Kinetics and fate of indium 111 oxine-labeled platelets in patients with aortic aneurysms.

The survival and sites of sequestration of indium 111 oxine-labeled autologous platelets were studied quantitatively in six patients with aortic aneurysms. The in vivo distribution was quantitated daily with a scintillation camera and a computer-assisted imaging system. Data of platelet survival curves were fitted to a gamma function model. Mean platelet survival was shortened and the disappearance curves were exponential in all but two patients who had normal platelet survival. Platelet radioactivity in the aneurysm was 5.1 +/- 3% of whole-body radioactivity at the end of platelet survival. Platelet were sequestered in the spleen, liver, and bone marrow. Accumulation of platelets, presumably due to microembolization, was prominent in the lower limbs. This indicates that although platelets were deposited in the aneurysm, many are damaged and are eventually sequestered in the reticuloendothelial system.