A basic study showed that the intracellular uptake of 18F-FET in a myeloma cell line was lower than that of 18F-FDG and 11C-MET and that the amount of 18F-FET retained by CD138+ plasma cells tended to be less than that of 18F-FDG and 11C-MET (23). Here, SDC1 is linked to plasma cell myeloma.