A pilot study in epilepsy patients using simultaneous PET/MR.

Integrated PET/MR with simultaneous acquisition may improve the identification of pathologic findings in patients. This pilot study evaluated metabolic activity differences between epilepsy patients and healthy controls and directly correlated FDG uptake with MR regional abnormality. Epilepsy patients (n=11) and controls (n=6) were imaged on a whole-body simultaneous PET/MR scanner. After FDG injection, simultaneous images were acquired for 60 minutes. Statistical analyses on SUV values (over 117 brain regions, including left and right, for 96 cortical and 21 subcortical regions) derived from three normalization methods, by individual subject's mean cortical, white matter or global brain, were compared between groups. The asymmetry was compared. T2, T1 and PET co-registered images were also used for lesion detection and correlation of PET and MR regional abnormality. Left and right postcentral gyri were found to be consistently hypermetabolic regions, while right temporal pole and planum polare were consistently hypometabolic regions by all three normalization methods. Using the asymmetry index (AI > 10% or SUV ratios > 1.2), more metabolic asymmetry regions were detected in patients than in controls, with 96.2% agreement. The presence of hippocampal abnormalities or cortical tubers detected via T2 FLAIR in patients correlated well with the hypometabolism detected via FDG-PET. Our results showed specific patterns of metabolic abnormality and asymmetry over 117 brain regions in epilepsy patients, as compared to controls, suggest that simultaneous PET/MR imaging provides a useful tool to help understand etiopathogenesis and localize seizure foci.