Characterization of Bone Lesions in Myeloma Before and During Anticancer Therapy Using 18F-FDG-PET/CT and 18F-NaF-PET/CT

Background: The objective of this study was to characterize tumor activity and mineralization status in newly-detected multiple myeloma (MM) bone lesions using 2-F-18-fluoro-2-deoxy-D-glucose (F-18-FDG)-PET/CT and F-18-sodium fluoride (F-18-NaF)-PET/CT before and after antitumor treatment. Materials and Methods: In this retrospective study, seven patients with histologically-verified MM were included (four women, three men; median age=57 years, standard deviation=11.23 years). PET/CT was performed with F-18-FDG and with F-18-NaF, both at baseline and after treatment. All patients had positive scans. Volumes of interest (VOIs) were drawn over all F-18-FDG-PET/CT-positive bone lesions, as well as the corresponding regions in F-18-NaF-PET/CT. For characterization of bone lesions, semi-quantitative standard uptake value (SUV) parameters were measured. Results: F-18-FDG-PET/CT in the seven patients detected 39 metabolically active lesions that were correlated with the corresponding sites in F-18-fluoride-PET/CT. Overall, the lesions showed a response to therapy, with a significant decrease in SUVmax on PET/CT using F-18-FDG (p< 0.001) and with F-18-NaF (p< 0.001). In four patients with a second follow-up scan (at a median of 17 months after baseline scan), there was no significant change in lesion uptake. Conclusion: Based on our data, antitumor therapy in MM reduces not only tumor activity, but also the mineralization status of bone lesions. A second follow-up scan in a subset of the cohort yielded no change in mineralization status.