Characteristics of baseline quantitative CT assessments of subjects
| Mean (SD) | Range | |
| Total lung volume(ml) | 5086.2 (1350.3) | 2608.1–9861.1 |
| Mean lung density (g/ml) | 0.2 (0.0) | 0.1–0.2 |
| Lung overinflation | ||
| %overinflation | 58.4 (16.4) | 15.9–83.7 |
| Cluster analysis | 1.5 (0.2) | 1.2–2.1 |
| Upper zone predominant | n = 102 | |
| Diffuse distribution | n = 7 | |
| Lower zone predominant | n = 34 | |
| Emphysema | ||
| %LAA(−950 HU) | 2.9 (2.6) | 0.2–13.3 |
| Cluster analysis | 3.1 (0.4) | 2.1–4.4 |
| Upper zone predominant | n = 35 | |
| Diffuse distribution | n = 10 | |
| Lower zone predominant | n = 98 | |
| Airway dimensions | ||
| Lumen area, Ai (mm2) | 6.8 (2.3) | 2.1–15.1 |
| WA % | 76.8 (3.5) | 67.5–84.9 |
| √Aaw at Pi10 (mm) | 4.4 (0.2) | 3.9–5.1 |
Aaw, airway wall area; Ai, lumen area; LAA, low attenuation lung area; Pi, lumen perimeter; WA %, wall area expressed as the percentage of the total airway area.
%overinflation, (volume of overinflated lung/volume of total lung) × 100%; %LAA (−950 HU), (volume of lung areas with x ray attenuation lower than −950 HU/volume of total lung) × 100%; WA%, (airway wall area/(airway wall area + lumen area))×100%; √Aaw at Pi10 (mm), √Aaw for a standardised airway with an internal perimeter (ie, Pi) of 10 mm.