HYPERPOLARIZED 129XE MRI OF BRAIN FUNCTION AND PATHOLOGY

自旋为129的自旋+核可以被“超极化”到105倍 通过与Rb的自旋交换碰撞， 被圆偏振光“光泵浦”的原子 完全变成一个电子自旋状态 增强信号来自 超极化129 Ω使其成为一种有趣的MR探针。 领域 在过去的三年里，自PI和 合作者发明了超极化Xe-MRI（HypX-MRI）， 获取切除的小鼠肺的MR图像， 超极化129欧姆。 改进的肺空间成像已经被 由其他人证明，使用超极化的更强信号， 3 He，但129 He是更有趣的核，因为它的高脂 溶解性使其成为器官和组织的有希望的探针。 我们 建议将HypX-MRI的新技术发展为研究 和诊断工具，用于研究大脑的状态， 阐明脑功能和病理学的具体意图。 氙的亲油性、对环境的高敏感性及其 在超极化后高度可检测，允许设计 实验方法完全不同于 常规MRI。 吸入的129氚迅速扩散到肺部 血液并通过循环分布到远端组织。 成功 超极化129磁共振成像和光谱的大脑至关重要 取决于血液中129伏的T1是否足够长， 足够的磁化以到达目标组织。 我们的测量 氧合血中足够长的T1（13.5秒） 脑组织的HypX-MRI研究。 我们建议开发HYPX- MRI成为一种灵敏、非侵入性和定量的方法， 绘制大脑的功能活动，通过测量区域 脑血流量（rCBF），并通过129 μ s的灵敏度 MR参数与环境的关系。 氙的溶解度差 大脑的白色和灰质，以及其大量的化学物质， 在不同环境中的位移和弛豫时间，也表明， HypX-MRI可用于描绘各种脑部病变。 在构建了基于激光的光泵浦系统之后， 积累升-大量的超极化129欧姆，它将是 与一个储存和运输系统连接。 特殊脉冲序列 将被开发，以最好地利用大，但不可再生， 磁化强度，这是一个特殊的特点，超极化贵金属 gasMR研究。HypeX MR研究，体内，使用动物 应该允许评估使用这种新技术的可行性 研究rCFB和脑功能，以及各种神经和 人类的精神性大脑紊乱

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.