Free-Breathing Hyperpolarized Xenon-129 Spectroscopy with Cardiopulmonary Gating

While hyperpolarized 129Xe (HXe) MRI is capable of quantifying gas exchange, these measurements are heavily dependent on both cardiac and pulmonary activity. Since traditional HXe approaches are performed during extended breath-holds at fixed lung inflation levels, the measured gas exchange can differ greatly based on the chosen inflation position, and may thus not be representative of steady-state behavior. To explore the sensitivity of HXe to cardiac pulsations and the different phases of respiration, we acquired spectra continuously over approximately 40 breaths of low-dose HXe before retrospectively gating the signals based on both cardiac and respiratory cycles.