[Functional imaging (PET and SPECT) in epilepsy]

Area of Science:

• Neurology
• Medical Imaging
• Neurosurgery

Background:

• Epilepsy affects 1% of the population, with many cases originating in the temporal lobe.
• Medication-resistant epilepsy impacts 20-30% of patients, often necessitating surgical intervention.
• Accurate identification of the epileptogenic zone is crucial for successful epilepsy surgery.

Purpose of the Study:

• To evaluate the role of advanced functional imaging techniques in localizing epileptogenic foci for epilepsy surgery.
• To compare the diagnostic accuracy of various imaging modalities in presurgical epilepsy evaluation.

Main Methods:

• Review of Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET), and Single-Photon Emission Computed Tomography (SPECT) in epilepsy.
• Analysis of ictal SPECT and interictal PET (18F-FDG) studies for seizure focus localization.
• Inclusion of benzodiazepine receptor imaging (123I-iomazenil SPECT, 11C-Flumazenil PET) in the evaluation.

Main Results:

• MRI identifies structural lesions in 80% of epilepsy patients, but correlation with epileptogenic foci can be variable.
• Ictal SPECT demonstrates high sensitivity (90-97%) for detecting seizure onset zones.
• Interictal PET (18F-FDG) shows 80-85% sensitivity for metabolic abnormalities.
• Combined functional imaging (perfusion/metabolism and receptor binding) offers superior visualization of epileptogenic sites.

Conclusions:

• Functional imaging modalities like PET and SPECT are essential tools in the presurgical evaluation of medically refractory epilepsy.
• These techniques significantly enhance the accuracy of identifying the epileptogenic zone, reducing the need for invasive monitoring.
• Advanced imaging improves the potential for seizure freedom through targeted surgical resection.