Improved Modification for In Vitro Labeling of Red Blood Cells with Technetium-99m

We have tested a modification of the Brookhaven method for in vitro labeling of red blood cells (RBCs) with technetium-99m by adding an initial centrifugation step and performing the labeling on packed RBCs. This results in reproducible, high labeling efficiencies (99.3% ± 0.4%, n =50) after 15 min of incubation. The use of packed RBCs also results in a higher concentration of labeled RBCs (smaller bolus for injection) and less radiation exposure to the technologist. This technique has proved useful for radio nuclide angiography, venography, gastrointestinal bleeding studies, and red cell mass determinations. It is parlicularly advantageous for RBC labeling in patients receiving chemotherapy.