ENHANCED PHSYIOLOGICAL MRI USING HYPERPOLARIZED 129XE

描述(摘自申请者摘要)：3He的自旋1/2核 而129Xe可以超极化到其热平衡的10^5倍 价值是通过与Rb原子的自旋交换碰撞而产生的，这些Rb原子已经 被圆偏振光完全泵浦到一个电子自旋态。 来自这种超极化物种的增强信号使它们变得耐人寻味 先生探查。在过去的三年里，档案有了很大的发展， 由于申请人通过获取超极化Xe磁共振成像(HypX-MRI) 切除的小鼠肺被充气的磁共振图像 超极化的129Xe改进的肺气体空间成像已被证明 其他人使用的是来自超极化3He的更强信号，但129Xe是 更有趣的是原子核，因为它的高脂溶性使它成为 对尚未抵抗核磁共振技术的器官和组织进行有希望的探测。 成功的超极化129Xe磁共振波谱和组织的磁共振成像， 在肺的远端，关键取决于物种的T1是否在 血液足够长，足够的磁化作用到达目标 组织。基于我们对足够长的T1(13.5秒)的测量 含氧血液，为了鼓励对远端组织进行HypX-MRI研究， 申请者建议进行一系列超极化惰性气体 磁共振实验。这样做的目的是证明 研究动物和人类生理状态的新技术， 并进一步发展其作为临床重要手段的特殊前景。这个 申请人建议开发一种大功率、半导体激光驱动、光学 泵浦装置产生足够数量的超极化~3He和 129Xe，以促进各种生物医学研究。它包含了一个 低温储存和输送系统。HypX-MRI的脉冲序列将是 优化以利用大的、非平衡的 极化，并利用观察到的129Xe的大化学位移。 用于同时采集129Xe和1H图像的射频线圈将 建造的。~(129)Xe在血液和组织中的弛豫时间(T1和T2) 体外样品将进一步研究，以指导优化 成像脉冲序列。对通风动物的成像将尝试 评价该技术在研究肺结构和肺功能中的作用 功能，并将使用化学位移成像技术来成像 大脑。应用HypX-MRI检测血流变化的可能性 将被探索，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 将这种新的方法应用于形态学研究的可行性， 人类的功能和疾病状态，目标是开发HypX-MRI 用于临床诊断。

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.