Visualisation of neuroblastoma growth in a Scid mouse model using [18F]FDG and [18F]FLT-PET

Background: Tumor therapy has been monitored using the metabolic indicator [F-18]fluorodeoxyglucose ([F-18]FDG). However, the nucleotide precursor [F-18]fluoro-thymidine ([F-18]FLT) is in principle more specific as it is incorporated into DNA. Thus, the [F-18]FDG and [F-18]FLT uptake by human neuroblastomas grown in Scid mice are compared in this study. Materials and Methods: Scid mice were inoculated with human neuroblastoma cells. Tumor imaging was performed with a human whole-bodyfull-ring PET scanner. Furthermore, the tumor weight and the cell proliferation rate were determined. Results: Neuroblastomas could be visualised using [F-18]FDG in 40% and with [F-18]FLT in 70% of the cases. [F-18]FDG or [F-18]FLT uptake could not be visualised in neuroblastomas less than 1.0 g in weight. No correlation between the cell proliferation rate and tracer uptake could be detected. Conclusion: [F-18]FLT showed a higher uptake than [F-18]FDG and, therefore, might be more suitable for monitoring anticancer therapy, at least in this tumor model.