Experimental radioimmunoimaging of 99mTc monoclonal anti-activated platelet antibody SZ-51 in dogs with arterial and venous thrombin

In experimental canine models of femoral arterial and venous thrombosis, the feasibility of thrombus imaging with 99mTc labeled monoclonal antibody SZ-51 to an α-granule membrane protein (GMP-140) on the surface of activated platelets was investigated. Both the arterial and venous thrombin were clearly discernible at 2-8h after injection. The optimal imaging time was 4-6h. These results were confirmed by in vivo images of thrombosed arteries and veins followed by killing the dogs at 8h post injection. Quantitative imaging analysis showed that the ratios between the thrombus and the opposite vessel were increased strikingly over time. The ratios of thrombus to blood or surrounding muscle were 57.09 +- 12.24 and 177.46 +-9.00 for arterial thrombosis and 6.43 +- 4.70 and 83.22 +- 68.98 for venous one at the time of sacrifice, respectively. Radiolabeled antibody was cleared from the blood with T1/2α of 16.25 +- 13.39 min T1/2β of 7.28 +- 1.15 h. These results show that it is feasible to noninvasively detect the thrombus formation in vivo using 99mTc labeled monoclonal antibody SZ-51