Tc-99m HMPAO as a potential platelet labelling compound

First results of platelet labelling with Tc-99m hexmethylproplene-amineoxime (HMPAO) in-vitro (n=7) and in vivo (n=3) are described. After platelet isolation the best incubation time is 20 min (37 deg.C). The in-vitro Tc-99m elution out of platelets amounts to about 7%/60 min. After reinjection of the labelled cells, the organ distribution of Tc-99m is comparable to activity distribution patterns after In-111-oxin labelling with a maximum in the spleen, minor activity in the liver and total visualisation of the blood pool. Already after reinjection of the cells a kidney and bladder activity can be seen as a consequence of tracer excretion. The localisation of bowel activity after 2h p.i. also is a consequence of a Tc-99m complex elution through the intestine. A positive demonstration of Tc-99m HMPAO labelled platelets uptake in a fresh thrombus can be demonstrated. (author). 12 refs.; 6 figs