ENHANCED PHSYIOLOGICAL MRI USING HYPERPOLARIZED 129XE

使用超极化 129XE 增强生理 MRI

• 批准号: 2901279
• 负责人: MITCHELL S ALBERT
• 金额: $ 12.05万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-04-01 至 2002-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2901279
• 关键词: biomedical equipment development; clinical research; contrast media; diagnosis design /evaluation; human subject; laboratory rat; magnetic resonance imaging; molecular energy level; respiratory function; respiratory imaging /visualization; xenon

DESCRIPTION (Adapted from Applicant's Abstract): The spin-1/2 nuclei of 3He and 129Xe 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 such hyperpolarized species makes them intriguing MR probes. The file has developed considerably in the past three years, since the applicants invented hyperpolarized-Xe MRI (HypX-MRI) by acquiring MR images of an excised mouse lung that had been inflated with hyperpolarized 129Xe. Improved lung gas space imaging has been demonstrated by others, using the stronger signal from hyperpolarized 3He, but 129Xe is the more interesting nucleus, since its high lipid solubility renders it a promising probe of organs and tissues that have yet resisted MRI techniques. Successful hyperpolarized 129Xe MR spectroscopy and MR imaging of tissues, distal to the lung, crucially depends on whether the T1 of the species in blood is long enough for sufficient magnetization to reach the target tissue. Building on our measurement of a sufficiently long T1 (13.5 sec) in oxygenated blood, to encourage HypX-MRI studies of distal tissues, the applicants proposed to undertake a series of hyperpolarized noble gas magnetic resonance experiments. The aim is to demonstrate the usefulness of the new technique in studying physiological states in animals and humans, and to further its special promise as a clinically important modality. The applicants proposed to develop a high-power, diode laser-driven, optical pumping apparatus to produce sufficient quantities of hyperpolarized 3He and 129Xe to facilitate a variety of biomedical studies. It incorporates a cryogenic storage and delivery system. Pulse sequences of HypX-MRI will be optimized in order to take advantage of the large, non-equilibrium polarization, and to exploit the large chemical shifts observed for 129Xe. RF coils for simultaneous 129Xe and 1H image acquisition will be constructed. Relaxation times (T1 and T2) of 129Xe in blood and tissue samples in vitro will be further studies as a guide to optimizing the imaging pulse sequences. Imaging of ventilated animals will attempt to evaluate usefulness of this technique to studying lung structure and function, and chemical shift imaging techniques will be used to image the brain. The possibility of using HypX-MRI to detect changes in blood flow will be explored, in the hope that it may be a first step towards imaging functional activation of the brain. Finally, experiments will test the feasibility of using this novel methodology to the study of morphology, function, and disease states in human with the goal of developing HypX-MRI for clinical diagnosis.

描述（改编自申请人的摘要）：3 He的自旋1/2核 和129 π能被超极化到它们热平衡的10^5倍 值，通过与Rb原子的自旋交换碰撞， 被圆偏振光完全“泵浦”到一个电子自旋状态。 来自这种超极化物种的增强信号使它们变得有趣 MR探头。 在过去的三年里，这个档案有了很大的发展， 由于申请人发明了超极化MRI（HypX-MRI）， 一个切除的小鼠肺的MR图像， 超极化129 Ω。 改进的肺部气体空间成像已被证明 其他人，使用超极化3 He的更强信号，但129 He是 更有趣的核，因为它的高脂溶性使它成为一个 这是一种很有前途的器官和组织的探测器，它还没有抵抗MRI技术。 组织的成功超极化129磁共振波谱和磁共振成像， 肺的远端，关键取决于物种的T1是否在 血液足够长以使足够的磁化到达目标 组织. 基于我们对足够长的T1（13.5秒）的测量， 氧合血，鼓励HypX-MRI研究远端组织， 申请人建议进行一系列超极化惰性气体 磁共振实验 其目的是证明 研究动物和人类生理状态的新技术， 并进一步促进其作为临床重要模式的特殊承诺。 的 申请人提出开发一种高功率、二极管激光驱动的光学 泵送装置，以产生足够量的超极化3 He， 129.为了促进各种生物医学研究。 它采用了 低温储存和输送系统。 HypX-MRI的脉冲序列将 优化，以利用大，非平衡 极化，并利用129 Ω观察到的大化学位移。 用于同时采集129 kHz和1H图像的RF线圈将 构建了 血液和组织中129的弛豫时间（T1和T2） 体外样品将作为指导进一步研究，以优化 成像脉冲序列。 通气动物的成像将试图 评估该技术对研究肺结构的有用性， 功能，化学位移成像技术将用于成像 个脑袋 使用HypX-MRI检测血流变化的可能性 将进行探索，希望这可能是成像的第一步， 大脑的功能激活。 最后，实验将测试 将这种新方法用于形态学研究的可行性， 功能和疾病状态，目标是开发HypX-MRI 用于临床诊断。