Murine Lung Acoustics: Simulating Airway Insonification and Magnetic Resonance Elastography

Lung diseases are common and in some case can be fatal. Some of them affect the structure and mechanical properties of lung tissues in different and unique ways. Mice have been used as models of lung pathology. In this study, a computational model, based on medical images, is developed to compare the murine airway structure and how its acoustic properties are altered for the case of lung fibrosis, resulting in increased tissues stiffness, and asthma, which means bronchoconstriction or a reduction in airways diameter, as compared to the healthy case. Furthermore, the computational model is used to simulate magnetic resonance elastography (MRE) of the murine airways. MRE is a remote palpation technique which takes advantage of how propagation of mechanical vibrations is altered in biological tissues when the structural and mechanical properties of the tissue are altered. Adaption of the airway modeling and acoustic simulation from humans to mice is uniquely challenging, given the substantial size difference. After the creation of a 3D model using ITK-snap and a tracing tree in Matlab, the model is integrated into the branching 1D waveguide (a Matlab code) for acoustic simulations, properly modified to be used for imaging data taken from a mouse. The mechanical properties of the tissue are modified for different case studies, and outputs of interest are the acoustic pressure in the airways and the associated airway wall radial velocity. While most of the results follow expected trends, some challenges in modeling remain.