A comparative study of Tc-99(m)-d,l-HMPAO and Tc-99(m)-d,l-CBPAO as leukocyte-labelling agents

An attempt was made to use Tc-99(m)-d,l-cyclobutylpropylene amine oxime (Tc-99(m)-d,l-CBPAO) to label leukocytes. The radiochemical purity of Tc-99(m)-d,l-CBPAO, labelling efficiency of leukocytes, cell viability of labelled leukocytes and stability of Tc-99(m)-d,l-CBPAO-labelled leukocytes were calculated. In comparison with the commercial cell-labelling agent Tc-99(m)-d,l-hexamethylpropylene amine oxime (Tc-99(m)-d,l-HMPAO), (1) the radiochemical purity of Tc-99(m)-d,l-CBPAO was higher than that of Tc-99(m)-d,l-HMPAO immediately after and 1, 2, 4, 6, 8 and 24 h after Tc-99(m) labelling; (2) the labelling efficiency of Tc-99(m)-d,l-CBPAO-labelled leukocytes was lower than that of Tc-99(m)-d,l-HMPAO; (3) the viability of labelled white blood cells was high for both agents; and (4) the stability of Tc-99(m)-d,l-CBPAO-labeIled leukocytes was better than that of Tc-99(m)-d,l-HMPAO after 1, 2, 4, 6, 8 and 24 h. In conclusion, although the labelling efficiency of Tc-99(m)-d,l-CBPAO is lower, it is more stable than Tc-99(m)-d,l-HMPAO and provides greater stability of Tc-99(m)-d,l-CBPAO-labeIled leukocytes. Therefore, Tc-99(m)-d,l-CBPAO has the potential to replace Tc-99(m)-d,l-HMPAO as a commercial leukocyte-labelling agent.