High-resolution CT quantification of bronchiectasis: clinical and functional correlation

Purpose: To evaluate clinical relevance of high-resolution computed tomographic (CT) findings in patients with bronchiectasis by using a quantitative high-resolution CT protocol to assess extent of bronchiectasis, severity of bronchial wall thickening, and presence of small-airway abnormalities and mosaic pattern.

Materials and methods: Sixty Chinese patients with steady-state bronchiectasis underwent thoracic high-resolution CT and lung function tests. Exacerbation frequency per year and 24-hour sputum volume were determined. Extent of bronchiectasis, severity of bronchial wall thickening, and presence of small-airway abnormalities and mosaic attenuation were evaluated in each lobe, including the lingula. Differences between sex and smoking status with respect to high-resolution CT, lung function, and clinical parameters were tested with either the independent sample t test or the Mann-Whitney test. Spearman rank correlation was used to evaluate associations between clinical, lung function, and high-resolution CT scores. Multiple regression analyses were performed to determine which high-resolution CT parameters would best predict lung function and clinical parameters, adjusted for smoking.

Results: Exacerbation frequency was associated with bronchial wall thickening (r = 0.32, P =.03); 24-hour sputum volume with bronchial wall thickening and small-airway abnormalities (r = 0.30 and 0.39, respectively; P <.05); and forced expiratory volume in 1 second (FEV(1)), ratio of FEV(1) to forced vital capacity (FVC), and midexpiratory phase of forced expiratory flow (FEF(25%-75%)) (r = -0.33, -0.29, and -0.32, respectively; P <.05). Extent of bronchiectasis, bronchial wall thickening, and mosaic attenuation, respectively, were related to FEV(1) (r = -0.43 to -0.60, P <.001), FEF(25%-75%) (r = -0.38 to -0.57, P <.001), FVC (r = -0.36 to -0.46, P <.01), and FEV(1)/FVC ratio (r = -0.31 to -0.49, P <.01). After multiple regression analysis, bronchial wall thickening remained a significant determinant of airflow obstruction, whereas small-airway abnormalities remained associated with 24-hour sputum volume. Women had milder disease than men but showed more high-resolution CT functional correlations.

Conclusion: Findings of this study establish a link between morphologic high-resolution CT parameters and clinical activity and emphasize the role of bronchial wall thickening in patients with bronchiectasis.