[The clinical application of electron beam tomography in the diagnosis of pulmonary thromboembolism].

Objective: To evaluate the clinical significance of electron beam computerized tomography (EBCT) in the diagnosis and differential diagnosis of pulmonary thromboembolism (PTE).

Methods: EBCT was performed before March 2004 in 114 consecutive patients with clinically suspected pulmonary vascular diseases, including 76 patients with PTE, 29 with pulmonary arteritis, 5 with primary pulmonary arterial tumor, and 4 with pulmonary arterial invasion by lung or mediastinal carcinoma. EBCT was performed using Imatron C-150 scanner with enhanced continuum volume scan (CVS). The slice thickness was 3 mm with scanning time of 0.1 s. The total amount of contrast media (Omnipaque-300) used was 50-100 ml, with flow rates of 3.0-4.0 ml/s and a delay time of 14-25 s.

Results: Deep venous thrombosis (DVT) was confirmed in 58 (76.3%) of the 76 patients with PTE (52 men and 24 women), 8 (10.6%) of them without apparent causes. Of the 2 356 pulmonary arterial branches observed in the 76 cases, 1,668 branches (70.8%) showed signs of PTE, with 545 branches (32.7%) of the central pulmonary arteries and 1 123 branches (67.3%) of the peripheral pulmonary arteries. Central type filling defect, such as the "railway sign" or the "drifting sign", was specific for acute thrombosis. Thrombus calcification was a specific sign of chronic PTE. Indirect signs of PTE included mosaic signs, enlargement of the right ventricle and atrium, pulmonary artery enlargement, pulmonary infarction, pericardial and/or pleural effusion, pulmonary atelectasis and pulmonary consolidation. Pulmonary arteritis (including pulmonary arterial involvement in Takayasu arteritis) was diagnosed by EBCT in 27 (93.1%) of the 29 patients, in which the diagnosis was confirmed by pulmonary angiography in 16, and clinically in 13 Patients. Of the 5 patients with primary pulmonary arterial tumor confirmed by pathology, 1 was misdiagnosed by EBCT. Of the 4 patients with pulmonary arterial involvement by lung or mediastinal carcinoma, 3 were confirmed by surgery and 1 by pulmonary angiography.

Conclusions: DVT and PTE are different manifestations of one disease. The diagnostic strategy aims to detect thrombosis in the pulmonary arteries and in the deep veins of the lower limbs at the same time. EBCT is an effective and non-invasive examination in the diagnosis and differential diagnosis of PTE. By EBCT, acute and chronic thrombi can be initially differentiated, and changes in lung parenchyma, mediastinum, and the pulmonary and systemic arterial walls can be observed, and therefore more valuable radiological information can be collected for clinical decision-making.