Recycle of 129Xe for High Resolution Lung Imaging

具有核自旋极化特性的稀有气体同位素对核磁共振具有很高的探测灵敏度，是一种极具吸引力的显像剂。特别是，自旋极化的129Xe能够对肺部和呼吸道进行快速的气体空间成像，用于临床诊断和生理研究。不幸的是，129Xe的高成本限制了可以进行的高分辨率肺部成像研究的数量。我们建议开发一种回收和循环利用同位素浓缩的氙气的系统，这样高分辨率的肺部成像就可以变得普遍和廉价。这项创新是一种低温气体分离系统，可以从患者呼出的气体中提取几乎所有的氙气，并产生高度纯净和无菌的产品。然后，回收的氙气可以重新极化，用于额外的成像程序。第一阶段项目证明了低温方法的可行性。第二阶段将通过设计、建造和演示一个完整的氙气回收装置来完成这项技术的开发。测试将证明在肺部成像程序后可以从患者体内恢复的氙气量。使用动物受试者进行的肺部成像研究将最终表明，回收的氙气可以产生高分辨率的图像，而这些图像无法与使用“新鲜”氙气制作的图像区分开来。拟议的商业应用：稀有的稀有气体同位素如果能够经济地使用，将是医学成像的潜在突破。这些同位素的用途包括肺部和呼吸道的高分辨率气体空间成像，血液灌流和脑生理学的研究，以及基于气体同位素扩散的多孔介质研究。该项目开发的技术将使这些稀有同位素能够多次重复使用，从而使这些先进的应用变得实用和经济。

Noble gas isotopes that can be nuclear spin-polarized are very attractive imaging agents because of their high detection sensitivity for nuclear magnetic resonance. In particular, spin-polarized 129Xe enables fast, gas-space imaging of the lungs and airways for clinical diagnosis and physiological studies. Unfortunately, the high cost of 129Xe limits the number of high-resolution lung-imaging studies that can be performed. We propose to develop a system to recover and recycle isotopically enriched xenon gas so that high-resolution lung imaging can become common and inexpensive. The innovation is a cryogenic gas separation system that extracts nearly all the xenon from a patient's exhaled breath and produces a highly pure and sterile product. The recovered xenon can then be repolarized and used for additional imaging procedures. The Phase I project demonstrated the feasibility of the cryogenic approach. Phase II will complete the development of this technology through design, construction, and demonstration of a complete xenon recycling device. Tests will demonstrate the amount of xenon that can be recovered from patients after a lung-imaging procedure. Lung- imaging studies using animal subjects will show conclusively that recycled xenon can produce high-resolution images that cannot be distinguished from images made using "fresh" xenon. PROPOSED COMMERCIAL APPLICATIONS: Rare, noble gas isotopes are a potential breakthrough for medical imaging if they could be used economically. Uses for these isotopes include high-resolution, gas-space imaging of the lungs and airways, studies of blood perfusion and brain physiology, and porous media studies based on diffusion of gaseous isotopes. Technology developed in this program will make these advanced applications practical and economical by enabling these rare isotopes to be reused many times.