Lung ultrasound versus high-resolution computed tomography in the longitudinal monitoring of interstitial lung disease: a prospective cohort study in systemic sclerosis.

BACKGROUND: Interstitial lung disease (ILD) constitutes the primary cause of mortality in patients with systemic sclerosis (SSc), necessitating precise radiographic monitoring to facilitate treatment decisions and improve prognosis. Lung ultrasound (LUS) shows promise for ILD screening, but its long-term effectiveness in tracking ILD change remains undetermined. METHODS: A total of 131 SSc patients were enrolled in this single-center prospective study, of whom 83 completed the longitudinal follow-up with both LUS and high-resolution computed tomography (HRCT). LUS was performed across 72 intercostal spaces using a semi-quantitative scoring system; total LUS score summed all zones. Improvement or progression was defined as an absolute reduction or increase of ≥5% in the extent of ILD on HRCT. RESULTS: The baseline LUS score correlated highly with ILD extent on HRCT (Spearman's Rho = 0.9087, P < 0.0001). Follow-up data indicated that changes in LUS score (ΔLUS) closely align with alterations in ILD extent on HRCT (ΔHRCT) (Spearman's Rho = 0.9046, P < 0.001), with ΔLUS score serving as a significant predictor of ΔHRCT (β = 0.535, P < 0.001). The ΔLUS score was identified as a significant predictor for ILD progression (OR = 1.874, P = 0.003) or improvement (OR = 0.821, P < 0.001). Specifically, an increase in LUS scores greater than 5 points predicted ILD progression (AUC = 0.98), while a decrease greater than 4 points predicted ILD improvement (AUC = 0.94). CONCLUSIONS: LUS, as a non-invasive, repeatable tool, shows clinically relevant potential for identifying radiographic progression or improvement in SSc-associated ILD (SSc-ILD).