Associations Between Language Performance and Glucose Uptake Rate Using Dynamic FDG-PET in Focal Epilepsy
Abstract
Objective: Neuropsychological assessment and metabolic imaging inform presurgical planning for patients with focal epilepsy, but conventional static FDG-PET (sPET) has limitations in identifying disruptions in dominant hemisphere networks. Dynamic 2-[18F] fluoro-2-deoxy-D-glucose positron emission tomography (dFDG-PET) is a novel dynamic imaging technique that provides maps of glucose uptake rate (compared to traditional static standardized uptake value). This uptake rate may be a more sensitive measure of regional metabolism and may better characterize underlying language network disruption in patients with focal epilepsy undergoing presurgical evaluation. Method/Data Selection: This single-center prospective cohort study included epilepsy surgery candidates who underwent presurgical dFDG-PET and neuropsychological assessments (N=25). Glucose uptake rate was quantified as Z-scores across 36 brain regions (18 regions/hemisphere selected a priori based on relevance to cognitive domains assessed). Elastic Net regression identified regional glucose uptake rate and estimated strength of association to cognitive test performance, adjusting for patient age, IQ, and education. Results/Data Synthesis: Hypometabolic rates in the left frontal opercular Broca’s area (β=0.875) and left mesial temporal area (β=2.231) were associated with worse performance on phonemic fluency. Hypometabolism in the left temporal supramarginal area (β=0.687) and left mesial temporal area (β=0.638) were associated with worse performance on the Boston Naming Test. Conclusions: Language performance in focal epilepsy reflects disruption in dominant hemisphere language regions and extended regions, demonstrating that language dysfunction emerges from networks within and beyond dominant language structures. The novel technique of dFDG-PET identifies metabolically relevant regions associated with specific language functions, providing clinically meaningful information for presurgical epilepsy planning.