Tin level requirements for multiple gated studies in humans: A new perspective

Stannous pyrophosphate (Sn-PYP) has been used for over a decade for in vivo and in vitro labeling of red blood cells with 99mTc. Literature references indicate minimum levels of stannous ion [Sn(II)] acceptable for successful labeling, based on in vitro experiments, to range from 140 to 400 ng/mL of whole blood. Our study was undertaken in 200 patients using two different commercially available formulations of Sn-PYP in order to quantitate the Sn(II) levels required on an in vivo basis to achieve consistently high quality labeling.