Bronchiectasis is frequent in smokers with COPD, however there is only limited data on objective assessments of this process.
To objectively assess bronchovascular morphology, calculate the ratio of the diameters of bronchial lumen and adjacent artery (BA ratio), and identify those measurements able to discriminate bronchiectasis.
We collected quantitative computed tomography (QCT) measures of BA ratios, peak wall attenuation, wall thickness (WT), wall area, and wall area percent (WA%) at matched 4th-6th airway generations in 21 ever smokers with bronchiectasis (cases) and 21 never-smoking controls (control airways). In cases, measurements were collected at both bronchiectatic and non-bronchiectatic airways. Logistic analysis and the area under receiver operating characteristic curve (AUC) were used to assess the predictive ability of QCT measurements for bronchiectasis.
The whole-lung and 4th-6th airway generations BA ratio, WT, and WA% were significantly greater in bronchiectasis cases than controls. The AUCs for the BA ratio to predict bronchiectasis ranged from 0.90 (whole-lung) to 0.79 (4th-generation). AUCs for WT and WA% ranged from 0.72 to 0.75 and from 0.71 to 0.75. The artery diameters but not bronchial diameters were smaller in bronchiectatic than both non-bronchiectatic and control airways (P<0.01 for both).
Smoking related increases in the BA ratio appear to be driven by reductions in vascular caliber. QCT measures of BA ratio, WT, and WA% may be useful to objectively identify and quantify bronchiectasis in smokers.