Background : The most reliable standard method for the in vivo RBC survival test
was known to be the radioisotope labelling method, especially by using the radioisotope
51 Cr and 111 In. But, these methods had some limitations
such as high cost and difficulties in time supply. The utility of 99m
Tc-labelled RBCs with SnCl 2 was introduced as an alterative and
attempted here to prove to be able to give stable reliable results of the transfused RBC
survival.
Materials and Methods : Approximately 10mL of packed RBCs of fess than 7 days old
autologous and heterologous bloods were labelled with 99m Tc and stanous
fluoride(Amersham, USA), and were incubated at 37℃ for 30 minutes, and aseptically
washed 3 times with isotonic saline, and then were injected to the autologous(n=5) and
heterologous(n=3) volunteers. After 3, 10, 15, 20, 30 minutes and 1, 2, 24 hours, the
venous blood samples were collected from the above volunteers, and their radioactivities
were counted by the Gamma-counter(Cobra II, Germany).
Results : The mean 24 hour survival rate of the 99mTc-labelled RBCs
was 76.6% in the autologous transfused group and 74.2% in the heterologous group. The
mean labelling efficiency of 99mTc-labelled RBCs was 95.2%(n=4). The
viabilityassaybetween thetrans-fused 51Crand
99m Tc-labelled same RBCs showed a strong correlation (r=0.82, P=0.024).
Conclusion: The 51Tc-labelled RBC showed high labelling efficiencies
and reliable post-transfusional viability(over 70%)compared to the
51 Cr-labelling RBCs. Subsequently, 99m Tc-labelling method
is one of the alterative to replace the 51 Cr-labelling method.

Keywords: 99m Tc, Viability, Transfusion