Thin-Section CT Evidence of Bronchial Thickening in Children with Stable Asthma: Bronchoconstriction or Airway Remodeling?

Abstract

Rationale and Objectives The authors performed this study to determine if bronchial wall thickening is present in children with moderate to severe asthma during periods free from clinical bronchoconstriction. Materials and Methods The authors obtained low (radiation) dose thin-section computed tomographic (CT) scans in each of 18 control subjects and 21 children with moderately severe but stable asthma. Spirometry was performed on all subjects at the time of CT scanning. Bronchial wall thickness and bronchial wall area were measured, and the percentage wall area (bronchial wall area divided by bronchial cross–sectional area) was calculated. The authors performed best–fit regression analysis of wall thickness and percentage wall area versus bronchial diameter and qualitative analysis of images for bronchial wall thickening. Results In asthmatic patients, the mean percentage of the predicted forced expiratory volume in 1 second was 0.88 ± 0.09. The best fit regression line that demonstrated the relationship between wall thickness and bronchial diameter for patients with asthma differed significantly from that for control subjects ( P < .005). The regression line that demonstrated the relationship between the percentage wall area and bronchial diameter for patients with asthma differed from that of the control subjects when bronchial wall thickness measurements were used to calculate the percentage wall area ( P < .05). Results of qualitative analysis also showed significantly more bronchial wall thickening in asthmatic patients than in control subjects ( P < .001). Conclusion Bronchial wall thickening detected at thin–section CT in children with moderately severe asthma cannot be attributed solely to bronchoconstriction and may represent airway inflammation or remodeling.