Correlation between airflow limitation and airway dimensions assessed by multidetector CT in asthma

Asthma is characterized by variable airflow obstruction and airway wall thickening. Multidetector-row computed tomography (MDCT) is useful for the evaluation of airway wall structural changes in asthma. The objective of the study is to assess the relationship between airflow limitation and airway dimensions from the third to fifth generation bronchi in asthma using MDCT.

Thirty-eight subjects with asthma underwent MDCT to measure the airway wall area (WA) and luminal area (Ai), WA and Ai corrected by body surface area (BSA), up to the fifth generation of the apical bronchus (B1) and the posterior basal bronchus (B10) of the right lung.

WA/BSA, WA percentage (WA%) and Ai/BSA in the fifth generation were significantly correlated with forced expiratory volume in 1 s (FEV(1))% predicted. The correlation coefficients between WA% and FEV(1)% predicted increased when tracking the airways from the third to the fifth generation (r=-0.25, p>0.05; r=-0.40, p<0.01; r=-0.63, p<0.001 for B1; r=-0.23, p>0.05; r=-0.47, p<0.01; r=-0.69, p<0.001 for B10). At the generation 5, WA% was greater and Ai/BSA was smaller in severe asthma than mild-to-moderate asthma.

These results suggest that airway flow limitation in asthma is closely related to the more distal airways (third to fifth generation).