Comprehensive Pulmonary Evaluation of Emphysematous Mice using Hyperpolarized Xe MRI/MRS under Spontaneous Breathing Mode

Introduction: Hyperpolarized (HP) noble gas MRI and MRS in the lungs on spontaneous breathing mice is expected as a valuable modality for drug discovery or development of the methods for evaluating physiological changes. Since the measurements under the spontaneous breathing condition are fully non-invasive protocol without using mechanical ventilation, this technique allows a long-term and the repeated measurements on the same individual. To evaluate pulmonary structures and functions comprehensively in diseased lungs is extremely important and that would be needed to measure at a nature respiratory state. In this work, we tried to detect changes of several important lung properties in a mouse model of emphysema by using HP Xe MRI and MRS under the spontaneous breathing condition. Here the septal thickness and the volume ratio of the septum to the air space as pulmonary structures and ventilation, gas-exchange, and perfusion as pulmonary functions were evaluated in the same individual.