PET imaging of blood flow and glucose metabolism in localized musculoskeletal tumors of the extremities

IntroductionLittle is known about blood flow in sarcomas. Our purpose was to study glucose metabolism and blood flow in untreated localized musculoskeletal tumors of the extremities using [18F]fluorodeoxyglucose (FDG), oxygen-15 labeled water ([15O]H2O) and positron emission tomography (PET).MethodsSix patients with high-grade osteosarcoma (OS), two with soft-tissue sarcoma (STS) and one with aneurysmal bone cyst had PET studies with [15O]H2O and FDG. Arterial blood sampling and autoradiography calculation method were used to define blood flow as milliliters per 100 g times minutes. Tumor FDG uptake was measured as standardized uptake values (SUVs) and regional metabolic rates for FDG (rMRFDG). Two patients also had FDG PET studies during (one patient) and after (two patients) preoperative chemotherapy. All patients underwent dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The PET findings were compared with the clinical follow-up data and results of DCE-MRI.ResultsBlood flow in bone tumors was 31.7–75.2 ml/(100 g×min) and in STS 9.0–45.9 ml/(100 g×min). [18F]-Fluorodeoxyglucose uptake and rMRFDG in untreated bone tumors were 5.4–18.4 and 10.9–57.4 μmol/100 g/min, respectively. [18F]-Fluorodeoxyglucose uptake and rMRFDG in STS were 2.6–11.5 and 5.6–32.2 μmol/100 g/min, respectively. Four of five sarcomas with SUV>9.0 have already relapsed. High blood flow in untreated OS was related to long overall survival, while the predictive power of glucose metabolism was less apparent. Good histopathological response to therapy was not associated with long survival.ConclusionsMeasurement of blood flow in musculoskeletal tumors appears to be feasible by PET and [15O]H2O. The influence of tumor blood flow and glucose metabolism on the final outcome in sarcoma is variable and needs further research.