HYPERPOLARIZED 129XE MRI OF BRAIN FUNCTION AND PATHOLOGY

129Xe的自旋+核可以超极化到105倍 它们的热平衡值，通过与Rb的自旋交换碰撞 被圆偏振光“光学泵浦”的原子 完全进入一个电子自旋状态。增强的信号来自 超极化的129Xe使其成为一个耐人寻味的磁共振探测器。田野 在过去的三年里有了很大的发展，因为PI和 合作者发明了超极化Xe-MRI(HypX-MRI) 获取已充气的小鼠肺的磁共振图像 超极化的129Xe。改进的肺空间成像已经被 其他人演示了，使用来自超极化的更强的信号 3He，但129Xe是更有趣的核，因为它的高脂 它的溶解性使其成为器官和组织的一种有前途的探针。我们 建议将HypX-MRI新技术发展为研究 和用于研究大脑状态的诊断工具，具有 阐明脑功能和病理的具体意图。 氙气的亲脂性，对环境的高度敏感性，以及它的 超极化后的高可检测性，允许设计 实验方法与使用的方法完全不同 常规核磁共振检查。吸入的129Xe迅速扩散到肺内 血液通过循环被分配到远端组织。成功 脑部的超极化129Xe磁共振成像和光谱分析 取决于血液中129Xe的T1是否足够长 足够的磁化强度到达目标组织。我们的尺寸 氧合血液中足够长的T1(13.5秒)会鼓励 脑组织的HypX-MRI研究。我们建议发展HYPX- 将MRI转变为一种敏感、非侵入性和定量的方法 通过测量局部区域来绘制大脑的功能活动图 脑血流量(RCBF)，并通过129Xe的敏感性 MR参数对环境的影响。氙气在水溶液中的微分溶解度 大脑的白质和灰质，以及它的大量化学物质 不同环境中的换班和放松时间，也表明 HypX-MRI可用于描述各种脑部病变。 在构建了基于激光的光学泵浦系统后，常规 积累大量超极化的129Xe，它将是 与存储和传送系统接口。特殊脉冲序列 将被开发为最好地利用大型但不可再生的 超极化贵金属的一个特殊特征--磁化 气磁共振研究。HypeX磁共振研究，活体，使用动物 应该允许对使用这种新技术的可行性进行评估 研究rCFB和脑功能，以及各种神经学和 精神性大脑障碍，在人类身上。

The spin- + nuclei of 129 Xe can be "hyperpolarized" to 10 5 times their thermal equilibrium value, by spin-exchange collisions with Rb atoms that have been "optically pumped" by circularly polarized light entirely into one electron spin state. The enhanced signal from hyperpolarized 129 Xe makes it an intriguing MR probe. The field has developed considerably in the past three years, since the PI and collaborators invented hyperpolarized Xe-MRI (HypX-MRI) by acquiring MR images of excised mouse lungs that had been inflated with hyperpolarized 129 Xe. Improved lung space imaging has been demonstrated by others, using the stronger signal from hyperpolarized 3He, but 129 Xe is the more interesting nucleus, since its high lipid solubility renders it a promising probe of organs and tissues. We propose to develop the novel technology of HypX-MRI into a research and diagnostic tool for the study of the states of the brain, with the specific intention of elucidating brain function and pathology. Xenon's lipophilicity, its high sensitivity to its environment, and its high detectable after hyperpolarization, allow for the design of experimental approaches radically different from those used in conventional MRI. Inhaled 129Xe rapidly diffuses into the pulmonary blood and is distributed to distal tissues by the circulation. Successful hyperpolarized 129 Xe MRI and spectroscopy of the brain crucially depends on whether the T 1 of 129 Xe in blood is long enough for sufficient magnetization to reach the target tissue. Our measurement of a sufficiently long T 1 (13.5 sec) in oxygenated blood encourages HypX-MRI studies of brain tissue. We propose to develop HYPX- MRI into a sensitive, non-invasive, and quantitative method for mapping functional activity of the brain, through measuring regional cerebral blood flow (rCBF), and through the sensitivity of 129 Xe's MR parameters to the environment. Xenon's differential solubility in the white and gray matter of the brain, and its large range of chemical shift and relaxation times in different environments, also suggests that HypX-MRI may be useful in delineation of various brain pathologies. After constructing a laser-based optical-pumping system to routinely accumulate liter-large quantities of hyperpolarized 129 Xe, it will be interfaced with a storage and delivery system. Special pulse sequences will be developed to best utilize the large, but non-renewable, magnetization which is a special feature of hyperpolarized noble gasMR studies. HypeX MR investigations, in vivo, using animals should permit evaluation of the feasibility of using this novel technique to study rCFB and brain function, and a variety of neurological and psychiatric brain disorders, in humans.