Comparison of⁶⁴Cu-daratumumab with¹⁸F-FDG. (A-B) Maximum intensity projections comparing the uptake of ⁶⁴Cu-daratumumab with ¹⁸F-FDG. Similar skeletal uptake in the right humerus for both tracers was observed (red rectangles) in patient 1 (A), while ⁶⁴Cu-daratumumab, but not ¹⁸F-FDG uptake in the femur and fibula (SUV_max 3.3), was observed in patient 7 (B). (C) Sagittal cross-section through scans comparing ⁶⁴Cu-daratumumab and ¹⁸F-FDG uptake in 2 regions (sternum and pelvis, red arrows) found positive for MM infiltration by biopsy. (D) Heterogeneous pelvis uptake of ⁶⁴Cu-daratumumab in the region that was found positive for MM by biopsy (red arrow), but negative by ¹⁸F-FDG. (E) Biopsy acquired (red arrow) from patient 2 with right clavicular uptake on ¹⁸F-FDG but not on ⁶⁴Cu-daratumumab, which was negative for MM infiltration upon biopsy. (F) Sagittal cross-section through scans comparing ⁶⁴Cu-daratumumab and ¹⁸F-FDG uptake in another patient showing elevated ¹⁸F-FDG and no ⁶⁴Cu-daratumumab uptake in the pleural-based mass, a region indicated to be myeloma-negative by biopsy. (G) Prominent calvarial uptake (yellow arrows) around bone lesions was seen in the ⁶⁴Cu-daratumumab PET images of patient 1, which is typically obscured by the brain uptake of ¹⁸F-FDG. Color bars are shared between the ¹⁸F-FDG PET and ⁶⁴Cu-DOTA–daratumumab PET images when 1 color bar is grouped with a pair of images.