Introduced in 1968,1 the125I-fibrinogen uptake test has been widely acclaimed as a safe and highly sensitive method of detecting thrombus formation and spread, which are often a prelude to pulmonary embolism. After the thyroid uptake has been blocked by orally administered iodine,125I-tagged fibrinogen injected intravenously becomes incorporated into the fibrin matrix of a developing clot, thus enabling localization by scintillation scanning.
In a recent survey of 935 surgical patients screened at King's College Hospital by radioactive fibrinogen uptake, Kakkar2 reported detection of phlebothrombosis in legs of 248 patients. Thrombi propagated proximally and deeply in 56, in nine of whom pulmonary embolism subsequently occurred. Patients in whom the propagation of the thrombus had been identified and anticoagulant treatment instituted were spared this complication, as, not unexpectedly, were also all patients with a normal scan.
Ideally, according to Kakkar, prevention and treatment of deep vein thrombosis
Expanding Uses of the 125I-Labelled Fibrinogen Uptake Test. JAMA. 1972;221(10):1162. doi:10.1001/jama.1972.03200230048015