Physiological uptake values of 18F-FDG in long bones of the lower extremity on PET/CT imaging.

ABSTRACT

INTRODUCTION: Fluorine-18 fluorodeoxyglucose (F-FDG) PET/computed tomography (CT) has proven to be a valuable imaging modality with high diagnostic accuracy for the detection of bone infections. However, the physiological uptake values for F-FDG in the long bones of the lower extremity have not been established yet. This hampers correct interpretation of a F-FDG-PET/CT scan. PURPOSE: The purpose of this study was to determine the physiological uptake values of F-FDG in the long bones of the lower extremities, including the femur and the tibia. PATIENTS AND METHODS: We retrospectively analyzed the F-FDG-PET/CT scan of 84 consecutive patients from our database. F-FDG uptake parameters included mean standardized uptake value (SUVmean) and maximum standardized uptake value (SUVmax). Both SUVs were determined in the diaphyseal region of the femur and the tibia. RESULTS: SUVmean for the femoral diaphysis was 0.46 [95% confidence interval (CI) 0.42-0.49] and SUVmax was 0.81 (95% CI 0.74-0.88). For the tibial diaphysis, SUVmean was 0.34 (95% CI 0.32-0.37) and SUVmax was 0.61 (95% CI 0.56-0.65). SUVmean and SUVmax of the femur were significantly higher than that of the tibia (both P<0.01). SUVs for men were not significantly different from that for women and did not discriminate between age classes. CONCLUSION: For a correct interpretation of the F-FDG-PET/CT scan, we have determined the F-FDG uptake values in the long bones of the femur and the tibia. A SUVmean less than 0.5 and a SUVmax less than 0.8 can be considered as normal bone, irrespective of sex or age.