RESUMEN
The labeling of leukocytes with technetium-99m (Tc)-HMPAO is a frequent procedure in our laboratory, which was first validated before initiation of clinical studies with the commercial kit of Tc-D,L-hexamethylpropylene amine oxime (Tc-D,L-HMPAO), available from 1988. Recently, a new kit of exametazime has been introduced, with a similar composition and clinical indications, but with some technical improvements. Validation of the labeling procedure with this new kit is proposed, including a comparison between both commercial kits. Requirements for validation were achieved successfully and a comparative study showed no statistically significant differences; nevertheless, labeling of leukocytes may be expected routinely with the new kit on account of its longer shelf-life and lower cost.