Quantification of F-18FDG PET images in temporal lobe epilepsy patients using probabilistic brain atlas

A probabilistic atlas of the human brain (Statistical Probabilistic Anatomi cal Maps: SPAM) was developed by the international consortium for brain map ping (ICBM). It is a good frame for calculating volume of interest (VOI) in many fields of brain images. After calculating the counts in VOI using the product of probability of SPAM images and counts in FDG images, asymmetric indices (AI) were calculated and used for finding epileptogenic zones in m esial temporal lobe epilepsy (mTLE), FDG PET images from 18 surgically conf irmed mTLE patients and 22 age-matched controls were spatially normalized t o the average brain MRI template of ICBM. Counts from normalized PET images were multiplied with the probability of 12 VOIs from SPAM images in both t emporal lobes. Finally AI were calculated on each pair of VOIs, and compare d with visual assessment. If AI of mTLE patients were not within 2.9 standa rd deviation from those of normal control group (P < 0.008; Bonferroni corr ection for P < 0.05), epileptogenic zones were considered to be found succe ssfully The counts of VOIs in the normal control group were symmetric (AI < 4.3%, paired t test P > 0.05) except for those of the inferior temporal gy rus (P < 0.001). By AIs in six pairs of VOIs, PET in mTLE had deficit on on e side (P < 0.05). Lateralization was correct in only 14/18 of patients by AI, but 17/18 were consistent with visual inspection. In three patients wit h normal Al, PET images were symmetric on visual inspection. The asymmetric indices obtained by taking the product of the statistical probability anat omical map and FDG PET, correlated well with visual assessment in mTLE pati ents. SPAM is useful for the quantification of VOIs in functional images. ( C) 2001 Academic Press.