Figure 1
From: Paired inspiratory-expiratory chest CT scans to assess for small airways disease in COPD
Inspiratory (A,C) and expiratory (B,D) chest CT images from two subjects with similar percent of lung voxels with attenuation values < −856HU on expiratory CT scans (Exp −856 ) demonstrate the inability of expiratory image analysis alone to distinguish gas trapping due to emphysema from gas trapping due to small airway disease. Subject 1: Exp−856 = 38.5%, percent emphysema (Insp−950) = 23.1%. Subject 2: Exp−856 = 37.1%, Insp−950 = 6.9%.