The validity of hyperdense lumen sign in non-contrast chest CT scans in the detection of pulmonary thromboembolism

Abstract

It is possible to identify high-attenuation clots in pulmonary thromboembolism using non-contrast computed tomography (CT) of the chest. Such detection may be crucial for timely initiation of appropriate therapy. This study was undertaken to determine the validity of the hyperdense lumen (high-attenuation clot) sign in unenhanced chest CT in detecting pulmonary thromboembolism. Non-contrast and contrast-enhanced CT images of the chest of 121 patients who had undergone standard CT pulmonary angiography (pulmonary CTA) were reviewed separately. The absence or presence of luminal hyperdensities within the pulmonary arteries in the non-contrast images was determined. The average CT attenuation differences between the high attenuation clots and pulmonary arteries were computed. Findings in the non-contrast images were correlated with the contrast-enhanced images. Twenty-five patients were positive for pulmonary thromboembolism in the pulmonary CTAs. Of these 25 patients, nine were positive for the hyperdense lumen sign in the non-contrast CT images. The hyperdense lumen sign has an over-all sensitivity of 36.0%, specificity of 99.0%, PPV of 90.0%, and NPV of 85.6% (κ=0.449; P-value<0.001). In detecting central thromboembolism, the sensitivity, specificity, PPV, and NPV of this sign were 66.7, 99.1, 88.9, and 96.4%, respectively (κ=0.740; P-value<0.001). The sign was less sensitive in peripheral thromboembolism (κ=0.358; P-value<0.001). The mean (±SD) attenuation difference between the clot and pulmonary blood pool was 22.76 (±4.20) HU (P-value<0.001). The hyperdense lumen sign is a useful indicator of acute pulmonary thromboembolism in non-contrast chest CT scans particularly in cases involving the central pulmonary arteries.