Visual and Quantitative Assessments of Regional Xenon-Ventilation Using Dual-Energy CT in Asthma-ChronicObstructive Pulmonary Disease Overlap Syndrome:A Comparison with Chronic Obstructive PulmonaryDisease

ABSTRACT

Objective@#To assess the regional ventilation in patients with asthma-chronic obstructive pulmonary disease (COPD) overlapsyndrome (ACOS) using xenon-ventilation dual-energy CT (DECT), and to compare it to that in patients with COPD. @*Materials and Methods@#Twenty-one patients with ACOS and 46 patients with COPD underwent xenon-ventilation DECT. Theventilation abnormalities were visually determined to be 1) peripheral wedge/diffuse defect, 2) diffuse heterogeneous defect,3) lobar/segmental/subsegmental defect, and 4) no defect on xenon-ventilation maps. Emphysema index (EI), airway wallthickness (Pi10), and mean ventilation values in the whole lung, peripheral lung, and central lung areas were quantified andcompared between the two groups using the Student’s t test. @*Results@#Most patients with ACOS showed the peripheral wedge/diffuse defect (n = 14, 66.7%), whereas patients with COPDcommonly showed the diffuse heterogeneous defect and lobar/segmental/subsegmental defect (n = 21, 45.7% and n = 20,43.5%, respectively). The prevalence of ventilation defect patterns showed significant intergroup differences (p< 0.001). Thequantified ventilation values in the peripheral lung areas were significantly lower in patients with ACOS than in patients withCOPD (p= 0.045). The quantified Pi10 was significantly higher in patients with ACOS than in patients with COPD (p= 0.041);however, EI was not significantly different between the two groups. @*Conclusion@#The ventilation abnormalities on the visual and quantitative assessments of xenon-ventilation DECT differed betweenpatients with ACOS and patients with COPD. Xenon-ventilation DECT may demonstrate the different physiologic changes ofpulmonary ventilation in patients with ACOS and COPD.