부산대학교 도서관

The exquisite NMR spectral sensitivity and negligible reactivity of hyperpolarized xenon-129 (HP[sup.129]Xe) make it attractive for a number of magnetic resonance applications; moreover, HP[sup.129]Xe embodies an alternative to rare and nonrenewable [sup.3]He. However, the ability to reliably and inexpensively produce large quantities of HP[sup.129]Xe with sufficiently high [sup.129]Xe nuclear spin polarization (Pxe) remains a significant challenge--particularly at high Xe densities. We present results from our "open-source" large-scale (~1 L/h) [sup.129]Xe 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.sub.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.sub.Xe] values of ~90%, ~57%, ~50%, and ~30% have been measured for Xe loadings of ~300, ~500, ~760, and ~1,570 torr, respectively. [P.sub.Xe] values of ~41% and ~28% (with ~760 and ~1,545 torr Xe Ioadings) 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" [sup.129]Xe polarization decay times have been measured ([T.sub.1] ~38 min and ~5.9 h at ~1.5 mT and 3 T, respectively)--more than sufficient for a variety of applications. hyperpolarization | laser-polarized xenon | lung imaging | optical pumping www.pnas.org/cgi/doi/10.1073/pnas.1306586110