A modified [125I]fibrinogen technique for thrombus detection in the whole leg.

The [125I]fibrinogen uptake test was modified to give a quick result, and improve sensitivity and specificity in the diagnosis of deep venous thrombosis (DVT). At least 800 counts were recorded at each measuring point. The leg veins were emptied more effectively. Thus the proximal thigh could be evaluated and the influence of varicose veins reduced. The feet and the leg points were measured in a zig-zag order (from side to side) to avoid systematic errors in early diagnosis. The modified test detected 62% of the thrombi 1 h after injection, 82% after 1 day and 95% after 2 days. The method still lacks in specificity; this is unavoidable since fibrin accumulates in various other conditions than DVT. The combination of high sensitivity and low specificity makes the modified test reliable as a screening procedure, but not as an independent method.