Pathway to Cryogen Free Production of Hyperpolarized Krypton-83 and Xenon-129
Pathway to Cryogen Free Production of Hyperpolarized Krypton-83 and Xenon-129
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DOI：
10.1371/journal.pone.0049927
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发表时间：
2012-11-27
期刊：
影响因子：
3.7
通讯作者：
Meersmann, Thomas
中科院分区：
文献类型：
--
作者：
Six, Joseph S.;Hughes-Riley, Theodore;Meersmann, Thomas
用于磁共振成像（MRI）的超极化（hp）Kr-129和hp Kr-83通常通过在具有稀释浓度的相应惰性气体的气体混合物中的自旋交换光泵浦（SEOP）获得。使用稀释的惰性气体混合物需要在SEOP之后进行低温气体分离，这一步骤使得hp MRI-129 MRI的临床和临床前应用变得繁琐。对于hp Kr-83 MRI，由于凝聚相中四极弛豫引起的去极化，低温浓缩不实用。在这项工作中，停流SEOP的概念与浓缩的惰性气体混合物在低压下进行了探索，使用激光器与23.3 W的输出功率和0.25 nm的线宽。对于没有低温分离的Xe-129 SEOP，从hp氙气-氮气混合物获得的最高MR信号强度相当于纯氙气中15.5 +/-1.9%自旋极化的Xe-129产生的信号强度。在298 K下测量的hp气体混合物的产生速率为1.8 cm（3）/min。对于hp Kr-83，在纯氪中以2 cm（3）/min的产生速率产生了4.4 +/- 0.5%的自旋极化。自旋极化对气体压力的一般依赖性在停止流动SEOP中获得的各种惰性气体浓度的报告。方面的SEOP具体的两种惰性气体同位素进行了讨论，并与目前的理论观点。观察到Rb D-1跃迁的非线性压力增宽，并考虑到SEOP过程的定性描述。
Hyperpolarized (hp) Xe-129 and hp Kr-83 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 Xe-129 MRI cumbersome. For hp Kr-83 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 Xe-129 SEOP without cryogenic separation, the highest obtained MR signal intensity from the hp xenon-nitrogen gas mixture was equivalent to that arising from 15.5 +/- 1.9% spin polarized Xe-129 in pure xenon gas. The production rate of the hp gas mixture, measured at 298 K, was 1.8 cm(3)/min. For hp Kr-83, the equivalent of 4.4 +/- 0.5% spin polarization in pure krypton at a production rate of 2 cm(3)/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 D-1 transition was observed and taken into account for the qualitative description of the SEOP process.