Statistically driven identification of focal metabolic abnormalities in temporal lobe epilepsy with corrections for tissue heterogeneity using H-1 spectroscopic imaging

H-1 spectroscopic imaging of N-acetyl-aspartate, creatine, and choline has proven to be a sensitive indicator for the lateralization of seizure foci i n temporal lobe epilepsy. Previous studies have used right-left comparisons to identify the epileptogenic tissue assuming that alterations due to the disease process outweigh the effects of tissue heterogeneity. To evaluate t he effectiveness of tissue heterogeneity corrected analyses, we evaluated t hree criteria for lateralization of the seizure focus: 1) a statistically d riven method adjusted for tissue composition, 2) a single valued threshold, and 3) a single global index of the hippocampus. The statistically driven analysis lateralized all eight patients correctly, whereas the single thres hold method incorrectly lateralized one case and the global index failed to identify a significant difference in two cases. These findings indicate th at increased accuracy and sensitivity can be obtained by correcting for tis sue heterogeneity when analyzing spectroscopy studies of temporal lobe epil epsy. (C) 2000 Wiley-Liss, Inc.