Free-Breathing Dynamic Cardiopulmonary Function Imaging System to use with Xenon MRI

ABSTRACT This project seeks to build, qualify and evaluate clinical feasibility of a novel cardiopulmonary imaging device for continuous administration of the gaseous Magnetic Resonance Imaging contrast agent Hyperpolarized Xenon-129 (HPX), recently approved by the FDA. Paired with a clinically practical set of physiological monitoring measurements, we intend this development to support a new paradigm for functional lung imaging that is accessible to all patients regardless of age or disease state, removes sources of irreproducibility and bias associated with images acquired during extended breath-hold, and offers new opportunities for contrast associated with the dynamic aspects of gas- and blood-flow in an organ that during normal functioning is always in motion. We pursue this goal by first designing and building an automatic, MRI-compatible, piston-based set of syringe pumps that respond to subject breathing dynamics by injecting supplemental HPX or oxygen (or any other desired agent) into the inhaled gas stream. Based on an existing product used for HPX in ventilated small-animal studies, this device will accumulate and respond to passively-obtained pneumotach measures of airflow, allowing bolus or constant- concentration delivery as desired, as well as synchronization with the MR imaging data, the heartbeat, and exhaled gas concentrations, without the need for patient compliance with breathing maneuvers. The combined dataset will support identification of abnormal ventilation, perfusion or gas diffusion during physiologically relevant conditions. Subsequently synchronous monitoring and capturing of inhaled and exhaled O2, CO2 and xenon concentrations is incorporated throughout the breathing cycle. This project also aims to demonstrate feasibility of the dynamic lung HPX MRI in a small pilot study. Identifying key design issues, evaluating patient tolerance and collecting preliminary feedback from clinical support staff are essential at this design stage in order to inform key device validation activities in Phase II including device validation and human factors.