A rapid method for the preparation of 99Tcm hexametazime-labelled leucocytes

Abstract

99Tcm (+/-)-hexamethylpropyleneamineoxime (HMPAO) (99Tcm Hexametazime) has been recently reported as an alternative for labelling leucocytes. For reasons of convenience, radiation dose and image quality, many workers have welcomed this novel approach except for its complicated labelling protocol and venesection of 100 ml. This technique has been modified to give a simpler routine in-house labelling technique. It has three advantages: only about 20 ml of blood is required, the labelling time is just under 1 h and high yields of labelled leucocytes are obtained (mean of 500 MBq per injection dose). The properties of labelled leucocytes using this modified method are; 80% granulocyte-bound radioactivity, a rapid lung transit and a blood granulocyte recovery of 40% at 30 min similar to those described previously. The viability of the labelled leucocytes was tested and confirmed in vitro using a migration technique and in vivo by showing no lung retention on early imaging and high splenic uptake. A rapid in-process chromatography assessment procedure for regulating the protocol has been developed. Successful abscess imaging by 4 h has been achieved in 21 patients with normal results in another 22 patients without abscesses. This simpler method should encourage a more widespread application of scintigraphy using radiolabelled granulocytes.