Hyperpolarized 129Xe Gas Exchange MRS in Mice: Impact of Heart Rate, Ventilation Pressure, and a Paralytic on Cardiogenic Signal Oscillations

Motivation: Upon dissolution into pulmonary tissues, hyperpolarized 129Xe shifts frequency, providing a window into gas-exchange dynamics. Because mice lack a unique RBC peak, the feasibility of harnessing this novel contrast has not yet been investigated. Goal(s): To demonstrate dissolved 129Xe cardiogenic oscillations in mice for the first time. Approach: 129Xe magnetic resonance spectroscopy was applied under a range of anesthesia, ventilation, and heart rate conditions to establish a normal physiological baseline. Results: Oscillations amplitude is strongly correlated with heart rate and sensitive to capillary hemodynamics. With proper animal handling, 129Xe MRS represents a promising method to assess cardiopulmonary pathophysiology in mouse models. Impact: 129Xe dissolved into tissue displays one peak in mouse lungs. Despite lacking a unique RBC peak, cardiogenic oscillations are observed via MRS. Oscillation amplitude is sensitive to lung hemodynamics and represents a promising means to noninvasively assess pathology in mice.