Near-unity nuclear polarization with an open-source 129Xe hyperpolarizer for NMR and MRI

The exquisite NMR spectral sensitivity and negligible reactivity of hyperpolarized xenon-129 ((HPXe)-Xe-129) make it attractive for a number of magnetic resonance applications; moreover, (HPXe)-Xe-129 embodies an alternative to rare and nonrenewable He-3. However, the ability to reliably and inexpensively produce large quantities of (HPXe)-Xe-129 with sufficiently high Xe-129 nuclear spin polarization (P-Xe) remains a significant challenge-particularly at high Xe densities. We present results from our open-source large-scale (similar to 1 L/h) Xe-129 polarizer for clinical, preclinical, and materials NMR and MRI research. Automated and composed mostly of off-the-shelf components, this hyperpolarizer is designed to be readily implementable in other laboratories. The device runs with high resonant photon flux (up to 200 W at the Rb D-1 line) in the xenon-rich regime (up to 1,800 torr Xe in 500 cc) in either single-batch or stopped-flow mode, negating in part the usual requirement of Xe cryocollection. Excellent agreement is observed among four independent methods used to measure spin polarization. In-cell P-Xe values of similar to 90%, similar to 57%, similar to 50%, and similar to 30% have been measured for Xe loadings of similar to 300, similar to 500, similar to 760, and similar to 1,570 torr, respectively. P-Xe values of similar to 41% and similar to 28% (with similar to 760 and similar to 1,545 torr Xe loadings) have been measured after transfer to Tedlar bags and transport to a clinical 3 T scanner for MR imaging, including demonstration of lung MRI with a healthy human subject. Long in-bag Xe-129 polarization decay times have been measured (T-1 similar to 38 min and similar to 5.9 h at similar to 1.5 mT and 3 T, respectively)-more than sufficient for a variety of applications.