18F-FDG, 11C-Methionine, and 68Ga-Pentixafor PET/CT in Patients with Smoldering Multiple Myeloma: Imaging Pattern and Clinical Features

This study aimed to explore the correlation between imaging patterns and clinical features in patients with smoldering multiple myeloma (SMM) who simultaneously underwent 18F-FDG, 11C-Methionine, and 68Ga-Pentixafor positron emission tomography/computed tomography (PET/CT). We retrieved and analyzed clinical characteristics and PET imaging data of 10 patients with SMM. We found a significant correlation between bone marrow (BM) plasma cell (PC) infiltration and mean standardized uptake values (SUVmean) of lumbar vertebrae L2-L4 on 11C-Methionine PET/CT scans (r= 0.676,p= 0.031) and 68Ga-Pentixafor PET/CT scans (r= 0.839,p= 0.002). However, there was no significant correlation between BM involvement and SUV(mean)of lumbar vertebrae L2-L4 on 18F-FDG PET/CT scans (r= 0.558,p= 0.093). Similarly, mean target-to-background ratios (TBRmean) of lumbar vertebrae L2-L4 also correlated with bone marrow plasma cell (BMPC) infiltration in 11C-Methionine PET/CT (r= 0.789,p= 0.007) and 68Ga-Pentixafor PET/CT (r= 0.724,p= 0.018) PET/CT. In contrast, we did not observe a significant correlation between BMPC infiltration rate and TBR(mean)in 18F-FDG PET/CT (r= 0.355,p= 0.313). Additionally, on 11C-Methionine PET/CT scans, we found a significant correlation between BMPC infiltration and TBR(max)of lumbar vertebrae L2-L4 (r= 0.642,p= 0.045). In conclusion, 11C-Methionine and 68Ga-Pentixafor PET/CT demonstrate higher sensitivity than 18F-FDG PET/CT in detecting BM involvement in SMM.