Prospective Comparison of 11C-4DST, 18F-FDG PET/CT and whole-body MRI in the patients with multiple myeloma

1610 Objectives 49-[methyl-11C]-thiothymidine (4DST) has been developed as an in vivo cell proliferation marker based on its DNA incorporation mechanism. We prospectively evaluated 4DST PET/CT in the patients with multiple myeloma (MM), and compared the result to FDG PET/CT and whole-body MRI (WBMRI). Methods 21 patients (Male 14, Female 7, mean age 62) were referred to our hospital with suspicion of MM. 4DST, FDG PET/CT and WBMRI (T1WI and short tau inversion recovery image) were performed for the detection of MM lesions. 4DST and FDG PET/CT image were visually evaluated by the two board certified nuclear medicine physicians, and WBMRI images were evaluated by two board certified radiologists. Agreement was reached by consensus. A direct comparison for each detected lesion was performed among the 3 scans by one of the investigators. Reference standard was the result of bone marrow biopsy. Results Of 21 enrolled patients, 14 patients were histologically proved MM (heavy chain component: IgG 7, IgA 3, solitary plasmacytoma 2, MGUS 1, IgG with BJP 1) and 7 patients were negative. The sensitivity, specificity, PPV, NPV and accuracy of 4DST PET/CT was 79%, 86%, 92%, 67% and 81%, respectively, those of FDG PET/CT was 71%, 100%, 100%, 64% and 81%, respectively, and those of WBMRI were 64%, 100%, 100%, 58% and 76%, respectively. 4DST PET/CT (79%) showed higher sensitivity than FDG PET/CT (71%) and WBMRI (64%) for the detection of MM lesion. When 4DST PET was combined with WBMRI, the sensitivity was 100% which was higher than the combination of FDG PET and WBMRI (79%). Conclusions 4DST PET/CT is superior to FDGPET/CT and WBMRI for evaluation of MM. Moreover combined 4DST PET and WBMRI may have great potential of changing the management of patients with MM.