2626 18F-FDG-PET Hypometabolism As a Predictor of Surgical Outcome for Drug Resistant Focal Epilepsy: a Systematic Review and Meta-Analysis

Objectives18F-FDG-PET is commonly used in the pre-surgical evaluation of patients with drug-resistant epilepsy, however, the prognostic value of the detection of focal hypometabolism is uncertain and previous meta-analyses have been negative. We conducted a systematic review and meta-analysis to examine whether localisation with 18F-FDG-PET hypometabolism predicts favourable outcome in epilepsy surgery.MethodsA systematic literature search of Embase, Medline and Web of Science was undertaken for publications that included evaluation with 18F-FDG-PET prior epilepsy surgery, and which reported surgical outcome at ≥12 months. Random effects meta-analysis was used to calculate the proportion of patients achieving a favourable (Engel class I, ILAE class 1–2, or seizure-free) outcome. Sources of heterogeneity were investigated using meta-regression.ResultsThe database search identified 12917 studies. Of these, 101 studies (4067 patients in total) were included. A favourable outcome was achieved in 77% patients with localising 18F-FDG-PET hypometabolism, compared to 53.5% patients without localising hypometabolism. Focal hypometabolism within a single epileptogenic lobe was associated with a higher chance of favourable outcome (82.6%) compared to regional hypometabolism (the epileptogenic lobe and an additional adjacent lobe, 61.8%) or diffuse hypometabolism (extending beyond 2 adjacent lobes, 54.5%). Concordance of 18F-FDG-PET with ictal scalp EEG (76.8% vs 59.8%) and MRI (78.9% vs 60.9%) were also associated with higher chances of a favourable outcome compared to non-concordance.ConclusionLocalising 18F-FDG-PET hypometabolism predicts favourable outcome at ≥12 months following epilepsy surgery. Focal hypometabolism and concordance with MRI and ictal scalp EEG findings are additional factors that are associated with favourable outcome.