Lung Ultrasound in Cystic Fibrosis: A Systematic Review of Clinical Utility, Scoring Systems, and Correlation With Structural and Functional Outcomes.

Background lung ultrasound (LUS) has emerged as a potential radiation-free imaging modality for the evaluation of cystic fibrosis (CF) lung disease. However, its clinical utility, the role of CF-specific LUS scoring systems, and correlations with structural and functional outcomes remain incompletely defined. The objective of this review was to systematically evaluate the role of LUS in cystic fibrosis, with particular focus on CF-specific scoring systems, diagnostic performance, and correlations with imaging and functional disease severity. A systematic search of PubMed and Web of Science was conducted for studies published between January 2016 and January 2026 evaluating LUS in individuals with cystic fibrosis. Prospective and retrospective observational studies assessing LUS findings, scoring systems, or clinical outcomes were included. Screening, data extraction, and risk-of-bias assessment were performed independently by two reviewers in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 recommendations. Due to heterogeneity in study design, ultrasound protocols, and outcomes, results were synthesized qualitatively. Nine studies involving 390 individuals with cystic fibrosis met the inclusion criteria, with most cohorts consisting predominantly of pediatric patients. Four studies developed CF-specific LUS scoring systems, while others applied existing or non-CF-specific scores or descriptive protocols. LUS consistently detected peripheral abnormalities, such as subpleural consolidations, pleural irregularities, and interstitial patterns, and frequently identified lesions not visible on chest radiography. CF-specific LUS scores demonstrated strong correlations with computed tomography (CT) structural severity, spirometry, and lung clearance index (LCI), particularly in patients with moderate-to-advanced disease. Correlations were weaker in cohorts with predominantly mild disease or when non-CF-specific scoring systems were used. LUS showed limited sensitivity for central airway pathology, including bronchiectasis and mucus plugging. LUS is a feasible, radiation-free imaging modality capable of detecting and monitoring peripheral lung disease in cystic fibrosis, particularly when CF-specific scoring systems are applied. While it cannot replace CT for comprehensive structural evaluation, LUS may serve as a valuable complementary tool for longitudinal monitoring. Further standardization and multicentre longitudinal studies are required to define its role in routine CF care.