The 125I-Fibrinogen Method for Early Diagnosis of Venous Thrombosis

Abstract

In vitro and in vivo experiments were performed with a scintillation detector designed for 125I-fibrinogen measurements. The sensitivity of the detector was tested in a water phantom. The relative count rate of 100 when the 125I point source was applied to the water surface decreased to 50 at a water depth of 1 cm to 14 at 2.5 cm, and to 4 at 4 cm. Measurements on normal patients showed that the individual standard deviation of day-to-day measurements of the count rate on the calf was ±2.0% of the count rate over the heart. Based on these data, we decided that a 10% increase in this "percentage count rate" between preoperative recordings and recordings made at 2 consecutive days was suggestive of thrombosis. Of 36 high-risk patients subjected to surgery, 7 (20%) filled this criterion.