Comparison Of Application Value Of Different Threshold Segmentation Methods In Quantitative Evaluation Of Connective Tissue Disease Associated Interstitial Lung Disease

Objective:To compare the application of multiple previously defined quantitative lung assessment methods based on threshold segmentation in connective tissues disease—interstitial lung disease(CTD-ILD),and to explore the best method for assessing disease severity.Methods:A total of 194 cases of CTD-ILD from January 1,2018 to January 1,2021 in Bethune Hospital of Shanxi were retrospectively analyzed,after screening,142 cases were included.Interstitial lung disease(ILD)scores(including semi-quantitative visual scores)and ILD severity(such as localized or diffuse)were calculated.Five known threshold intervals were set as lung interstitial changes and volume percentage was calculated.Correlation analysis was used to evaluate the correlation between quantitative scores of five methods and lung function parameters or semi-quantitative visual scores respectively,and the best method was obtained.By drawing receiver Operating characteristic curve(ROC),the Youden index was selected as the best diagnostic point,and the sensitivity and specificity of each method for the diagnosis of disease severity were calculated.Results:For assessment methods of CTD-ILD based on lung tissue threshold segmentation,there was a correlation between all methods and semi-quantitative visual assessment results(P<0.05).Among the results of quantitative correlation analysis,when the threshold range of interstitial change was set as-600 HU～-260 HU and the threshold range of total lung volume was set as-950 HU～-200 HU,the obtained quantitative indexes were most closely related to the lung function of patients(Composite physiologic index(CPI): r=0.482,P<0.01;Carbon monoxide diffusing capacity(DLCO)as a percentage of the estimated value: r=-0.424,P<0.01)and the staging of disease efficacy was best(AUC=0.735,95%CI: 0.655～0.816).Conclusion:Quantitative lung assessment based on threshold segmentation is a possible alternative to objectively evaluation of the semi-quantitative visual score of CTD-ILD,and has important implications for distinguishing between localized and diffuse ILD.When-600～-260 HU was set as the range of interstitial changes,it had the best correlation with lung function,which could better reflect the physiological characteristics of CTD-ILD.