Effect of Sn(II) ion concentration and heparin on technetium-99m red blood cell labeling

While convenience and economy favor the use of in vivo methods for labeling red blood cells (RBCs) with [99mTc]pertechnetate, previous reports suggested that patient medication such as heparin might interfere and thus result in inferior quality images. In this study, using a canine model, the role of stannous Sn(II) ion in in vivo and in vitro labeling of RBCs both in the presence and absence of a therapeutic dose of heparin was investigated. Our results showed that Sn(II) ion concentration of 20 micrograms/kg body weight levels provided better than 80% in vivo labeling efficiency enabling high quality blood-pool images even in the presence of therapeutic doses of heparin.