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

• Published in: Proceedings of the National Academy of Sciences - PNAS 2013-08, Vol.110 (35), p.14150-14155
• Main Authors: Nikolaou, Panayiotis, Coffey, Aaron M., Walkup, Laura L., Gust, Brogan M., Whiting, Nicholas, Newton, Hayley, Barcus, Scott, Muradyan, Iga, Dabaghyan, Mikayel, Moroz, Gregory D., Rosen, Matthew S., Patz, Samuel, Barlow, Michael J., Chekmenev, Eduard Y., Goodson, Boyd M.
• Format: Article
• Language: English
• Subjects: Gas spectroscopy; Humans; Imaging; Lasers; Lung - pathology; Lungs; Magnetic fields; Magnetic Resonance Imaging - methods; Magnetic Resonance Spectroscopy - methods; Nuclear magnetic resonance; Optical pumping; Physical Sciences; Polarized light; Research universities; Xenon; Xenon Isotopes - chemistry
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1306586110

The exquisite NMR spectral sensitivity and negligible reactivity of hyperpolarized xenon-129 (HP ¹²⁹Xe) make it attractive for a number of magnetic resonance applications; moreover, HP ¹²⁹Xe embodies an alternative to rare and nonrenewable ³He. However, the ability to reliably and inexpensively produce large quantities of HP ¹²⁹Xe with sufficiently high ¹²⁹Xe nuclear spin polarization (P Xₑ) remains a significant challenge—particularly at high Xe densities. We present results from our “open-source” large-scale (∼1 L/h) ¹²⁹Xe 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 ∼90%, ∼57%, ∼50%, and ∼30% have been measured for Xe loadings of ∼300, ∼500, ∼760, and ∼1,570 torr, respectively. P Xₑ values of ∼41% and ∼28% (with ∼760 and ∼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” ¹²⁹Xe polarization decay times have been measured (T ₁ ∼38 min and ∼5.9 h at ∼1.5 mT and 3 T, respectively)—more than sufficient for a variety of applications.