Enhanced liver uptake of Tc-99m-labeled RBCs during gastrointestinal bleed scintigraphy using transfused RBCs compared with autologous RBCs.

A gastrointestinal bleeding study was performed on 2 occasions on a 91-year-old woman. The in vitro method of red blood cell labeling with Tc-99m was used. Both studies were negative. The first study showed normal activity in the heart, liver, and great vessels. The second study was performed using cells from donor packed cells infused the day of the study. Using the heart as the reference organ, the relative degree of liver uptake is normally 50% with labeled autologous blood. The authors found a relative degree of liver uptake greater than 90% using labeled transfused red blood cells.