The Value of Spiral Computed Tomography in the Diagnosis of Pulmonary Embolism

Lee, Sung Soon; Lim, Chae Man; Song, Koun Sik; Sung, Kyu Bo; Koh, Youn Suck; Lee, Sang Do; Kim, Woo Sung; Kim, Dong Soon; Kim, Won Dong

Abstract

OBJECTIVE
Spiral volumetric computed tomography(spiral CT) has the advantage of direct imaging of intravascular thrombus or its relevant vascular abnormalities, but controversy exists about the value of spiral CT in the diagnosis of pulmonary embolism in the different levels of pulmonary artery.
METHODS
The authors prospectively evaluated the diagnostic efficacy of spiral CT for pulmonary embolism in 20 patients (M:F=13:7, 57+/-10.4yrs) who were suspected to have pulmonary embolism from clinical symptoms and/or scintigraphic findings. Both spiral CT and pulmonary angiography were performed in these patients with the interval being 28+/-14.1 hours. The diagnostic efficacy of spiral CT was evaluated in the patients and also in the pulmonary arteries found to have emboli on pulmonary angiogram.
RESULTS
Pulmonary embolism was diagnosed in 8 patients and excluded in 12 patients by pulmonary angiography. Spiral CT showed positive findings of pulmonary embolism in 7 of the 8 patients with pulmonary embolism, and was negative in 11 of the 12 patients without pulmonary embolism. The overall diagnostic efficacy of spiral CT for pulmonary embolism was: sensitivity 87%(7/8), specificity 92%(11/ 12), positive predictive value 87%(7/8), negative predictive value 92%(11/12), and accuracy 90%(18/20). For pulmonary embolism at lobar or greater pulmonary arteries, the diagnostic efficacy of spiral CT was: sensitivity 100%(15/15), specificity 98%(201/205), positive predictive value 79%(15/19), negative predictive value 100%(201/201), and accuracy 90% (216/220). For segmental or smaller arteries, how- ever, the diagnostic efficacy was: sensitivity 71%(15/ 21), specificity 98%(549/559), positive predictive value 60% (15/25), negative predictive value 99%(549/555), and accuracy 97%(554/580).
CONCLUSION
Spiral CT can be a useful noninvasive method for the diagnosis of pulmonary embolism, and it may replace pulmonary angiography at the level of central pulmonary artery.