Characterization of Bone Lesions in Myeloma Before and During Anticancer Therapy Using F-FDG-PET/CT and F-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-fluoro-2-deoxy-D-glucose (F-FDG)-PET/CT and F-sodium fluoride (F-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-FDG and with F-NaF, both at baseline and after treatment. All patients had positive scans. Volumes of interest (VOIs) were drawn over all F-FDG-PET/CT-positive bone lesions, as well as the corresponding regions in F-NaF-PET/CT. For characterization of bone lesions, semi-quantitative standard uptake value (SUV) parameters were measured.

Results: F-FDG-PET/CT in the seven patients detected 39 metabolically active lesions that were correlated with the corresponding sites in F-fluoride-PET/CT. Overall, the lesions showed a response to therapy, with a significant decrease in SUV on PET/CT using F-FDG (p<0.001) and with F-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.