Comparison of PET Measurements of Cerebral Blood Flow and Glucose Metabolism for the Localization of Human Epileptic Foci

We compared the relative sensitivity of two interictal PET techniques, bolus injection of [15O] labeled water for estimation of cerebral blood flow (H2(15)O CBF-PET), and 18F 2-deoxyglucose (18FDG-PET) for cerebral glucose metabolism (CMRglc), and T2-weighted magnetic resonance imaging, in 28 patients with medically intractable complex partial seizures undergoing evaluation for surgery. There were statistically significant associations between lateralization by 18FDG-PET, and MRI, but not H2(15)O CBF-PET, and lateralization of the epileptic focus as defined by scalp-sphenoidal ictal EEG. Fifteen patients had surgery or subdural electrodes. 18FDG-PET was more closely associated with a good outcome than H2(15)O CBF-PET, which, in addition, showed hypoperfusion contralateral to the epileptic temporal lobe in several cases. H2(15)O sensitivity may have been reduced by technical factors, but 18FDG-PET appears to be more specific for localization of epileptic zones.