Evaluation of a simpler technique for in-vivo labelling of red blood cells with 99mTc

The efficiency of labelling red blood cells with intravenously administered 99mTcO4, by prior oral administration of stannous chloride dihydrate, has been evaluated. Optimum labelling occurred 1 hr after the oral dose of 200 mg of SnCl2.2 H2O and 20 min after the intravenous injection of 99mTcO4. The mechanism of labelling has been shown to be diffusion of 99Tc through the cell membrane followed by binding to haemoglobin in the presence of reducing agent. The in-vivo labelling technique has been found to be useful for the diagnosis of an abdominal mass and for static perfusion studies.