Idiopathic pulmonary fibrosis: airway volume measurement identifies progressive disease on computed tomography scans

a) Specific airway volume change between computed tomography scans in an example patient. b) Median change in specific airway volume in the stable and progressive groups. The error bars represent the interquartile range and the bars themselves the median change. c) Correlation between absolute decline in forced vital capacity (FVC) (% predicted) with change in total specific airway volume.