Lung Ultrasonography for Detection of Interstitial Lung Disease in Patients with Systemic Sclerosis – A Diagnostic Accuracy Study

<bold>Background:</bold> Systemic sclerosis (SSc) heightens the risk of interstitial lung disease (ILD). High-resolution computer tomography (HRCT) stands as the gold standard; its utility is constrained by cost and availability. Lung ultrasonography (LUS) has emerged as a radiation-free alternative to evaluation. This study aims to assess LUS accuracy, and establish correlations with HRCT features in SSc-ILD. <bold>Methods:</bold> This prospective cohort, diagnostic accuracy study compared SSc-ILD and non-ILD patients. ILD presence was determined by HRCT, with exclusion criteria covering pulmonary edema or infection. LUS was conducted within 3 months of HRCT by a pulmonary fellow in 14 areas for both groups. LUS videos underwent blind interpretation by a pulmonologist. <bold>Results:</bold> Of the 21 enrolled patients, 15 had SSc-ILD. The mean age of SSc-ILD patients is 51±11 years. Baseline PFTs didn't differ between 2 groups. LUS abnormalities, defined by (a) B-lines ≥3 lines with pleural abnormalities, were significantly higher in SSc-ILD than the control (5.9±3.3 vs. 0.3±0.8 area, p < 0.001), and (b) B-lines ≥3 lines with pleural abnormalities in 2 consecutive areas were significantly higher in SSc-ILD than the control (3.6±3.3 vs. 0 pairs, p 0.000). The sensitivity, specificity, and AUC of LUS parameter (a) were 86.7%, 83.3%, and 0.850, respectively, and parameter (b) were 86.7%, 100%, and 0.933, respectively. Both LUS parameters strongly correlated with the HRCT Well score, (a) r 0.709, p = 0.011, and (b) r 0.672, p = 0.033. <bold>Conclusion:</bold> Combining LUS abnormalities by at least 3 B-lines with associated pleural irregularities in 2 consecutive areas has high accuracy for diagnosing SSc-ILD.