[Isotope studies in the diagnosis of venous thromboses and lung embolism]

Early diagnosis of deep venous thrombosis and pulmonary thromboembolism is still a clinical problem and led to the development of non invasive diagnostic methods using radioactive tracers. There are 2 principles of procedures. One is diagnosing deep venous thrombosis with the 125 (131) iodine-fibrinogen uptake-test. The use of 125 (131) J fibrinogen, its advantages and disadvantages are described. Others are imaging techniques developed as an alternative to ascending contrast venography still considered as the "golden standard", using 99m Tc labelled microspheres of human serum-albumin or Tc 99m labelled red blood cells (blood pool imaging). In spite of certain discrepancies a good correlation of 90% exists, between the imaging methods mentioned. Several authors reported a sensitivity of 87% and a specificity of 85% as compared with Doppler-ultrasound Investigations of lower extremities. A great advantage of radionuclidvenography is the possible combination with lung-perfusion scanning for the diagnosis of pulmonary embolism. Lung-perfusion- and ventilation-studies are still the only non invasive method to diagnose pulmonary embolism. Sensitivity of this method is very high, specificity improves with taking in account predisposing factors of developed deep vein thrombosis. Indium 111 or 99m Tc labelled monoclonal antifibrinantibodies are developed recently: an imaging agent suitable for evaluation of both pelvic and lower extremity vein thrombosis. First promising results were published last year and it seems, that this reliable imaging agent for clots and thrombo-embolic diseases will fill this diagnostic need in the future.