Evaluation of non-invasive techniques for the diagnosis of pulmonary complications in systemic sclerosis and scleroderma-like overlap syndromes: role of lung ultrasound

Background and aim: Pulmonary arterial hypertension (PAH) and interstitial lung disease (ILD) are the leading cause of death in Systemic Sclerosis (SSc) and severely affect patients’ quality of life. Early, accurate, and non-invasive diagnostic tools are essential for timely treatment. This study investigates the role of lung ultrasonography (LUS) as a screening method for detecting pulmonary involvement in SSc. Methods: A monocentric cross-sectional study was conducted on 72 patients diagnosed with SSc. Lung ultrasound was performed using a 1–5 MHz convex probe across 14 lung fields. B-lines were quantified using the Total Thoracic Ultrasound Score (TTUS). Echocardiographic data, pulmonary function tests, and visual score on high resolution computed tomography (HRCT) were also collected. Results: TTUS scores showed significant correlation with the presence of ILD and PAH (p = 0.001). TTUS positively correlated with pulmonary arterial pressure, Goh score, visual HRCT score, and inversely correlated with DLCO and 6-min walk test performance. LUS demonstrated good diagnostic performance: fewer than 6 B-lines ruled out PAH with 100% sensitivity (specificity 38.8%; AUC 0.77 [0.64–0.90]). The presence of fewer than 5 B-lines excluded ILD with 100% sensitivity. Conversely, more than 15 B-lines indicated ILD (sensitivity 88.9%; specificity 82.5%; accuracy 91.4%; AUC 0.88 [0.79–0.97]). Conclusions: LUS is a reliable, non-invasive tool for detecting pulmonary involvement in SSc: its high negative predictive value allows it to be adopted as a first-line imaging to rule out PAH and ILD.