In vivo imaging and evaluation of platelet accumulation vs. time at arterial injury site.

The feasibility of quantitatively imaging platelet deposition over time following angioplasty of the abdominal aorta in a rabbit model, with and without antiplatelet treatment, was investigated. Ten male 3-4 kg rabbits were balloon de-endothelialized and placed on 2% cholesterol diet for eight weeks. Group A was untreated. In Group B, donors and recipients were treated with aspirin (5 mgm/kg) prior to and after angioplasty. Platelets were labelled with indium-111. Labelled platelets were injected just prior to PTA and images of 100,000 counts were obtained immediately and at 30 minutes, 1 hour, and 24 hours. In Group A, increased activity of angioplasty site vs. nonangioplastied aorta was seen immediately. This focal increase became more marked in hypercholesterolemic animals over the 24-hour period. In Group B, both hypercholesterolemic and normocholesterolemic, no focal uptake could be documented on sequential scans. This method and model are promising for in vivo evaluation of platelet-vessel wall interactions, in the setting of angioplasty and antiplatelet therapy.