Lung ultrasound (LUS) for screening systemic sclerosis-associated interstitial lung disease (SSc-ILD): a radiation-free alternative?

Introduction To evaluate the diagnostic performance of lung ultrasound (LUS) in detecting interstitial lung disease (ILD) in patients with systemic sclerosis (SSc), as a radiation-free alternative to high-resolution CT (HRCT). Methods In this cross-sectional study, 18 adult participants with SSc underwent LUS and HRCT within 1 month as part of routine clinical care without previous knowledge of presence or absence of ILD. A 14-zone LUS protocol was applied and B-lines were quantified using two semiquantitative scoring systems. LUS results were compared with HRCT interpreted by a blinded thoracic radiologist. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated. Spearman correlation was used to evaluate the association between total B-line counts and HRCT severity. Results Of 18 participants, ILD was identified by HRCT in 72.2%. Using B-lines cut-off ≤5, LUS demonstrated 100% sensitivity, 40% specificity, 81% PPV and 100% NPV. Using B-lines cut-off ≤10, sensitivity was 92%, specificity 80%, PPV 92% and NPV 80%. B-line counts correlated strongly with HRCT severity (Spearman ρ=0.80, p<0.0001). Conclusion LUS shows high sensitivity and acceptable specificity for detecting ILD in SSc, particularly when using a higher B-line threshold. Future studies that incorporate LUS as an upfront screening tool are needed for validation of our findings.