Abstracts

RATIONALE: Region of interest analysis of fluoro-deoxyglucose (FDG)-PET images has been used to study inter-ictal glucose metabolism in temporal lobe epilepsy (TLE) patients. The ROI method is subjective since it requires a clear a priori hypothesis regarding the location of dysfunction. A group analysis using anatomic standardization, on the other hand, allows an objective method of FDG-PET analysis. Using this method, we compared inter-ictal glucose metabolism in medial TLE patients to a normal population (Minoshima et al. 1994). METHODS:Eighteen patients (11 left and 7 right) with medial TLE who are seizure free (>2 years) after anterior temporal lobectomy were included. Glucose metabolic imaging was performed with 10mCi (F-18)FDG during the resting inter-ictal state. Reconstructed tomographic images were transformed to the stereo-tactic atlas coordinates, followed by pixel normalization to global activity. Metabolic differences between 33 normal control subjects and TLE patients were compared on a pixel-by pixel basis using two sample t tests corrected for multiple pixel comparisons. RESULTS:Left TLE patients showed reduced ipsilateral glucose metabolism (p<.05) in the superior temporal gyrus (STG), middle temporal (MTG) and inferior temporal gyrus (ITG) (13%,13% and 12% respectively), anterior insula (9.7%) and superior frontal gyrus (9.7%). Right TLE patients showed reduced ipsilateral inter-ictal glucose metabolism (p<.05) in the ipsilateral STG (34%), MTG (12%), uncus (11.7%) and orbital gyrus (22%). CONCLUSIONS:Group analysis shows reduced inter-ictal glucose metabolism in the ipsilateral temporal neocortex, the insula, the orbito-frontal cortex and the superior frontal gyrus in unilateral medial TLE patients. This technique offers an objective method for identifying inter-ictal metabolic dysfunction in TLE patients, and studying its clinical correlates.