Technical considerations in labeling of blood elements.

The technical difficulties of labeling albumin, red blood cells, white blood cells, and platelets are discussed with respect to the effect of procedual differences on the in vivo fate of the radiolabeled blood element. Albumin can be labeled with 99mTc by a variety of procedures that have not been proved clinically. The labeling of erythrocytes with 51Cr is well defined, but the demand for a better radionuclide has not led to a routine procedure for 99mTc-labeled red blood cells. The procedure for labeling white blood cells and platelets with 51Cr has been established, but the in vivo viability of the cells remains in question. Labeling techniques with other isotopes such as 67Ga and 99mTc are still being developed. Blood elements labeled with 51Cr are by far the best defined species, but much remains to be done with isotopes having better physical properties.