Correlation Between CT-Derived Bhalla Score and Lung Ultrasound Score in Adult Patients with Cystic Fibrosis

Background/Objectives: Cystic fibrosis is a chronic multisystem disease in which pulmonary involvement is the main determinant of morbidity and mortality. Chest computed tomography is the reference standard for assessing structural lung damage, but its repeated use is limited by cumulative radiation exposure. Lung ultrasound has emerged as a radiation-free alternative; however, its role in adult patients remains incompletely defined. This study aimed to evaluate the correlation between CT-derived structural lung damage and ultrasound findings, and to assess the complementary role of these imaging modalities. Methods: A prospective cohort study was conducted including adult patients with cystic fibrosis who underwent both chest computed tomography and lung ultrasound during the same clinical episode. Structural lung involvement was assessed using the Bhalla score, while lung aeration was evaluated using the Lung Ultrasound Score. Correlation analyses, severity stratification, regression modeling, and longitudinal comparisons were performed. Results: Thirteen patients contributed 24 imaging evaluations. A strong positive correlation between Bhalla score and ultrasound findings was observed in the cross-sectional analysis and remained consistent when all examinations were included. Ultrasound scores increased significantly across CT-defined severity groups, and regression analysis confirmed a significant association between the two methods. Exploratory analysis showed stronger associations for peripheral and aeration-related abnormalities, while weaker associations were observed for deeper airway changes. No significant correlation was identified in longitudinal analysis. Conclusions: Lung ultrasound correlates well with CT-derived structural lung damage and may serve as a complementary, radiation-free tool for disease assessment in adult cystic fibrosis. However, its limited sensitivity in detecting temporal changes highlights the continued importance of CT in selected clinical scenarios.