The Complementary Roles of Chest Radiography, Lung Scanning, and Selective Pulmonary Angiography in the Diagnosis of Pulmonary Embolism

Abstract

The chest X-ray, perfusion lung scan, and selective pulmonary arteriogram were independently reviewed in 104 patients with suspected pulmonary embolism. Thirteen patients also had 133 Xe ventilation studies. Of the 45 patients with angiographically-documented pulmonary emboli, 37 had perfusion scans interpreted as high probability of pulmonary embolism (82% sensitivity). Fifty of 59 patients without angiographic evidence of pulmonary embolism had perfusion scans interpreted as low probability of pulmonary embolism, other , or normal (85% specificity). Of the 41 patients with acute pulmonary embolism, only three had normal chest X-rays. In 26 (63%) the abnormality on perfusion scan was more extensive than that on chest X-ray. When both the scan and chest X-ray pointed strongly in the same direction, a correct diagnosis could usually be made, and accuracy was greater than when diagnosis was based on the perfusion scan alone. The lung scan was of limited value in patients with cardiomegaly or left heart failure. The differential role of the 133 Xe ventilation study remains unclear. On the basis of the present and other data, guidelines for the selection of patients for pulmonary arteriography are proposed.