Pathway to cryogen free production of hyperpolarized krypton-83 and xenon-129

Six, Joseph S., Hughes-Riley, Theodore, Stupic, Karl F., Pavlovskaya, Galina E. and Meersmann, Thomas (2012) Pathway to cryogen free production of hyperpolarized krypton-83 and xenon-129. PLoS ONE, 7 (11). e49927/1-e49927/16. ISSN 1932-6203

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yperpolarized (hp) 129Xe and hp 83Kr for magnetic resonance imaging (MRI) are typically obtained through spin-exchange

optical pumping (SEOP) in gas mixtures with dilute concentrations of the respective noble gas. The usage of dilute noble gases mixtures requires cryogenic gas separation after SEOP, a step that makes clinical and preclinical applications of hp 129Xe MRI cumbersome. For hp 83Kr MRI, cryogenic concentration is not practical due to depolarization that is caused by quadrupolar relaxation in the condensed phase. In this work, the concept of stopped flow SEOP with concentrated noble gas mixtures at low pressures was explored using a laser with 23.3 W of output power and 0.25 nm linewidth. For 129Xe SEOP without cryogenic separation, the highest obtained MR signal intensity from the hp xenon-nitrogen gas mixture was

equivalent to that arising from 15.561.9% spin polarized 129Xe in pure xenon gas. The production rate of the hp gas

mixture, measured at 298 K, was 1.8 cm3/min. For hp 83Kr, the equivalent of 4.460.5% spin polarization in pure krypton at a production rate of 2 cm3/min was produced. The general dependency of spin polarization upon gas pressure obtained in stopped flow SEOP is reported for various noble gas concentrations. Aspects of SEOP specific to the two noble gas isotopes are discussed and compared with current theoretical opinions. A non-linear pressure broadening of the Rb D1 transition was observed and taken into account for the qualitative description of the SEOP process.

Item Type: Article
Schools/Departments: University of Nottingham, UK > Faculty of Medicine and Health Sciences > School of Medicine > Medical Education Unit and Medical Courses Office
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Depositing User: de Sousa, Mrs Shona
Date Deposited: 04 Apr 2014 13:44
Last Modified: 04 May 2020 16:34

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