Quantitative Assessment Of Connective Tissue Disease-associated Interstitial Lung Disease By HRCT

Objective: This study aims to explore the diagnostic ability and evaluation power of different lung quantitative assessment methods based on high resolution computed tomography(HRCT)density threshold method,density histogram method and comprehensive analysis method for the severity of patients who suffered from connective tissue disease(CTD)-associated interstitial lung disease(ILD).Methods: A retrospective analysis was performed in CTD-ILD patients who underwent continuous HRCT chest scan and pulmonary function test(PFT).Two radiologists used Goh score and Camiciottoli score to visually semi-quantitatively score ILD severity on HRCT,and grouped the severity of ILD(limited group or extensive group)by a 20% Goh score threshold and a 70% forced vital capacity(FVC%)threshold.The quantitative indexes based on HRCT density threshold method and density histogram method were recorded and the new index computerized integrated index(CII)was calculated by principal component analysis.The t test or MannWhitney U test was selected to contrast the differences of each parameter between the limited group and the extensive group.One-way analysis of variance(ANOVA)or Kruskal-Wallis H-test was used for comparing the differences among different CTD types.The correlation among variables was evaluated by Spearman correlation test.The ability of different lung quantitative evaluation methods was analyzed by ROC curve,to distinguish the severity of CTD-ILD.Results: 93 patients were included in the study,containing 42 patients(45.16%)in the limited group and 51 patients(54.84%)in the extensive group.The results showed that the differences of quantitative HRCT indexes,visual semi-quantitative scores and PFT parameters were statistically significant between the limited group and the extensive group(P<0.05).Except MLA-4 and DLCO%,there were significant correlations among HRCT quantitative indexes,visual semi-quantitative scores and PFT parameters.ROC analysis showed that CII-4 and CII-5 had the strongest ability to distinguish ILD severity,with AUCs of 0.886(95%CI 0.813-0.959)and 0.883(95%CI0.807-0.958),respectively.Conclusion: The quantitative methods based on HRCT density threshold method,density histogram method and comprehensive analysis method provide objective indicators for evaluating the severity of lung function impairment in CTD-ILD patients,which have potential important significance for distinguishing extensive CTD-ILD patients with poor prognosis,and can be used as a potential alternative to visual semiquantitative scoring method.