Lung ultrasound compared to computed tomography detection and automated quantification of systemic sclerosis-associated interstitial lung disease: preliminary study

Background: Lung ultrasound (LUS) is a promising tool for detecting SSc-Associated interstitial lung disease (SSc-ILD). Currently, consensus on the best LUS findings and execution technique is lacking. Objectives: To compare qualitative and quantitative assessment of B-lines and pleural line (PL) alterations in SSc-ILD with chest CT analysis. Methods: During 2021-2022, consecutive SSc patients according to 2013 ACR/EULAR classification criteria underwent pulmonary functional tests (PFTs). On the same day, if a CT was performed over a ± 6 months period, LUS was performed by two certified blinded operators using a 14-scans method. The ≥10 B-lines cut-off proposed by Tardella and the Fairchild's PL criteria fulfilment were selected as qualitative findings. As quantitative assessment, total B-lines number and the quantitative PL score adapted from the semi-quantitative Pinal-Fernandez score were collected. CT scans were evaluated by two thoracic radiologists for ILD presence, with further processing by automated texture analysis software (QCT). Results: Twenty-nine SSc patients were enrolled. Both qualitative LUS scores were significantly associated to ILD presence on CT, with Fairchild's PL criteria resulting in slightly more accuracy. Results were confirmed on multivariate analysis. All qualitative and quantitative LUS findings were found to be significantly associated with QCT ILD extension and radiological abnormalities. Mid and basal PL quantitative score correlated with mid and basal QCT ILD extents. Both B-lines and PL alterations differently correlated with PFTs and clinical variables. Conclusion: This preliminary study suggests the utility of a comprehensive LUS assessment for SSc-ILD detection compared with CT and QCT.