%0 Journal Article %A Chieko Murayama %A Norihiro Harada %A Takeharu Kakiuchi %A Dai Fukumoto %A Akemi Kamijo %A Akira T. Kawaguchi %A Hideo Tsukada %T Evaluation of d-18F-FMT, 18F-FDG, l-11C-MET, and 18F-FLT for Monitoring the Response of Tumors to Radiotherapy in Mice %D 2009 %R 10.2967/jnumed.108.057091 %J Journal of Nuclear Medicine %P 290-295 %V 50 %N 2 %X O-18F-fluoromethyl-d-tyrosine (d-18F-FMT) is a promising novel agent for tumor imaging by PET. The aim of this study was to evaluate the potential of d-18F-FMT and the other conventional ligands used for tumor imaging, namely, 18F-FDG, l-11C-methionine (l-11C-MET), and 3′-deoxy-3′-18F-fluorothymidine (18F-FLT), as a PET ligand for monitoring early responses to radiotherapy in tumor-bearing mice. Methods: C3H/HeN mice inoculated with murine squamous cell carcinomas were treated with a single dose of x-ray irradiation at 2, 6, 20, or 60 Gy. Tumor uptake of each ligand was examined 1, 3, and 7 d after the irradiation. Results: Tumor uptake of d-18F-FMT was decreased on day 1 after irradiation at 6, 20, or 60 Gy, and the decrease persisted until day 7. Tumor uptake of 18F-FDG was elevated on days 1 and 3 after irradiation at 2, 6, or 20 Gy, followed by a decrease in uptake on day 7 in mice irradiated at 20 or 60 Gy. Decreased tumor uptake of l-11C-MET was observed only on day 3 after the irradiation. Decreased tumor uptake of 18F-FLT was detected on day 1 after irradiation at 2, 6, 20, or 60 Gy; thereafter, the dose-dependent decrease in uptake was no longer seen. Only for d-18F-FMT were significant positive correlations found between ligand uptake at all the time points examined and tumor volume on day 14 after various doses of irradiation. Conclusion: The findings suggest that d-18F-FMT is a promising PET ligand for early-phase detection and prediction of the effects of radiation therapy. %U https://jnm.snmjournals.org/content/jnumed/50/2/290.full.pdf