A new stannous agent kit for labelling red blood cells with 99TCM and its clinical application.

99Tcm is chosen for labelling erythrocytes for vascular imaging to take advantage of the physical properties of the radionuclide. A new procedure is described which belongs to the category of pre-treatment methods using a kit. Stannous pyrophosphate is the specific reducing reagent. The technique is easier than already published methods: it consists of adding the above reagent to 2 ml. of heparinized blood, waiting five minutes and discarding the serum after centrifugation, then adding the radioactivity required as 99TcmO4. Labelling yield is superior to 95 per cent. The influence of technetium concentration of the pertechnetate solution on the labeling yield is evaluated and compensated by a slight adjustment of tin concentration when necessary. In vitro and in vivo stability studies show that 99Tcm-labelled red cells are suitable for determination of red cell volume, spleen and placental imaging, particularly in emergencies and in paediatrics.