Imaging platelet deposition on Dacron bifurcation grafts in man: Quantification by a dual-tracer method using 111In-labeled platelets and 99mTc-labeled human serum albumin

A dual tracer technique using ¹¹¹In-labeled platelets and ^99mTc-labeled human serum albumin was applied to evaluate the thrombogenicity of Dacron bifurcation arterial grafts. The level of platelet accumulation over the whole of the graft was estimated from the ratio of ¹¹¹In-platelet radioactivity deposited on the vascular wall to these radioactivity circulating in the blood pool, i.e., the platelet-accumulation index (PAI). Furthermore, the PAI value was calculated for each pixel in digitized images and the PAI distribution image (PAI image) was reconstructed. Eighteen patients with DeBakey knitted Dacron bifurcation grafts and 11 normal volunteers were studied. Of the 18 patients, 11 had no graft occlusion (group I) and the remaining 7 (group II) had occlusion. The mean PAI value (±SD) over the whole of the graft in group I was 32.6%±33.7% as compared to -8.8%±4.5% in the control group (P<0.01). In group I, the PAI value over the entire graft decreased with the age of the fraft (r=-0.763; P<0.01). In contrast, in group II, platelet accumulation did not diminish with time and persisted beyond the time of which platelet accumulation was no longer found in group I. Moreover, analysis of the PAI images revealed enhanced platelet accumulation on the proximal part of the graft to be more frequent in group II than in group I (6/7 vs 0/11; _c² = 10.55; P<0.005). The method used for platelet imaging in the present study may be useful in the study of platelet reactions on Dacron arterial prostheses.