Effect of reduced pressure on the polarization of ¹²⁹Xe in the production of hyperpolarized ¹²⁹Xe gas: Development of a simple continuous flow mode hyperpolarizing system working at pressures as low as 0.15 atm

Abstract

Abstract The effect of reduced pressure on the polarization of 129 Xe has been examined in batch and continuous flow modes aiming at developing a simple and convenient hyperpolarizing system. The effect of foreign gases was found to show a different tendency at reduced pressure as low as 0.15 atm compared to that near atmospheric pressure. For example, 129 Xe polarization in binary mixtures of Xe and N 2 was larger than that observed in ternary mixtures of Xe, N 2 , and 4 He when compared with the same Xe content, and the highest polarization of 63.6% was given by the 5% Xe + 95% N 2 mixture in the batch mode. The most noticeable result in the flow mode was that 129 Xe polarization reached a plateau at 0.15 atm when cell pressure was reduced from atmospheric pressure, being enhanced to about twice of that observed near atmospheric pressure. Also demonstrated is the use of isotopically enriched 129 Xe gas at reduced partial pressure. This will be devoid of the anesthetic side effects of Xe while making use of enhanced polarization at reduced pressure, leading to the development of a simple and convenient hyperpolarizing system for medical use. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 33B: 192–200, 2008