18F-Fluoride PET/CT for detection of bone metastasis in patients with renal cell carcinoma: a pilot study

PurposeThe aim of this study was to evaluate the role of F-18-fluoride PET/computed tomography (CT) in the detection of bone metastasis in patients with renal cell carcinoma (RCC) and compare the results with fluorine-18 fluorodeoxyglucose (F-18-FDG) PET/CT and technetium-99m methylene diphosphonate bone scintigraphy (BS) when available.Materials and methodsThe data of 36 patients (mean age: 52.514.1 years; male/female: 27/9) with RCC who prospectively underwent F-18-fluoride PET/CT were analyzed. PET/CT images were analyzed by two nuclear medicine physicians in consensus, visually and semiquantitatively [maximum standardized uptake value (SUVmax)]. Results of F-18-fluoride PET/CT were compared with those of F-18-FDG PET/CT (n=16) and BS (n=22). Histopathology or clinical or imaging follow-up (minimum 6 months) were used as the reference standard.ResultsOverall, F-18-fluoride PET/CT showed a sensitivity of 100%, specificity of 94.4%, positive predictive value of 94.7%, negative predictive value of 100%, and accuracy of 97.2%. It demonstrated a total of 134 skeletal lesions, of which 101 were characterized as metastasis and 33 as benign. Corresponding CT changes were seen for 129/134 lesions. The mean SUVmax of the lesions was 30.3 +/- 48.4. F-18-Fluoride PET/CT and F-18-FDG PET/CT showed similar accuracy for visualization of bone metastasis (93.7 vs. 100%; P=0.993). However, F-18-FDG PET/CT additionally demonstrated extraskeletal metastasis in 6/16 patients. No significant difference was seen between the accuracies of BS and F-18-fluoride PET/CT for visualization of bone metastasis (93.7 vs. 100%; P=0.115), but the former showed significantly more skeletal lesions (91 vs. 44; P<0.0001). In 4/22 patients (18%) with negative BS, F-18-fluoride PET/CT demonstrated skeletal metastasis.Conclusion(18)F-Fluoride PET/CT shows high diagnostic accuracy for the detection of bone metastasis in patients with RCC. It shows comparable results to F-18-FDG PET/CT and detects more skeletal lesions compared to BS.