Comparison between F-18-FDG positron emission tomography and histology for the assessment of tumor necrosis rates in primary osteosarcoma.

BACKGROUND The purpose of this prospective study was to identify if F-18-fluorodeoxy-D-glucose positron emission tomography (F-18-FDG PET) was a reliable noninvasive surrogate of histologic response in determining the efficacy of neoadjuvant chemotherapy before surgical resection in primary osteosarcoma. METHODS Between January 2003 and December 2003, 10 patients with primary osteosarcomas were examined using F-18-FDG PET before neoadjuvant chemotherapy and surgery. The mean age at the time of first intervention was 19 years (range, 4-47 years). Positive prognostic significance was defined as more than 90% tumor necrosis response following neoadjuvant chemotherapy. The parameters of FDG uptake were correlated with histologic findings. The intraclass correlation coefficient was used to validate the tumor necrosis rates determined by PET and histology. RESULTS The tumor necrosis rate determined by PET was comparable with that determined histologically. The mean standardized uptake value before and following neoadjuvant chemotherapy were 8.2 and 4.4, respectively. The average tumor necrosis rate determined by PET was 22%. However, the mean tumor necrosis rate determined histologically was 54.5%. According to the intraclass correlation coefficient models, the intraclass correlation coefficient equaled O. The relationship of tumor necrosis rates determined by F-18-FDG PET and histology seems to be statistically insignificant. CONCLUSION In this preliminary study, FDG PET did not seem to be a promising tool for evaluating the response of primary osteosarcoma to neoadjuvant chemotherapy.