Fig. 1. An example of emphysema and AT composite. A-F: Axial (A) and coronal (B) chest CT images of a patient with asthma are shown. Axial (C) and coronal (D) images with an overlay of the density mask (shown in different colors, indicating areas of AT without emphysema, AT with emphysema, emphysema without AT, and normal), allowing a robust assessment of AT. The results of the analysis (E) provide the percentage volume (relative to the total lung volume) of the aforementioned four areas. The EAtC map (F) displays various colors corresponding to different voxel volumes (indicated by the color bar), correlating with the Hounsfield units of inspiration on the y-axis and the subtraction value of co-registered image on the x-axis. fAT = functional air trapping, EAtC = emphysema air-trapping composite.