Abstract：Objective: To evaluate the 18F-FLT and 18F-FDG uptake as an indicator of early tumor response after radiotherapy. Methods: 18F-FLT and 18F-FDG PET-CT imaging were performed before treatment, 24 h and 48 h after radiotherapy on Wistar rats bearing Walkar 256 tumor. Quantitative data were expressed as percent of injected dose per gram(%ID/g) and tumor to non-tumor radioactivity ratios(T/NT). Correlation between %ID/g and T/NT with proliferation index(Ki-67) were measured. Results: 18F-FLT uptake in tumor decreased early after radiotherapy(P<0.001), LI-Ki-67 decreased early after radiotherapy(P<0.001) compared with controls. 18F-FDG uptake in tumor not decreased significantly 24 h and 48 h after radiotherapy(P>0.05，P>0.01), 18F-FLT uptake was positively correlated with LI-Ki-67(r=0.889). 18F-FDG uptake was not positively correlated with LI-Ki-67(r=0.379). 18F-FLT and 18F-FDG uptakes(T/NT) were positively correlated with %ID/g(r=0.807 and 0.813, respectively). Conclusion: 18F-FLT uptake decreased early after radiotherapy, and the uptake correlated significantly with proliferation of tumor cells early after radiotherapy. 18F-FDG uptake decreased slightly. 18F-FLT is better than 18F-FDG for the assessment of changes of cell proliferation early after radiotherapy.
2013, Vol. 24 
