Abstract:Objective: To evaluate potential role of 18F-fluoro-2-deoxy-D-glucose(18F-FDG) in assessing chemotherapy response of primary osteosarcoma. Methods: Seven patients with osteosarcoma confirmed by pathology were examined with 18F-FDG imaging before and after chemotherapy. Two practiced nuclear medicine doctor observed the image and do the semi-quantitative analysis. Tumor to non-tumor radioactivity count ratios(TNR) was used. The radioactivity count variance ratio before and after chemotherapy obtained by using formula(TNR1-TNR2)/TNR1. The histopathological tumor necrosis were obtained by surgery. Result: The radioactivity count before and after chemotherapy(TNR1max and TNR2max;TNR1average and TNR2average) had significant difference(P<0.05). Four of the 7 patients got histopathological tumor necrosis, which had a significant correlation to the radioactivity count variance ratio. The correlation coefficient of (TNR1-TNR2)/TNR1max and (TNR1-TNR2)/TNR1average with the tumor necrosis were 0.94 and 0.84 respectively. Conclusion: 18F-FDG imaging can be used to assess the chemotherapy response of osteosarcoma noninvasively.The semi-quantitative analysis which has consistency with the histopathological tumor necrosis is helpful in evaluating response of osteosarcoma to chemotherapy.