Comparison of ¹⁸F-sodium fluoride uptake in the whole bone, pelvis, and femoral neck of multiple myeloma patients before and after high-dose therapy and conventional-dose chemotherapy

Aim: To compare the effects of high-dose therapy (HDT consisting of high-dose chemotherapy followed by autologous stem cell transplantation) and conventional-dose chemotherapy (non-HDT) on the uptake of ¹⁸F-sodium fluoride (NaF) in the whole bone, pelvis, and femoral neck of multiple myeloma (MM) patients.

Method: The data of 19 MM patients who received HDT (61.5 (SD 5.6) years) and 11 MM patients who received conventional-dose chemotherapy (70.9 (SD 7.2) years) were collected in a prospective study. NaF PET/CT imaging was performed at baseline, and 8 weeks and 2 weeks after treatment for the HDT group and the non-HDT group, respectively. A CT-based algorithm was applied to segment the bones, and the global mean SUV (GSUVmean) of the whole bone and pelvis was calculated (OsiriX MD v.9.0, Pixmeo SARL; Bernex, Switzerland). In addition, regions of interest for the whole, medial, and lateral femoral neck were delineated bilaterally. Whole bone and pelvis measurements were replicated by two observers.

Results: The average GSUVmean in the whole bone and pelvis of the patients who underwent HDT significantly decreased from before to after treatment (- 16.27%, p = 0.02 and - 16.54%, p = 0.01, respectively). A significant decrease in the whole and lateral femoral neck was also observed bilaterally in the HDT group. No significant decrease in average GSUVmean was observed in the non-HDT group. A high level of inter-observer reliability was found in intra-class correlation (ICC for pre-treatment whole bone 0.983, post-treatment whole bone 0.989, pre-treatment whole pelvis 0.998, post-treatment whole pelvis 0.996).

Conclusion: NaF uptake significantly decreased after treatment in patients who received high-dose therapy. A high level of agreement was observed between two operators for whole bone and pelvis measurements.