A 67-year-old man with newly diagnosed multiple myeloma underwent both FDG and C-acetate PET/CT sequentially on different days. There was increased FDG activity only in L1 vertebral body, but there was diffuse abnormal C-acetate activity throughout the skeletal system. After the successful therapy, the patient who was on remission clinically underwent follow-up PET/CT scans. Interestingly, L1 remained to have elevated FDG, although with less intensity. In contrast, there was no abnormal C-acetate activity anywhere in the body. The patient remained in remission clinically.