BACKGROUND: In asthma, multidetector row computed tomography (MDCT) detects abnormalities that are related to disease severity, including increased bronchial wall thickness. However, whether these abnormalities could be related to asthma control has not been investigated yet. OBJECTIVE: Our goal was to determine which changes in airways could be linked to disease control. METHODS: Twelve patients with poor asthma control were included and received a salmeterol/fluticasone propionate combination daily for 12 weeks. Patients underwent clinical, functional, and MDCT examinations before and after the treatment period. MDCT examinations were performed using a low-dose protocol at a controlled lung volume (65% TLC). Bronchial lumen (LA) and wall areas (WA) were evaluated at a segmental and subsegmental level using BronCare software. Lung density was measured at the base of the lung. Baseline and end-of-treatment data were compared using the Wilcoxon signed-rank test. RESULTS: After the 12-week treatment period, asthma control was achieved. Airflow obstruction and air trapping decreased as assessed by the changes in FEV(1) (p < 0.01) and expiratory reserve volume (p < 0.01). Conversely, LA and WA did not vary significantly. However, a median decrease in LA of >10% was observed in half of the patients with a wide intra- and intersubject response heterogeneity. This was concomitant with a decrease in lung density (p < 0.02 in the anteroinferior areas). CONCLUSIONS: MDCT is insensitive for demonstrating any decrease in bronchial wall thickness. This is mainly due to changes in bronchial caliber which may be linked to modifications of the elastic properties of the bronchopulmonary system under treatment.