Tracheal collapsibility measured using end-expiratory chest CT in chronic airway disease

Lee, Sang Ryul; Song, Eun Ju; Baek, Dae Hyun; Lee, Sung Hyuk; Lee, Jae Hyung; Lee, Ki Doek; Lee, Byoung Hoon; Kim, Sang Hoon

Abstract

BACKGROUND/AIMS
Partial tracheal narrowing can occur during expiration in the normal population. It is not certain whether the trachea collapses more readily in chronic airway disease. We evaluated the tracheal narrowing at end-expiration using computed tomography (CT).
METHODS
We investigated 45 patients and 22 normal subjects who underwent high-resolution CT and pulmonary function tests. In each subject, two CT images at the same level of the aortic arch were compared: one at end-inspiration and the other at end-expiration. The cross-sectional area and sagittal diameter of the trachea were measured using a hand-tracing method, using the in-program measuring tools of Medical Image Viewer, and the percentage changes of each value were calculated.
RESULTS
Of the 45 patients with chronic airway disease, 21 had chronic obstructive pulmonary disease, 16 had bronchial asthma, and 8 had bronchiectasis. The mean change in the cross-sectional area was 13.3% in the patients and 9.0% in the normal subjects (p<0.05), and the mean change in sagittal diameter was 11.8 and 9.6%, respectively (p>0.05). The decrease in tracheal cross-sectional area was greatest in bronchiectasis, while the greatest decrease in sagittal diameter was in bronchial asthma. There was no significant difference in tracheal collapsibility among the disease groups. The percent change in the tracheal cross-sectional area was correlated with the % predicted FVC (r=-0.033, p<0.05) and FEV1 (r= 0.277, p<0.05) in both the patients and normal controls.
CONCLUSIONS
The decrease in tracheal cross-sectional area at end-expiration measured using chest CT was greater in chronic airway disease than in normal subjects, and was associated with ventilatory function.