Large Volume Production of Hyperpolarized Noble Gas for Biological Magnetic Resonance Research

获奖摘要9876741 Mitch AlbertThe本项目的目标是开发必要的仪器，以常规应用超极化129（HypX）磁共振成像（MRI）和光谱（MRS）的新技术，在体外和体内进行的生物调查。 没有足够的仪器是现成的生产多升的数量所需的这样的调查。超极化惰性气体磁共振研究可能会照亮生物结构和功能，已被证明难以为传统的MR技术。 磁共振成像通常使用来自水质子的强信号，水质子在生物体中丰富，但对比度通常很低。 此外，基于质子的技术在一些最有趣的生物环境中存在缺点，特别是肺部和神经和大脑的脂质部分。129极溶于脂质，具有中等MR可检测性的自旋1/2核，但在活生物体中可达到的浓度下几乎检测不到。 通过与光学碰撞的Rb蒸汽进行自旋交换，离体129 π的超极化可以使其可检测性提高约十万倍。 循环血液中溶解的超极化氙的长弛豫时间（与回路时间相当）表明，吸入的超极化129 Xe可用作远端组织的磁共振探针。 使用超极化的129，第一个图像的气体空间在切除小鼠肺已被获得，该技术已被扩展到图像的气体空间在活的动物。 最后，129 μ S在脂质中的溶解度可以允许对富含脂质的组织（例如脑的白色物质）的灌注进行直接成像，目前任何形式的MRI都无法获得。 该奖项资助的工作希望通过开发一种稳定的高功率二极管激光驱动的光学泵浦设备来生产超极化129 Ω，从而使HypX-MRI成为常规。 该装置的主要部件将包括（a）针对大的HypX气体产生速率而优化的光学泵送室，（B）用于向受试者施用HypX的气体输送系统，（c）用于去除Rb蒸气的低温阱，以及（d）低温存储系统。 通过建模和计算机模拟，设计新颖的泵浦单元和激光传输系统，以及监测和绘制偏振的空间分布，系统的光学泵浦研究将优化系统性能。 该仪器的模块化性质将使我们能够利用改进的光源和新的概念。

Award Abstract 9876741Mitch AlbertThe objective of this project is to develop the instrumentation necessary to routinely apply the novel technique of hyperpolarized 129Xe (HypX) magnetic resonance imaging (MRI) and spectroscopy (MRS) to biological investigations conducted in vitro and in vivo. No adequate instrumentation is readily available for producing the multi-liter quantities necessary for such investigations.Hyperpolarized noble gas magnetic resonance studies may illuminate biological structures and functions that have proved difficult for conventional MR techniques. Magnetic resonance imaging usually employs the strong signal from water protons, abundant in the organism, but the contrast is often low. Moreover, proton-based techniques have shortcomings in some of the most interesting biological environments, notable the lungs and lipid parts of nerves and the brain. 129Xe is extremely soluble in lipids and has a spin-1/2 nucleus of moderate MR delectability, but is virtually undetectable at the concentrations attainable in living organisms. Hyperpolarization of 129Xe ex vivo by spin exchange with optically bumped Rb vapor can enhance its delectability by about a hundred thousand times. The long relaxation time of dissolved hyperpolarized xenon in circulating blood, comparable to the circuit time, suggests that inbreathed, hyperpolarized 129Xe can be used as a magnetic resonance probe of distal tissues. Using hyperpolarized 129Xe, the first images of the gas space in excised mouse lungs have been obtained and the technique has been extended to images of the gas space in living animals. Eventually, the solubility of 129Xe in lipids may permit direct imaging of the perfusion of lipid rich tissues such as the white matter of brain, currently inaccessible to any form of MRI.To date, HypX-MRI experiments reported in the literature suffer from relatively small volumes and low polarizations. The work funded by this award hopes to make HypX-MRI routine by developing a stable, high-power diode-laser driven optical pumping apparatus to produce liter quantities of hyperpolarized 129Xe. The major components of this apparatus will include (a) an optical pumping chamber optimized for large HypX gas production rates, (b) a gas delivery system for administration of HypX to the subject, (c) a low temperature trap for removal of Rb vapor, and (d) a cryogenic storage system. The system performance will be optimized by systematic studies of optical pumping through modeling and computer simulations, design of novel pumping cells and laser delivery systems, and monitoring and mapping the spatial distribution of the polarization. The modular nature of the instrument will allow us to utilize improved light sources and new concepts.