In vitro evaluation of white blood cell labelling with 99Tcm radiopharmaceuticals

Several commercially available 99Tcm radiopharmaceuticals were tested as possible white blood cell labelling agents. Labelling efficiency, labelling stability and white blood cell adherence were measured in vitro. White blood cells were not successfully labelled with mebrofenin, disofenin, gluceptate or dimercaptosuccinic acid but were successfully labelled with exametazime, albumin colloid, sulphur colloid, sestamibi and teboroxime. Exametazime had the highest mean labelling efficiency of 79%. Labelling efficiency was 5-14% with albumin colloid, sulphur colloid, sestamibi and teboroxime. Labelling stability was high (> 95% at 4 h and > 80% at 24 h) for all agents except sestamibi (52% at 4 h and 5% at 24h). Exametazime did not alter white blood cell adherence. Albumin colloid, sestamibi and teboroxime decreased adherence and sulphur colloid increased adherence. Exametazime appears to be the best agent for labelling white blood cells. Teboroxime, however, is a new agent for labelling white blood cells which deserves further investigation.