title: Sagittal-lung CT measurements in the evaluation of asthma-COPD overlap syndrome: a distinctive phenotype from COPD alone.
abstract: OBJECTIVE
  This study aimed at investigating the capability of sagittal-lung computed tomography (CT) measurements in differentiating chronic obstructive pulmonary disease (COPD) and asthma-COPD overlap syndrome (ACOS).
  
  
  METHODS
  Clinical and high-resolution CT of 229 patients including 123 pure COPD patients and 106 ACOS patients were included. Sagittal-lung CT measurements in terms of bilateral lung height (LH), anterior-posterior lung diameter (APLD), diaphragm height (DH), and anterior sterno-diaphragmatic angle (ASDA), as well as inter-pulmonary septum length (IPSL) on axial images were measured both before and after bronchodilator (BD) administration. Comparisons of clinical characteristics and CT measurements between patient groups were performed.
  
  
  RESULTS
  All pre-BD quantitative sagittal features measuring diaphragm flattening and hyperinflation were not significantly different between patients with COPD and patients with ACOS (P values all >0.05). Following BD administration, the ACOS patients exhibited lower left LH, bilateral APLD, and bilateral ASDA, but higher right DH, compared to pure COPD patients (P values all <0.05). Right LH, left DH and IPSL were not significantly different between patient groups. Besides, variations of all sagittal-lung CT measurements were significantly larger in patients with ACOS than in patients with pure COPD (P values all <0.001) and showed high performance in differentiating these two kinds of patient, with diagnostic sensitivities ranging from 76.4 to 97.2%, specificities ranging from 86.2 to 100.0%, and accuracies ranging from 80.9 to 90.7%.
  
  
  CONCLUSIONS
  Sagittal-lung CT measurements allow for differentiating patients with ACOS from those with pure COPD. The ACOS patients had larger post-BD variations of sagittal-lung CT measurements than patients with pure COPD.
authors.affiliation: Department of Radiology, Zhongnan Hospital of Wuhan University, No. 169 East Lake Road, Wuchang District, Wuhan, 430071, Hubei Province, People's Republic of China.
authors.forename: Yanjuan
authors.initials: Y
authors.lastname: Qu
authors.affiliation: Department of Radiology, Zhongnan Hospital of Wuhan University, No. 169 East Lake Road, Wuchang District, Wuhan, 430071, Hubei Province, People's Republic of China.
authors.forename: Yiyuan
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Department of Radiology, Zhongnan Hospital of Wuhan University, No. 169 East Lake Road, Wuchang District, Wuhan, 430071, Hubei Province, People's Republic of China. liaomy@whu.edu.cn.
authors.forename: Meiyan
authors.initials: M
authors.lastname: Liao
authors.affiliation: Department of Radiology, Zhongnan Hospital of Wuhan University, No. 169 East Lake Road, Wuchang District, Wuhan, 430071, Hubei Province, People's Republic of China. luzhiyan@whu.edu.cn.
authors.forename: Zhiyan
authors.initials: Z
authors.lastname: Lu
mesh_terms: D001249:Asthma / Q000000981:diagnostic imaging* / Q000188:drug therapy; D001993:Bronchodilator Agents / Q000008:administration & dosage; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000188:drug therapy; D013902:Radiography, Thoracic; D012129:Respiratory Function Tests; D012680:Sensitivity and Specificity; D013577:Syndrome; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D001993:Bronchodilator Agents
keywords: Asthma-COPD overlap syndrome (ACOS); Chronic obstructive pulmonary disease (COPD); Computed tomography (CT)