Experimental studies with¹¹¹indium-labeled platelets in pulmonary embolism

The effects of several potential modifiers on the detection of experimental pulmonary emboli by indium-111-labeled autologous platelets were studied. Contrast material did not affect embolus visualization; heparin prevented it, but its effect was not irreversible. The addition of exogenous thrombin to the experimental thrombus was not necessary for successful detection of the resulting emboli. Indium-111-oxine detected a small number of emboli without in vitro platelet labeling. Acutely embolized thrombi up to 72 hours old were readily identified by labeled platelets, but emboli older than 24 hours were almost impossible to detect. There was evidence suggesting propagation of emboli within the pulmonary arteries.