90%) compared to the interictal group (60%).
• In the postictal group with concordant findings, 18F-FDG PET/CT identified the epileptogenic zone by showing hypermetabolism in 44.4% and hypometabolism in 55.6% of cases.
• Electroencephalography (EEG) monitoring was essential for correlating imaging findings.

Conclusions:

• Postictal 18F-FDG PET/CT is a valuable tool for localizing the epileptogenic zone in refractory epilepsy.
• The technique can identify the epileptogenic zone through detection of either hypometabolism or hypermetabolism.
• Integrating EEG monitoring enhances the utility of 18F-FDG PET/CT for epilepsy localization.