High-resolution computed tomography of airway changes after induced bronchoconstriction and bronchodilation in asthmatic volunteers

Rationale and Objectives. We examined whether high-resolution computed tomography (HRCT) would detect and quantify induced airway changes in asthmatic volunteers. Methods. We performed pulmonary function tests and HRCT on eight asthmatic adults and two nonasthmatic control adults under three conditions: baseline, after methacholine inhalation, and after albuterol inhalation. Changes in pulmonary function, airway internal luminal diameter (AILD), and airway wall thickness (AWT) in the three conditions were compared. Results. After methacholine inhalation, pulmonary function showed significant airflow obstruction in the asthmatic volunteers compared with two nonasthmatic control volunteers. The median value for AILD decreased by 17% (p = .04). After subsequent inhalation of albuterol, pulmonary function improved to above the baseline levels in the eight asthmatic volunteers. The median value for AILD increased by 18% above the baseline value (p = .0001). No changes in pulmonary function or AILD were seen in the two nonasthmatic volunteers. AWT did not change significantly in either the asthmatic or nonasthmatic volunteers after inhalation of methacholine or albuterol. Conclusion. HRCT can quantify changes in the internal luminal diameter of asthmatic airways provoked by methacholine and albuterol inhalation.