Scintigraphic methods for detecting vascular thrombus.

Vascular thrombosis is a common and potentially life-threatening condition, but objective diagnosis is highly desirable before anticoagulant therapy is instituted. Existing nonscintigraphic modalities such as contrast venography and ultrasonography can image venous morphology but cannot reliably indicate the hematologic state of thrombi. Radiopharmaceuticals that bind specifically to fibrin or platelets afford the ability to determine whether a thrombus is hematologically active and therefore likely to propagate and/or embolize. Ideally, the test should produce a diagnostic result within a few hours and be capable of imaging thrombi that are several days old. A number of radiolabeled materials have been tested for their ability to bind to and permit scintigraphic detection of thrombi. These have included labeled fibrinogen, autologous platelets, monoclonal antibodies, fibrin fragment E1, plasminogen activators and synthetic peptides that mimic the molecular recognition units of antibodies. The current status of investigation of each of these radiopharmaceuticals is reviewed in this article.