Thoracic CT in pediatric patients with difficult-to-treat asthma

. The aim of this study was to establish objective, simple criteria for bronchial wall thickening in children with difficult-to-treat asthma.

. Bronchial sections were counted at five levels in both lungs and at three levels in the right lung on high-resolution CT and plotted against lung function. Findings from 27 children with persistent symptoms of asthma (mean age, 11.4 years; SD, +/-3.1 years) that were severe (group A, n = 15) or moderate (group B, n = 12) were compared with findings from 21 control subjects (mean age, 10.8 years; SD, +/-3.0 years) using the Student's t test, analysis of variance, and Dunn-Bonferroni test.

. A bronchial wall thickening score based on the number of visible bronchi at three levels (three-level score) proved to be as valuable as and simpler to obtain than a score based on the number of bronchi at five levels (five-level score). The three-level scores for groups A and B were similar (mean +/- SD, 16.8 +/- 4.2 vs 18.4 +/- 3.4, respectively; p = not significant), but these scores were significantly higher than those for the control subjects (mean +/- SD, 8.2 +/- 3.4, respectively; p < 0.001). There was no correlation between the three-level score and forced expiratory volume in 1 sec or forced expiratory flow between 25% and 75% of forced vital capacity. In contrast with adults with severe asthma, our pediatric patients with difficult-to-treat asthma did not have CT evidence of mucoid impaction, emphysema, areas of hyperlucency, bronchiectasis, or sequellar line shadows.

. Bronchial wall thickening visible on high-resolution CT may constitute an additional criterion of asthma severity in children. CT evidence of bronchial wall thickening might help to identify patients with a higher risk of airway remodeling.