[Pulmonary thromboembolism and diagnostic imaging: integration of techniques and methods]

Thromboembolism is presently the third most frequent cardiovascular disease, with an incidence of deep venous thrombosis of 800,000 cases a year in the USA. The clinical diagnosis of the condition is difficult and noninvasive procedures are poorly reliable, which makes the diagnosis and treatment of deep venous thrombosis appropriate in the patient with clinically suspected pulmonary embolism. Color-Doppler US is now replacing phlebography in the diagnosis of deep venous thrombosis. Proximal deep venous thrombosis is always at high risk for embolism (50%). Isolated calf thrombi may spread into proximal veins and thus cause severe embolism. Therefore, the early detection of thrombus site and extent and a timely treatment before embolism are of the utmost importance. Color-Doppler US is a noninvasive technique which can show deep venous thrombosis with 95% sensitivity in the proximal and 55% sensitivity in the distal districts in asymptomatic patients. This examination must be used not only to confirm a diagnostic suspicion of deep venous thrombosis, but also to screen high-risk patient and to monitor distal thrombosis. In the secondary prophylaxis of pulmonary embolism, the radiologist must perform a mechanical interruption of inferior vena cava by positioning a caval filter. Caval filters can be temporary or definitive; standard indications for caval filter positioning are a contraindication to anticoagulant therapy and the onset of pulmonary embolism in spite of anticoagulant drugs. A further indication is the presence of floating thrombi in the femoroiliac-caval trunk. Multidisciplinary groups including the hematologist, the radiologist and the clinician should plan the diagnostic and therapeutic approach and participate in the decision-making process. In our department, from January, 1992, to June, 1995, sixty-five caval filters were positioned in 62 patients selected out of 260 candidates. Three complications only were observed; one patient had recurrent pulmonary embolism and three patient had caval thrombosis spreading beyond the filter. In 198 patients in whom no caval filter was implanted, pulmonary embolism did not recur. At present, the role of the radiologist is markedly changing, especially in the management of this condition. On the one hand, radiologists must diagnose thromboembolism as a whole and not only its pulmonary evidence; on the other hand, they play a major operational and interventional role in the treatment of thromboembolism patients.