Detection of deep venous thrombosis with indium 111-labelled monoclonal antibody against tissue plasminogen activator

Abstract

The administration of a radiolabelled monoclonal antibody against tissue plasminogen activator allows detection of areas with increased fibrinolytic activity, i.e. those with an active thrombotic lesion. Eight patients with phlebographically verified deep venous thrombosis were examined. At the time of immunoscintigraphy study they were examined receiving anticoagulant therapy. Some 75-85 MBq indium 111-labelled antibody were injected, and scintigrams were obtained after 30 min and after 24 h. The precise site of the thrombus could not be visualized after 30 min due to high background activity, whereas after 24 h it was detectable in all patients. The thrombus/background ratios achieved are twice as high as those observed in a human antifibrin antibody study. These preliminary data suggest a high sensitivity of our t-PA-specific antibody for the detection of active deep venous thrombosis in man, and our antibody seems to offer theoretical advantages over both platelet and fibrin-specific antibodies.

Thrombus Imaging with 99mTc-Hmpao-Labeled Platelets and 111In-Labeled Monoclonal Antifibrin Antibodies

“…Some false-posi tive findings with In-MoAbs have been reported (2). The thrombus-to-blood ratios in our study were of about the same order as described earlier with 59D8 and tissue plasminogen activator antibodies (2,7,17).…”

An indium:calcium phosphate colloid that specifically targets fibrin

“…Although early investigations used indium labeled white blood cells or platelets as labeling agents [6,11,12], others have shown the benefits of using indium conjugated to fibrinogen [13] or fibrin-associated proteins such as plasminogen activator [14] or fibronectin [15]. Indium conjugated to monoclonal antibodies directed against fibrin itself [16][17][18][19][20][21][22] and fragments thereof [23], as well as, tissue plasminogen activator [39] have also been used. Indium labeled antimyosin antibodies have proven successful not only in the detection of acute myocardial infarction [24][25][26], but also in asymptomatic 'silent' myocardial infarction [24,27,28], as well as, differentiation of myocarditis [15].…”

“…In this study we sought to evaluate if CaP could also mediate fibrin deposition of low molecular weight components such as the radionuclide 114m In. Because of its biocompatibility [39], ease of preparation and high affinity for fibrin [37,38,40], CaP could be of potential value for indium-based imaging studies to identify regions of occult vascular stenosis (i.e., atherosclerotic plaques, deep vein and pulmonary emboli). …”