111In-labeled platelet scintigraphy was carried out in 20 patients suspected of thrombosis, to evaluate its efficacy for the detection of intracardiac and intravascular thrombi. Hemostatic studies including PT, aPTT, fibrinogen, FDP, platelet retention by Hellem II method, platelet aggregation induced by ADP (1μM, 10μM), collagen (2μg/ml) and arachidonate (2mM), and platelet survival were examined simultaneously. Two of these patients were also studied by fibrinogen scintigraphy labeled with 99mTc. The platelets obtained from the patients were labeled with 111In-oxine according to a method originated by Yui et al.
In the platelet scintigram, positive findings were demonstrated in 9 cases: 2 left ventricular, 3 left atrial, and 4 vascular thrombi. These were in a good accordance to the findings obtained by at least one from angiography, echography and surgery.
Platelet aggregation induced by 1μM ADP was elevated in 4 of the 7 patients with positive findings and 3 of the 7 patients with negative findings. Shortened platelet survivals were observed in two of the 10 patients; dissecting aortic aneurysm and infective prosthetic valve endocarditis with hepatosplenomegaly. There was no significant difference in the platelet function and the platelet survival between the patients with positive and negative findings.
It was difficult to detect thrombi by the fibrinogen scintigraphy labeled with 99mTc in the two patients studied.
In conclusion, 111In-labeled platelet scintigraphy seems to be very useful to detect thrombi.
