Accumulation of⁶⁴Cu-daratumumab in patients preadministered 45 mg of unlabeled daratumumab. (A) Maximum intensity projections on day 1 and day 2 showing significant BM uptake in the 2 patients with systemic MM. (B) Calvarial, vertebral, and pelvic uptake of ⁶⁴Cu-daratumumab shown in coronal views of the PET/CT fused image. Color bars for the fused PET/CT images are shared between patient 7 and patient 8. (C-D) The patient with a solitary plasmacytoma had comparatively low levels of radiotracer in the marrow and enhanced activity in the circulation, as evident from the day 1 scan. Heterogeneous and elevated uptake of radiotracer in all 3 regions is seen in the first 2 patients when compared with the patient with solitary plasmacytoma.