Noninvasive detection of coronary thrombi with In-111 platelets: concise communication.

The need for rapid, definitive identification of coronary thrombosis has been intensified by the advent of thrombolytic therapy and by interest in the role of thrombosis in the etiology of coronary artery disease. To determine whether platelet thrombi can be detected noninvasively with In-111 platelets, a method was developed in which Tc-99m-tagged red blood cells were used to correct for activity within the blood attributable to platelets circulating but not associated with thrombus. In 18 dogs coronary thrombi were induced closed-chest with a copper coil introduced into the coronary artery. Indium-111 platelets and Tc-99m RBCs were administered either before or 1 hr after induction of thrombus, and serial scintigrams obtained. Coronary thrombus was identified readily in the processed scintigrams. In six dogs, thrombolysis was achieved with intracoronary streptokinase. In each case serial scintigraphy demonstrated resolution of the clot. The dual radiotracer technique should permit serial noninvasive delineation of the temporal relationship between platelet deposition and coronary heart disease in patients, and should facilitate the evaluation of interventions designed to prevent platelet aggregation or to lyse existing thrombi.