Platelet accumulation in abdominal aortic aneurysm and the effect of antiplatelet drugs

A dual tracer technique using 111In labeled platelets and 99mTc labeled human serum albumin was applied to evaluate the in vivo thrombogenicity in 12 cases with abdominal aortic aneurysm (AAA) and the effect of antiplatelet drug on the thrombogenicity. The magnitude of platelet accumulation at AAA was expressed as the ratio of radioactivity of 111In platelets on the vascular wall to those in the blood pool (PAI; platelet accumulation index). Of the 12 patients with AAA, 11 had positive studies on baseline imaging and 1 had equivocally positive image. The PAI value (Mean±SD) over the AAA was 53.8±34.1% as compared to -8.6±4.4% in the control group (p<0.01). Seven patients with an AAA and positive baseline images were restudied during platelet active drug with 325 mg of aspirin. During treatment with aspirin, of 7 patients, 5 had positive images, of which 3 were decreased and others unchanged compared to baseline studies, 1 equivocally positive one and one negative one. The PAI value during treatment (21.9±18.6%) was significantly decreased compared to those in baseline study (52.1±23.9%). Our results suggest that the method used for platelet imaging in the present study may be useful for studying the in vivo thrombogenicity and the effect of platelet active drugs in AAA. (author)