UTILITY OF FLUORODEOXYGLUCOSE (FDG)-POSITRON EMISSIONTOMOGRAPHY (PET) SCAN IN DRUG RESISTANT EPILEPSY

Abstract

Background: Drug-resistant epilepsy (DRE) affects nearly 30% of individuals with epilepsy and remains a major therapeutic challenge. Accurate localization of the epileptogenic zone (EZ) is crucial for surgical planning and long-term seizure control. In cases where magnetic resonance imaging (MRI) and electroencephalography (EEG) yield inconclusive results, fluorodeoxyglucose positron emission tomography (FDG-PET) provides a valuable tool for identifying interictal hypometabolism, enhancing the precision of EZ detection.

Objective: To evaluate the diagnostic performance of FDG-PET in localizing epileptogenic zones, its concordance with EEG, and its association with post-surgical outcomes in patients with DRE.

Methods: This cross-sectional observational study was conducted from July to December 2024 at Pak Emirates Military Hospital, Rawalpindi. A total of 96 patients aged 18 to 60 years with a confirmed diagnosis of DRE were enrolled using a convenient sampling technique. FDG-PET and EEG were performed in all cases. Concordance between modalities, diagnostic accuracy (sensitivity, specificity, predictive values), and surgical outcomes were analyzed. PET scans were interpreted by blinded nuclear medicine physicians. Data were analyzed using SPSS version 26.0 with p < 0.05 as the level of significance.

Results: FDG-PET successfully localized EZs in 76 out of 96 patients (79.2%). It showed a sensitivity of 88.2%, specificity of 72.7%, positive predictive value of 84.2%, and negative predictive value of 78.6%. The concordance rate with EEG was 66.7%, with the temporal lobe showing the highest agreement (85.4%, p = 0.001). Post-surgical seizure-free outcomes were significantly higher in patients with positive PET localization (73.7%) compared to those without (10.0%, p < 0.001), with fewer reporting no improvement (5.3% vs. 50.0%).

Conclusion: FDG-PET is a robust and reliable modality for localizing epileptogenic zones and predicting surgical outcomes in DRE. Its complementary role alongside EEG, particularly in temporal lobe epilepsy, enhances surgical decision-making and supports a multimodal diagnostic approach for improved patient outcomes.