Detection of intracardiac thrombi by scintigraphy with indium111-labeled platelets. Correlation with 2-dimensional echography and cardiac scanning]

The aim of this study was to use scintigraphy with Indium III marked platelets to detect intracardiac thrombi. Platelet marking was performed with the patient's own platelets and Indium III oxinate. The date was recorded and treated with a gamma-camera-computer system. The results obtained in 45 patients (36 male, 9 female, aged 38 to 80 years, mean age 61 years) were compared with those of 2D echocardiography in all cases, and with CAT in 30 cases. Seventeen patients (13 myocardial infarcts, 2 cardiomyopathies with dilatation, 2 mitral stenoses) were considered to have intracardiac thrombi on platelet scintigraphy with foci of hyperfixation increasing with time, clearly distinguishable from circulating cardiac activity. Sixteen of these cases had appearances of thrombosis on 2D echo (14 left ventricle, and 2 left atrium) and 12 cases had a triple positive result (2D echo, CAT and platelet scintigraphy). One patient had positive platelet scintigraphy and negative 2D echo and CAT. In the 24 cases with negative platelets scintigraphy, an intracardiac thrombus was demonstrated by 2D echo and CAT scanning in 2 cases. Two out of 4 patients with transient hyperfixation had appearances of a large chronic thrombus on 2D echo and CAT. The efficacy of therapy was monitored in 3 patients on heparin and 4 patients on platelet antiaggregants. These results show that platelet scintigraphy is a highly specific method of detecting intracardiac thrombi. It is less sensitive than 2D echo because it depends on the haematological activity of the thrombus, making it a useful technique for assessing the efficacy of therapy.