In vivo MRI using real-time production of hyperpolarized 129Xe

MR imaging of hyperpolarized (HP) nuclei is challenging because they are typically delivered in a single dose of nonrenewable magnetization, from which the entire image must be derived. This problem can be overcome with HP Xe-129, which can be produced sufficiently rapidly to deliver in dilute form (1%) continuously and on-demand. We demonstrate a real-time in vivo delivery of HP Xe-129 mixture to rats, a capability we now routinely use for setting frequency, transmitter gain, shimming, testing pulse sequences, scout imaging, and spectroscopy. Compared to images acquired using conventional fully concentrated Xe-129, real-time Xe-129 images have 26-fold less signal, but clearly depict ventilation abnormalities. Real-time (12)9Xe MRI could be useful for time-course studies involving acute injury or response to treatment. Ultimately, real-time Xe-129 MRI could be done with more highly concentrated Xe-129, which could increase the signal-to-noise ratio by 100 relative to these results to enable a new class of gas imaging applications.