Evaluation of resting brain conditions measured by two different methods (i.v. and oral administration) with F-18-FDG-PET

Our aim was to evaluate regional differences between brain activity in two resting control conditions measured by 3D PET after administration of FDG t hrough either the intravenous (i.v.) or the oral route. Ten healthy male vo lunteers engaged in the study as the i.v. group (mean age, 26 +/- 9.3 years , +/- S.D.) who received FDG intravenously and another 10 volunteers as the oral group (mean age, 27.9 +/-11.3 years, +/- S.D.) who received FDG per o s. A set of 3D-PET scans (emission and transmission scans) were performed i n both groups. To explore possible functional differences between the brain s of the two groups, the SPM-96 software was used for statistical analysis. The results revealed that glucose metabolism was significantly higher in t he superior frontal gyrus, superior parietal lobule, lingual gyrus and left cerebellar hemisphere in the i.v. group than in the oral group. Metabolica lly active areas were found in the superior, middle and inferior temporal g yrus, parahippocampal gyrus, amygdaloid nucleus, pens and cerebellum in the oral group when compared with the i.v. group. These differences were presu mably induced by differences between FDG kinetics and/or time-weighted beha vioral effects in the two studies. This study suggests the need for extreme caution when selecting a pooled control population for designated activati on studies.