Analysis of relationship between the severity of chronic obstructive pulmonary disease and pulmonary function based on different threshold analysis of expiratory phase / 中国医学影像技术

ABSTRACT

Objective: To analyze the impact of the percentage of low attenuation area (LAA) in total lung volume (LAA%-950, LAA%-910, LAA%-856) with threshold lower than -856 HU, -910 HU and -950 HU on the severity of chronic obstructive pulmonary disease (COPD) in deep end expiratory CT scan, and to explore the correlations between quantitative indicators and pulmonary function. Methods: CT images in deep expiratory and clinical lung function data of 104 COPD patients were collected. The patients were divided into 4 groups according to global initiative for chronic obstructive lung disease (GOLD) guidelines. Then data were imported into the "digital lung" detection and analysis platform, and the mean lung density in expiratory phase (MLDex) and LAA%-950, LAA%-910, LAA%-856 were calculated. Pulmonary function indicators, including forced vital capacity (FVC), forced vital capacity expressed as percent predicted (FVC%), forced expiratory volume in 1 second expressed as percent predicted (FEV1%), FEV1/FVC, carbon monoxide diffusion capacity expressed as percent predicted (DLCO%), carbon monoxide diffusion capacity corrected for alveolar volume (DLCO/VA) and residual volume to total lung capacity ratio (RV/TLC) were obtained. CT quantitative parameters and pulmonary function indexes were compared among 4 groups, and correlations of CT quantitative parameters and lung function were analyzed. Multiple stepwise regression analysis was performed to observe the relationships of LAA%-950, LAA%-910, LAA%-856 and MLDex. Results: LAA%-950, LAA%-910 and MLDex were statistically significant among 4 groups (all P<0.01). LAA%-910 was negatively correlated with FVC, FVC%, FEV1%, FEV1/FVC, DLCO% and DLCO/VA, and positively correlated with RV/TLV. MLDex was negatively correlated with LAA%-950, LAA%-910 and Using LAA%-856. LAA%-950, LAA%-910 and MLDex could introduce a regression equation with R2=0.917 (P<0.01). Conclusion: Expiratory CT quantitative index LAA%-910 be used to accurately assess the severity of COPD and has good correlation with pulmonary function.