Correlation between CT indices and spirometry in the COPD group
| FVC (% predicted) | FEV1 (% predicted) | FEV1/FVC | FEF25–75% | |
|---|---|---|---|---|
| Ai/BSA (apical) | – | – | – | – |
| WA% (apical) (%) | −0.32† | −0.32† | – | – |
| Ai/BSA (basal) | – | 0.26† | – | – |
| WA% (basal) (%) | – | – | – | – |
| Mean Ri (mm) | 0.28† | 0.39‡ | 0.29† | 0.36‡ |
| SD_Ri (mm) | – | – | −0.35‡ | – |
| SD_Ri /√BSA | – | – | −0.34‡ | – |
| CV_Ri | – | −0.40‡ | −0.42‡ | −0.29† |
−, not significant, †p<0.05, ‡p<0.01.
Ai, luminal area; BSA, body surface area; FEF25–75%, mean forced expiratory flow between 25% and 75% of FVC; Ri, radius of inscribed sphere in the airway lumen (see text); SD_Ri and CV_Ri, parameters for shape irregularity of the airway lumen (see text); WA%, percentage ratio of wall area to total airway area.