Gallium 68 labeled red cells and platelets: new agents for positron tomography

Red cells and platelets are labeled with Ga 68 by preparing the Ga 68 hydroxy quinoline (oxine) complex and mixing the complex with the separated cellular components. The complex is prepared by first breaking the Ga 68 EDTA chelate with concentrated hydrochloric acid, adsorption of the gallium on a strong anionic ion exchange column, and elution of the gallium activity with distilled water. Oxine is added, the oxine complex extracted into chloroform and following evaporation and dissolution, the solution is added to either red cells or platelets that have been centrifuged from whole blood, washed, and suspended in normal saline. After 15 min of incubation, labeling efficiencies of >90% and yields of ∞7 mCi are obtained from 18 mCi of Ga 68 EDTA eluted from the generator. After injection of the gallium labeled red cells in dogs, excellent blood pool images were obtained by positron tomography. The distribution corresponded to that of ¹¹CO labeled red cells. When labeled platelets were injected into dogs with experimentally induced intimal injury of on carotid artery, the area of injury was clearly visualized 40 min after tracer injection.