XeNA: An automated 'open-source' super(129)Xe hyperpolarizer for clinical use

• Published in: Magnetic resonance imaging Vol. 32; no. 5; pp. 541 - 550
• Main Authors: Nikolaou, Panayiotis, Coffey, Aaron M, Walkup, Laura L, Gust, Brogan M, Whiting, Nicholas, Newton, Hayley, Muradyan, Iga, Dabaghyan, Mikayel, Ranta, Kaili, Moroz, Gregory D, Rosen, Matthew S, Patz, Samuel, Barlow, Michael J, Chekmenev, Eduard Y, Goodson, Boyd M
• Format: Journal Article
• Language: English
• Published: 01-06-2014
• ISSN: 0730-725X
• DOI: 10.1016/j.mri.2014.02.002

Here we provide a full report on the construction, components, and capabilities of our consortium's "open-source" large-scale (~ 1 L/h) super(129)Xe hyperpolarizer for clinical, pre-clinical, and materials NMR/MRI (Nikolaou et al., Proc. Natl. Acad. Sci. USA, 110, 14150 (2013)). The 'hyperpolarizer' is automated and built mostly of off-the-shelf components; moreover, it is designed to be cost-effective and installed in both research laboratories and clinical settings with materials costing less than $125,000. The device runs in the xenon-rich regime (up to 1800 Torr Xe in 0.5 L) in either stopped-flow or single-batch mode-making cryo-collection of the hyperpolarized gas unnecessary for many applications. In-cell super(129)Xe nuclear spin polarization values of ~ 30%-90% have been measured for Xe loadings of ~ 300-1600 Torr. Typical super(129)Xe polarization build-up and T sub(1) relaxation time constants were ~ 8.5 min and ~ 1.9 h respectively under our spin-exchange optical pumping conditions; such ratios, combined with near-unity Rb electron spin polarizations enabled by the high resonant laser power (up to ~ 200 W), permit such high P sub(Xe) values to be achieved despite the high in-cell Xe densities. Importantly, most of the polarization is maintained during efficient HP gas transfer to other containers, and ultra-long super(129)Xe relaxation times (up to nearly 6 h) were observed in Tedlar bags following transport to a clinical 3 T scanner for MR spectroscopy and imaging as a prelude to in vivo experiments. The device has received FDA IND approval for a clinical study of chronic obstructive pulmonary disease subjects. The primary focus of this paper is on the technical/engineering development of the polarizer, with the explicit goals of facilitating the adaptation of design features and operative modes into other laboratories, and of spurring the further advancement of HP-gas MR applications in biomedicine.