Objective    To investigate the differences of airway remodeling in segmental and sub-segmental bronchi between bronchial asthma and chronic obstructive pulmonary disease (COPD) patients by high resolution computed tomography (HRCT).     Methods    HRCT (120 kV

80 to 280 mA

0.6 s) were performed in 34 asthmatic patients

32 COPD patients and 24 health subjects in our department form April 1

2009 to July 20

2010. All these asthmatic patients and COPD patients met the inclusion criteria of the Global Initiative for asthma (GINA) and the Global Initiative for Chronic Obstructive Lung Disease (GOLD)  respectively. Image reconstruction was carried out with a 5 mm collimation at 5 mm intervals and 0.625 mm collimation at 0.625 mm intervals respectively. CT images of segmental bronchi and sub-segmental bronchi were reviewed quantitatively and descriptively. Wall thickness (WT)

inner diameter (Din)

and wall area (WA)

percentage of wall area (WA%) of upper lobe apical segmental and sub-segmental bronchi in the right and left lung

as well as in lower lobe posterior basal segmental and sub-segmental bronchi of right and left lung were detected by bronchus automatic analysis software Thoracic VCAR. The mean values of the 4 parameters were calculated and the differences of these parameters between groups were analyzed.     Results    Bronchial wall thickening and luminal narrowing were found in asthma and COPD patients

and bronchiectasis in some cases. The comparison of segmental bronchi parameters between asthma and COPD patients: there was no difference of WA and WA between 2 groups (P0.05); Din of asthma was smaller than that of COPD (P0.05); WA% asthma was larger than that of COPD (P0.05). The comparison of sub-segmental bronchi parameters between 2 groups: WT

WA and WA% of asthma was smaller than those of COPD (P0.05); Din of asthma was larger than that of COPD (P0.05).     Conclusion    Bronchial remodeling in asthma and COPD patients manifests as bronchial wall thickening and luminal narrowing. Airway remodeling of asthma patients has both in segmental and sub-segmental bronchi

and airway remodeling of COPD patients is more apparent in sub-segmental bronchi.