Detailed analysis of the density change on chest CT of COPD using non-rigid registration of inspiration/expiration CT scans

This study aimed to evaluate air trapping index (ATI) measured by CT in COPD patients and nonsmokers, and its association with pulmonary function test (PFT) parameters. The study included 138 COPD patients and 29 nonsmokers. Results showed that COPD patients had higher ATI values in the whole lung and specific lung lesions compared to nonsmokers. ATI demonstrated stronger correlations with PFT parameters such as FEF25-75%, RV, and RV/TLC compared to the emphysema index (EI). ATI also showed similar correlations to other CT parameters like gas trapping index and expiration/inspiration ratio of mean lung density. Additionally, ATI in emphysema and hyperinflated areas on CT had better correlations with PFT parameters than the normal lung area. The study suggests that analyzing density changes in different lung areas using CT can provide valuable insights into the pulmonary functional impairment seen in COPD patients. The analysis method have been comercialized in AVIEW COPD, Coreline Soft