Assessment of Central Airways Mechanics Using Dynamic Magnetic Resonance Imaging (Cine‐MRI): A Comparison to Flexible Bronchoscopy

Background: Flexible bronchoscopy (FOB) is the current gold standard for diagnosing tracheobronchomalacia (TBM). While dynamic magnetic resonance imaging (cine-MRI) has emerged as a radiation-free alternative for TBM diagnosis, a direct comparison of its diagnostic performance with FOB has not yet been performed. Objective: This study aimed to evaluate the diagnostic performance of cine-MRI versus FOB in detecting TBM and to assess the effect of bronchodilators on observed tracheobronchial collapse. Methods: The study included 10 children (median age 11 years, range 8–17 years; five males) who were referred for suspected TBM. Cine-MRI was performed using a 3 Tesla GE 750 W scanner with specific sequences for static and dynamic imaging. Bronchodilator testing was conducted using 400 µg salbutamol. Children suspected of TBM underwent both FOB and cine-MRI. Cine-MRI protocol included spirometry-controlled static and dynamic sequences, pre- and post-bronchodilator administration. FOB diagnoses were made by pediatric pulmonologists, and cine-MRI assessments were independently evaluated by two trained observers, blinded to FOB results. Moreover, each child completed spirometry and a respiratory questionnaire. Descriptive statistics were used to summarize data. Diagnostic agreement and measurements repeatability were assessed using the intra-class correlation coefficient (ICC). Results: FOB identified TBM in two children, whereas cine-MRI detected TBM in four. In three of these four children TBM was not diagnosed by FOB. Notably, no TBM was observed during static pre-bronchodilator cine-MRI assessment, but two of the four children diagnosed with cine-MRI met the diagnostic criteria of TBM only post-bronchodilation. Conclusion: Cine-MRI, particularly post-bronchodilation shows a unique capability to detect TBM cases undetected by FOB. This may reflect its ability to perform dynamic functional measurements during active respiratory maneuvers, highlighting its potential as a valuable diagnostic tool for central airway disease in children.