An Evaluation of 2-deoxy-2-[18F]Fluoro-D-Glucose and 3'-deoxy-3'-[18F]-Fluorothymidine Uptake in Human Tumor Xenograft Models

The aim of this study is to assess the variability of 2-deoxy-2-[F-18]fluoro--glucose ([F-18]-FDG) and 3'-deoxy-3'-[F-18]-fluorothymidine ([F-18]-FLT) uptake in pre-clinical tumor models and examine the relationship between imaging data and related histological biomarkers. [F-18]-FDG and [F-18]-FLT studies were carried out in nine human tumor xenograft models in mice. A selection of the models underwent histological analysis for endpoints relevant to radiotracer uptake. Comparisons were made between uptake, imaging, and histopathology data using quantitative and semi-quantitative analysis. data revealed that [1-C-14]-2-deoxy--glucose ([C-14]-2DG) uptake in the tumor cell lines was variable. , [F-18]-FDG and [F-18]-FLT uptake was highly variable across tumor types and uptake of one tracer was not predictive for the other. [C-14]-2DG uptake did not predict for [F-18]-FDG uptake . [F-18]-FDG SUV was inversely proportional to Ki67 and necrosis levels and positively correlated with HKI. [F-18]-FLT uptake positively correlated with Ki67 and TK1. When evaluating imaging biomarkers in response to therapy, the choice of tumor model should take into account baseline radiotracer uptake, which can vary significantly between models.