Detection Of 111-Indium Labelled Platelets In Experimental Venous Thrombosis

Successful detection of Indium-lll-oxine labelled platelets in venous thrombi offers a new meth od of diagnosis of venous thrombosis. Femoral vein thrombosis was established in 20 dogs by a combination of partial venous occlusion and vein electrification. In this model, thrombosis is first detectable on venography after 48 hours. Autologous labelled platelets were re-injected into each dog; a sham operation having been performed on the opposite femoral vein. Bilateral venography was performed 2 days and 7 days post-operatively and each dog was sacrificed after removal of femoral veins. Isotopic detection of venous thrombosis was determined by comparison of scintillation counts over each femoral vein daily for one week.

Ratios of isotope counts between abnormal and normal legs indicated thrombus formation in 8 out of 10 dogs with known thrombi;two false negative results were due to hematoma formation. The mean duration of detection was 2.5 days. The counts were higher over venous thrombi in 3 out of 4 dogs who received platelet labelling prior to thrombus formation. Here, the mean duration of detection was 4 days. In 6 control animals, where veins were partially occluded only, counts were similar in each leg.