Evaluation of resting brain conditions measured by two different methods (i.v. and oral administration) with18F-FDG-PET

Abstract

Our aim was to evaluate regional differences between brain activity in two resting control conditions measured by 3D PET after administration of FDG through either the intravenous (i.v.) or the oral route. Ten healthy male volunteers 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 os. A set of 3D-PET scans (emission and transmission scans) were performed in both groups. To explore possible functional differences between the brains of the two groups, the SPM-96 software was used for statistical analysis. The results revealed that glucose metabolism was significantly higher in the superior frontal gyrus, superior parietal lobule, lingual gyrus and left cerebellar hemisphere in the i.v. group than in the oral group. Metabolically active areas were found in the superior, middle and inferior temporal gyrus, parahippocampal gyrus, amygdaloid nucleus, pons and cerebellum in the oral group when compared with the i.v. group. These differences were presumably induced by differences between FDG kinetics and/or time-weighted behavioral effects in the two studies. This study suggests the need for extreme caution when selecting a pooled control population for designated activation studies.

Human Radiation Dosimetry for Orally and Intravenously Administered 18F-FDG

“…Pain or stress may have effects on 18 F-FDG biodistribution that could be confounding. Masud et al showed quantitative differences in brain glucose metabolism between the oral and intravenous routes of 18 F-FDG administration (12). They observed glucose metabolism to be significantly higher in the superior frontal gyrus, superior parietal lobule, lingual gyrus, and left cerebellar hemisphere in the intravenous group than in the oral group.…”

“…They suggested performing radiation dosimetry studies, especially for gut and liver, before use in humans. Masud et al compared brain images obtained after intravenous and oral 18 F-FDG administration in healthy humans (12). The blood activity curve build-up phase after oral administration was slow and continued until around 110-120 min.…”