Abstract
BACKGROUND: Interstitial lung disease (ILD) is a serious complication of connective tissue disease (CTD) with significant morbidity and mortality. Lung ultrasound (LUS) has been widely used in the diagnosis of a variety of lung diseases. However, there is no standard ultrasound scanning method or scoring method for connective tissue disease associated with interstitial lung disease (CTD-ILD); therefore, it is necessary to establish a set of standard evaluation methods. METHODS: A total of 60 consecutive patients with clinically confirmed CTD and suspected ILD were prospectively included in this study. LUS and high-resolution computed tomography (HRCT) were used to examine all patients. The time between HRCT and LUS examinations was less than 2 weeks. The ultrasonographic results were evaluated with the modified scoring method and the Buda scoring method. The imaging results were evaluated with the HRCT Warrick scoring method. The primary aim was to evaluate the diagnostic value of a modified ultrasound scoring method in CTD-ILD. RESULTS: The results of the Youden index for the diagnosis of CTD-ILD by the modified method, the Buda method, and the HRCT method were 0.845, 0.711, and 0.911, respectively, with areas under the receiver operating characteristic (ROC) curve (AUC) of 0.982 [95% confidence interval (CI): 0.945-1.000], 0.950 (95% CI: 0.851-0.990), and 0.985 (95% CI: 0.949-1.000), respectively. With a clinical diagnosis as the gold standard, the consistency of the modified method and the HRCT method for CTD-ILD was high (Kappa values =0.872 and 0.913, respectively). The values of the modified method and the Buda method consistently and significantly increased with the increasing severity of CTD-ILD. For the former, there were significant differences between the mild, moderate, and severe groups (P<0.05). The ROC curve used to calculate the modified ultrasound score predicted the critical values of mild and severe pulmonary fibrotic lesions at 34 points (sensitivity, 100%; specificity, 92.9%; AUC =0.933; 95% CI: 0.807-1.000) and 64.5 points (sensitivity, 92.0%; specificity, 85.3%; AUC =0.972; 95% CI: 0.929-1.000). CONCLUSIONS: The modified ultrasound method has a higher diagnostic value than the Buda method for CTD-ILD.