AN ANIMAL-MODEL FOR INVIVO EVALUATION OF TUMOR GLYCOLYTIC RATES WITH POSITRON EMISSION TOMOGRAPHY

We developed a method for evaluating tumor glycolytic rates in vivo wi th nude mice injected with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) and a dedicated animal positron emission tomography (PET) scanner. Animals were injected with NR-6 mouse fibroblast tumor cell lines. When tumor s achieved a large enough size to be macroscopically visible, quantita tive measurements of FDG uptake in vivo were obtained, using both stan dard nonlinear regression with the FDG tracer kinetic model to generat e estimates of model parameters, including K(NLR), the rate constant f or net phosphorylation of FDG. Additionally, we determined the values of K(PAT), the rate constant for net phosphorylation of FDG measured w ith a non-iterative graphical method. Estimates of K were highly corre lated (r = 0.95) with both methods, and parametric images of K(PAT) de monstrate both the tumor location and size, but are also scaled in uni ts of phosphorylation of FDG. The method is suitable for serial studie s of tumor glucose metabolism during and after therapeutic interventio ns, such as chemotherapeutic trials.