Platelet labeling with 67Ga chelates

68Ga-labeled platelets could be useful for positron emission tomographic (PET) studies. In order to identify the optimal chelate for radiolabeling of platelets with 68Ga, we investigated the platelet uptake of 67Ga-oxine, -tropolone and -MPO. The platelet uptake of 67Ga-oxine and -tropolone is very low (<5%). The platelet uptake of 67Ga-MPO, in contrast, increases with platelet density (highest at 109 platelets/ml) up to 18%. Our data provide evidence that only 68Ga-MPO could be useful for PET-studies.