A Preliminary Study on the Relationship Between High-resolution Computed Tomography and Lung Function in People at Risk of Developing Chronic Obstructive Pulmonary Disease

Background: There is high morbidity and mortality for patients with chronic obstructive pulmonary disease (COPD) in China. The aim of our study was to explore the differences in high-resolution computed tomography (HRCT) emphysema parameters, air trapping parameters, and lung density parameters between patients at high risk and low risk of developing COPD and evaluate their correlation with lung function indicators.Methods: In this retrospective, single-center cohort study, we enrolled outpatients from the Physical Examination Center and Respiratory Medicine of The First Affiliated Hospital of Wenzhou Medical University. The patients at risk of developing COPD were ≥40 years-old, had chronic cough or sputum production, and/or had exposure to risk factors for the disease and had not reached the diagnostic criteria. Patients were divided into a low-risk group and high-risk group according to FEV1/FVC≥80% and 80%>FEV1/FVC≥70%. The data on clinical characteristics, clinical symptom score, lung function, and HRCT were recorded.Results: 72 COPD high-risk patients and 86 COPD low-risk patients were enrolled in the study, and the air trapping index of the left, right, and bilateral lungs of the high-risk group were significantly higher than those of the low-risk group . Additionally, the mean lung density during expiration was significantly lower than that of the low-risk group. The emphysema index of left, right, and bilateral lungs was negatively correlated with FEV1/FVC (correlation coefficients were -0.33-0.22-0.26). There was a negative correlation between the air trapping index of left and right lungs and bilateral lungs and FEV1/FVC(correlation coefficients were -0.33-0.23-0.28, respectively), and the mean expiratory lung density of left and right lungs and bilateral lungs was positively correlated with FEV1/FVC (correlation coefficients were 0.31, 0.25, 0.29, respectively).Conclusions: The air trapping index and the mean expiratory lung density obtained by HRCT combined with post-processing technology can be used as a basis for distinguishing between people at high risk and low risk for developing COPD. Emphysema index, air trapping index, and mean expiratory lung density shows significantly negative correlation with FEV1/FVC, and this can be used to assess the pulmonary function status of people at risk of developing COPD.