Utility of Indium-111 Labelled Platelet Scans in Assessing the Dynamics of Thrombovascular Lesions. An Experience with 70 Patients

In prior reports we have described ¹¹¹In labelling of platelets and shown their effectiveness in scintigraphic imaging of thromboses and vascular injury in experimental animals and preliminarily in man (Lancet: June: 1185-1187,1978). Our current experience is with 70 patients. In 27 patients with transient ischemic attacks, ¹¹¹In-platelet scans were positive in the neck for 17/34 carotid artery lesions, evident on angiograms. Scans were negative in 12/14 negative arterial angiograms. 3/6 patients with completed stroke’s had positive scans. 21 of these 33 patients were taking anticoagulant (AC) or antiplatelet drugs. Results were somewhat improved in patients off such drugs. Although mean platelets survival was not shortened, there was a greater SD as compared with normals (6.99±1.79 vs. 7.16±0.44 days). In venous thromboembolism 7/7 positive leg scintigrams were confirmed. Of six patients with pulmonary emboli, the only one not on AC, had ¹¹¹In-accumulation locally in the suspected site in the lung. A miscellaneous group of thrombin were also detected. At present ¹¹¹In-platelets cannot replace contrast angiography, but may te an initial diagnostic approach particularly in patients not on AC. More importantly, mIn-platelet accumulation is a physiological test and may be an index of thrombus growth activity and a potential guide to drug therapy, rather than a static anatomic measurement {angiogram).