The aim of this study was to determine the frequency of diagnostic findings of bronchiectasis on thin-section CT and the usefulness of those findings in distinguishing patients with cylindrical bronchiectasis from healthy subjects.

The study was retrospective and included 26 healthy adults, 10 consecutive patients with surgically proven cylindrical bronchiectasis, and 49 patients who had been prospectively diagnosed at three institutions as having cylindrical bronchiectasis. All patients had 1.0- to 1.5-mm-collimation CT scans obtained at 10-mm intervals through the chest. The CT scans were independently reviewed in random order by two chest radiologists.

Findings in patients with bronchiectasis that were not seen by either observer in any of the healthy subjects included visualization of a bronchus within 1 cm of the costal pleura and visualization of a bronchus abutting the mediastinal pleura. The two observers saw these findings on 96 (81%) and 63 (53%) of 118 CT scans in the 59 patients with bronchiectasis, respectively. Lack of tapering of bronchi was seen in five (10%) of 52 reviews in healthy subjects compared with 95% of reviews in patients with bronchiectasis. Bronchoarterial ratios greater than 1 were identified in 11 (21%) of 52 reviews in healthy subjects compared with 95% of reviews in patients with bronchiectasis. We calculated good agreement between the two observers (kappa values equal to or greater than .63).

In most cases, thin-section CT allows reliable distinction of patients with cylindrical bronchiectasis from healthy subjects.