[Inhibition of 18F-FDG uptake in glioblastoma cells by FDG and glucose]

It was the aim of the study to compare the inhibition of 18F-2-Fluor-D-deoxy-glucose uptake (18F-FDG) in tumor cells by various concentrations of FDG carrier or D-glucose in an experimental model using tissue culture and positron emission tomography (PET). Glioblastoma cells in culture were incubated with 18F-FDG with and without added carrier or in presence of glucose concentrations in the range from 0-5 mmol/L. Cellular uptake of 18F-FDG was measured after 20 min. of incubation in PBS-buffer containing different sugar concentrations. The uptake was determined with a PET camera. The similarity of the kinetics of the FDG and glucose uptake are backing the hypothesis that both substrates use the same carrier system. The more intense inhibition of the 18F-uptake by FDG can be explained by the different intracellular metabolism of both substrates. The results explain the clinical experience that there is an optimal 18F-FDG uptake in the patient's tumor when the blood glucose level is as low as possible and the specific activity of 18F-FDG is very high.