Evaluation of radionuclide therapy for the palliation of bone metastasis pain using 89Sr: Comparison of SUV values of bone metastases measured by 99mTc bone SPECT, 18F-fluoride PET/CT, and 18F-FDG PET/CT

2029 Objectives: 99mTc bone scintigraphy, 18F-fluoride (NaF) PET/CT, and 18F-FDG PET/CT are used for diagnosing bone metastasis. In this study, we calculated standardized uptake values (SUVs) of bone metastases by 99mTc bone SPECT, 18F-NaF PET/CT, and 18F-FDG PET/CT in order to quantitatively evaluate the efficacy of 89Sr therapy. Methods: Our study subjects were 9 patients with a total of 92 bone metastases, diagnosed by 99mTc bone scintigraphy, 18F-NaF PET/CT, and 18F-FDG PET/CT, who underwent 89Sr therapy for the palliation of pain from bone metastases. We manually set the volume of interest for each metastasis using the quantitative analysis software GI-BONE and GI-PET (AZE, Japan), and measured SUVmax and SUVpeak using 99mTc bone SPECT, 18F-NaF PET/CT, and 18F-FDG PET/CT. We defined the metastases with an SUV that increased by at least 0.8 (30%) as “progressed,” and the rest as “non-progressed.” We calculated the proportion of cases in which the results of evaluations by 99mTc bone SPECT, 18F-NaF PET/CT, and 18F-FDG PET/CT were consistent. Results: Most bone metastases were evaluated as “non-progressed” by 99mTc bone SPECT, 18F-NaF PET/CT, and 18F-FDG PET/CT. The rate of consistency when SUVmax was used was 84/92 (91.3%) and that when SUVpeak was used was 80/92 (87.0%). Among the bone metastases that did not match, there were instances in which the evaluation according to 99mTc bone SPECT and 18F-NaF PET/CT was “non-progressed”, but that according to 18F-FDG PET/CT was “progressed”. We observed an improvement in clinical symptoms in all study subjects. Discussion and Conclusions: When we categorized the bone metastases into “progressed” and “non-progressed” according to SUVs before and after treatment, the evaluations according to 99mTc bone SPECT, 18F-NaF PET/CT, and 18F-FDG PET/CT largely matched to each other, and most cases of bone metastases were categorized into “non-progressed” group. The results of evaluation depending upon SUV were largely consistent with the results of clinical evaluation: clinical symptoms were improved by the treatment in all study subjects. The bone metastases with an increased SUV according to 18F-FDG PET/CT after treatment seemed to have a higher level of activity than the other bone metastases. There was a minimal difference in evaluations according to SUVmax and SUVpeak.