THIN-SECTION CT FINDINGS OF THE LUNGS - EXPERIMENTALLY-INDUCED BRONCHIAL AND PULMONARY-ARTERY OBSTRUCTION IN PIGS

OBJECTIVE. The purpose of this study was to investigate whether a mosa ic pattern of lung attenuation, or lobular low attenuation, is reveale d on CT imaging after induction of bronchial and pulmonary artery obst ruction in pigs. MATERIALS AND METHODS. Eight anesthetized and ventila ted pigs, four for bronchial obstruction and four for pulmonary artery obstruction, were examined with thin-section CT. Bronchial obstructio n was induced at the subsegmental level using 2- to 3-mm radiopaque si licon spheres at 14 sites. Pulmonary artery obstruction was induced at 11 sites by dislodging 2- to 3-mm silicon spheres at the level of the superior vena cava. CT scans were obtained at end expiration immediat ely after the obstruction in all pigs (n = 8) and after 1 day (n = 3), 3 days (n = 5), 7 days (n = 4), 14 days (n = 4), and 28 days (n = 3). RESULTS. Of the 14 sites of bronchial obstruction, six sites (43%) on the immediate scans showed a lobular distribution of low attenuation distal to the spheres, which changed to atelectasis, consolidation, or normal on follow-up CT. Of the four sites that did not show changes i n lung attenuation on immediate CT scans, two sites showed lobular low attenuation after 1 day. The mean attenuation value +/- SD for the lo bular low attenuation was -737 H +/- 122 and that of the adjacent lung was -522 H +/- 53 (p = .0077). None of the pulmonary artery obstructi on sites showed visible change in lung attenuation, and mean attenuati on values for obstructed sites and unobstructed sites did not show sig nificant differences when scanned as many as 28 days after the immedia te scans. CONCLUSION. Lobular low attenuation on thin-section CT was i nduced by bronchial obstruction, but we found no change in lung attenu ation due to obstruction of the pulmonary arteries as many as 28 days after the immediate scans.