LUNG ULTRASOUND IN CHILDREN WITH CYSTIC FIBROSIS: A DESCRIPTIVE CLINICAL STUDY.

BACKGROUND: Longer life expectancy in cystic fibrosis (CF) has intensified concerns about cumulative radiation exposure from repeated imaging. High-resolution computed tomography (HRCT) remains essential for detecting deeper structural abnormalities, but there is growing interest in radiation-free tools capable of providing reliable and repeatable lung assessments. Lung ultrasound (LUS) has emerged as a promising adjunct technique, yet its role in routine paediatric CF follow-up and during pulmonary exacerbations remains incompletely defined. METHODS: We conducted a single-centre retrospective study including paediatric patients with CF who underwent LUS between 2021 and 2025. A standardised 12-zone protocol and a LUS score (0-36) were applied. LUS findings were correlated with clinical variables and lung function (Forced Expiratory Volume in one second, FEV1). Comparisons with chest radiography and HRCT were performed when available. In a subgroup, paired LUS examinations during pulmonary exacerbations were analysed. RESULTS: Thirty-five children were included (median age 10.0 years). LUS abnormalities were identified in 68% of patients, most frequently isolated B-lines and small subpleural consolidations. No significant differences in lesion distribution were observed across anatomical regions. The LUS score showed a strong negative correlation with FEV1% predicted (ρ = -0.655, p < 0.001) and was associated with BMI z-score (ρ = -0.694, p < 0.001) and exacerbation burden (ρ = 0.431, p = 0.010). Children receiving CFTR modulator therapy had significantly lower LUS scores (p = 0.021). Compared with chest radiography, LUS detected additional abnormalities in 27% of examinations with apparently normal radiographs. LUS reliably identified all clinically relevant consolidations detected in CT, but CT remained superior for proximal lesions, which are not accessible by LUS. In the exacerbation subgroup, LUS could track real-time disease evolution. CONCLUSION: LUS is a practical, repeatable, and radiation-free point-of-care imaging tool that offers clinically relevant information in children with CF. It correlates with functional impairment, detects abnormalities not visible on radiography, and may support monitoring during exacerbations. While CT remains essential for complete structural assessment, LUS may help reduce unnecessary radiographic exposure and extend CT surveillance intervals, positioning it as a valuable complementary tool in modern CF care.