Fig. 2

CT quantification of emphysema and pulmonary vessels. A CT coronal reconstructed image of a 54-year-old male with COPD GOLD grade 1 reveals centrilobular and paraseptal emphysema. B The emphysema was measured using a threshold of -950HU (shown in green; LAA-950, 12.3%). C Pulmonary vessels are automatically extracted and segmented (shown in red; Ntotal/LSA, 1.05; N5mm/LSA, 0.97), and the green contours show the lung surface area at 6 mm from the pleural surface. CT computed tomography, LAA low attenuation area