High-Resolution Computed Tomography Evaluation of Peripheral Airways in Asthma Patients: Comparison of Focal and Diffuse Air Trapping

Abstract

Background: Air trapping evaluated in high-resolution computed tomography (HRCT) reflects changes in small bronchi. We simultaneously evaluated focal and diffuse air trapping in asthmatic patients. Objectives: (1) To evaluate air trapping and bronchial wall thickness in asthmatics. (2) To estimate the relationship between air trapping and bronchial wall thickness, pulmonary function tests (PFTs), age, gender and asthma severity. (3) To compare air trapping between subgroups of asthmatic patients with normal FEV₁ % pred. and FEV₁/FVC % and controls. (4) To compare air trapping and bronchial wall thickness between aspirin-induced asthmatics (AIA) and aspirin-tolerant asthmatics (ATA). Methods: Both groups (asthmatics and controls) included 30 patients. All patients underwent HRCT and PFTs. Results: Focal (p < 0.0001) and diffuse (p = 0.0004) air trappings and bronchial wall thickness (T: p < 0.0001; T/D: p < 0.0001; WA%: p < 0.0001) were significantly greater in asthmatics. Focal and diffuse air trappings were inversely correlated (p = 0.021). Diffuse air trapping correlated with bronchial wall thickness: T/D (p = 0.047), T (p = 0.037), and WA% (p = 0.048). There was a significant difference in the extent of focal air trapping between a subgroup of asthmatics with normal FEV₁ % pred. and FEV₁/FVC % and controls (p < 0.0001). There were no significant differences in focal (p = 0.095) and diffuse air trapping (p = 0.186) and bronchial wall thickness (T: p = 0.086; T/D: p = 0.428; WA%: p = 0.428) between AIA and ATA patients. Conclusions: Both focal and diffuse air trappings provide valuable diagnostic information and therefore deserve to be estimated. The lack of significant differences in air trapping and bronchial wall thickness between AIA and ATA patients needs further investigation.