title: Airway Measurement for Airway Remodeling Defined by Post-Bronchodilator FEV1/FVC in Asthma: Investigation Using Inspiration-Expiration Computed Tomography.
abstract: OBJECTIVE
  Airway remodeling may be responsible for irreversible airway obstruction in asthma, and a low post-bronchodilator FEV1/FVC ratio can be used as a noninvasive marker of airway remodeling. We investigated correlations between airway wall indices on computed tomography (CT) and various clinical indices, including post-bronchodilator FEV1/FVC ratio, in patients with asthma.
  
  
  METHODS
  Volumetric CT was performed on 22 stable asthma patients who were taking inhaled corticosteroids. Airway dimensions were measured at four segmental bronchi using in-house software based on the full-width/half-maximum method. Parameters included luminal area, wall thickness (WT), wall thickness percentage (WT%), wall area percentage (WA%), bronchial-to-arterial diameter (BA) ratio on inspiration CT, airway collapsibility (AC), and air trapping index (ATI). Correlations were analyzed between CT parameters and clinical indices, including %FEV1, FEV1/FVC, FEF(25-75%), and post-bronchodilator FEV1/FVC ratio.
  
  
  RESULTS
  Post-bronchodilator FEV1/FVC showed significant correlations with WT%, WT, BA ratio, AC, and ATI (r=-0.503, -0.576, 0.454, 0.475, and -0.610, respectively). WT showed negative correlations with FEV1/FVC and FEF(25-75%) (r=-0.431 and -0.581), and WT% was negatively correlated with %FEV1, FEV1/FVC, and FEF(25-75%) (r=-0.434, -0.431, and -0.540, respectively). WA% showed correlations with FEF(25-75%) and body mass index (r=-0.459 and 0.453). The BA ratio was positively correlated with %FEV1 (r=0.459) and FEF(25-75%) (r=0.479). AC showed strong positive correlation with FEV1/FVC (r=0.592), and ATI showed negative correlations with FEV1/FVC (r=-0.534) and FEF(25-75%) (r=-0.591).
  
  
  CONCLUSIONS
  WT%, WT, BA ratio, and AC on inspiration and expiration CT are good indices for measuring airway remodeling defined by post-bronchodilator FEV1/FVC in stable asthma patients treated with inhaled corticosteroids.
authors: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors: Eun Jin
authors: EJ
authors: Chae
authors: Tae-Bum
authors: TB
authors: Kim
authors: You Sook
authors: YS
authors: Cho
authors: Chan-Sun
authors: CS
authors: Park
authors: Joon Beom
authors: JB
authors: Seo
authors: Namkug
authors: N
authors: Kim
authors: Hee-Bom
authors: HB
authors: Moon