Real-Time Imaging of Lower Airway Collapse at 0.55T

Motivation: Tracheomalacia involves intermittent collapse of the lower airway and is difficult to diagnose. Currently, this condition is evaluated with invasive procedures like bronchoscopy or dynamic computer tomography (CT) which utilizes ionizing radiation. Goal(s): To develop and optimize a high spatial and temporal resolution pulse sequence for evaluating tracheomalacia at 0.55T. Approach: We optimize contrast (sequence, flip angle) for dynamic imaging in the lower airway for both 2D and SMS real-time imaging. Results: Spiral acquisition achieves sufficient temporal resolution and the TrueFISP sequence (flip angle=32°) offers optimal contrast for imaging lower airway collapse. Impact: We demonstrate the feasibility of capturing lower airway collapse with 2D and SMS real-time imaging (at 0.55T) in a way that is informative to the diagnosis and longitudinal monitoring of tracheomalacia.