A Compact LHe-Free Fast-Switching-Field MRI Magnet for Ratiometric Molecular Imaging and Novel Contrast Exploration

用于比例分子成像和新颖对比探索的紧凑型无 LHe 快速切换场 MRI 磁体

• 批准号: 10433443
• 负责人: Dongkeun Park
• 金额: $ 19.95万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-15 至 2024-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10433443
• 关键词: Adopted; Animals; Behavior; Biological; Biomedical Research; Cell Nucleus; Development; Devices; Diagnosis; Electromagnetics; Environment; Exhibits; Exploratory/Developmental Grant; Filament; Generations; Goals; Heating; Helium; High temperature of physical object; Human; Image; Imaging technology; Implant; Individual; Intervention; Liquid substance; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Magnetism; Measures; Medical; Molecular; Morphologic artifacts; Motivation; Nitrogen; Operative Surgical Procedures; Performance; Predisposition; Procedures; Relaxation; Scanning; Science; Societies; Solid; Source; Spectrum Analysis; System; Technology; Temperature; Testing; Time; Tissues; animal imaging; base; biological research; cold temperature; cost; cost effective; cryogenics; design; human subject; imaging agent; imaging system; innovation; magnetic field; molecular imaging; novel; operation; pre-clinical; programs; prototype; ratiometric; scale up; spectroscopic imaging; wound

Project Summary In this project we propose a novel magnetic resonance imaging (MRI) concept based on our innovative fast- switching-field magnet design. We believe that this MRI magnet will make possible new contrast mechanisms and ratiometric molecular imaging for biomedical research. We will develop and demonstrate a liquid-helium (LHe)-free superconducting magnet that can change the field very quickly in time between significantly different field strengths: a high (3T) field of modest-homogeneity adequate for relaxometry and prepolarization; and a low (0.5T) field of high-homogeneity for spectroscopy and imaging. New contrast mechanisms enabled by this magnet include level-crossing between spin 1/2 and quadrupolar nuclei, accelerated spin-lattice relaxation, and adiabatic demagnetization-remagnetization. By measuring relaxation parameters at different fields, relaxation contrast sources that have different relative relaxation rates at the fields could be distinguished. This will help quantify imaging agent concentrations against background or differentiate states of individual agents that exhibit environmentally-dependent changes in relaxation behavior. The fast field change in a superconducting magnet can be achieved by adopting most advanced low-AC-loss high-temperature superconductors (HTS) having a sufficiently high temperature margin to avoid quench. The field switching time between two fields will be rapid enough (<1 s) to retain polarization and relaxometry yet safe for animal and human. Other applications of our switching-field magnet might include interventional MR and intraoperative surgery. At 0.5 T susceptibility artifacts from slightly magnetic devices and implants, and RF heating from conductive devices are much less. We believe the images can be comparable to 1.5 T with progressing MR spectroscopy and imaging technologies. We are convinced that our proposed switching-field MR magnet can not only promise novel contrast mechanisms but also serve as a stepping stone for preclinical animal and even human MRI competitive and cost effective against conventional MRI magnets. The specific aims are to develop a LHe-free fast-switching-field MRI magnet prototype by combining two HTS magnets—a 2.5-T switched-field magnet and a 0.5-T MRI magnet—and demonstrate the MRI field homogeneity and stability during fast field-switching (up to 3 T/s). We will also perform a conceptual design of a human-size fast-switching-field MRI magnet with optimum design fields. The unique features of our magnet design are very low-loss and stable in a fast-switching field, impossible with a conventional low-temperature superconductor (LTS), and configuration of two separately operating HTS magnets—a steady low field of high-homogeneity and a fast-cycling high field of modest-field-quality—to achieve fast-switching feature efficiently in performance and cost. Our solid-nitrogen-cooled cryogenic system does not rely on helium, which has become a scarce and unreliable commodity. Successful completion of this project will pave the way to larger—including human-scale—and higher field magnets, benefitting biomedical sciences.

项目摘要 在这个项目中，我们提出了一种基于我们创新的快速的新型磁共振成像（MRI）概念 切换场磁铁设计。我们认为，这款MRI磁铁将使新的对比机制成为可能 和比例分子成像用于生物医学研究。我们将开发并演示液晶 （LHE） - 可以在显着差异之间迅速改变场地的无超导磁铁 野外强度：适度的高（3T）田地足以用于松弛和前偏度；和低点 （0.5T）用于光谱和成像的高均匀性领域。这使得新的对比机制 磁铁包括自旋1/2和四极核之间的水平交叉，加速自旋晶格松弛，以及 绝热地消灭磁通化。通过测量不同领域的放松参数，放松 可以区分田野相对放松率不同的对比来源。这将有所帮助 量化成像剂浓度相对于背景或分化的单个药物的态度 放松行为的环境依赖性变化。超导磁铁的快速场变化 可以通过采用最先进的低速损坏高温超导体（HTS）来实现 足够高的温度余量以避免淬火。两个字段之间的场切换时间将很快 足够（<1 s）可以保留极化和松弛计，但对动物和人类安全。我们的其他应用 切换场磁铁可能包括介入手术和术中手术。在0.5吨易感性伪像 从略带磁性的设备和直接以及导电设备的RF加热较少。我们相信 图像可以与1.5 t相媲美，而MR光谱和成像技术的进展可以。我们是 确信我们提议的切换场MR磁铁不仅可以承诺新颖的对比机制，而且可以 还可以作为临床前动物甚至人类MRI竞争力和成本效益的垫脚石 常规的MRI磁铁。具体的目的是开发无LHE的快速转换场MRI磁铁 原型通过将两种HTS磁铁结合在一起（2.5-T开关场磁铁和0.5-T MRI磁铁）和 在快速野外切换期间（最多3 t/s）演示MRI场的均匀性和稳定性。我们也会表演 具有最佳设计字段的人类大小快速磁场MRI磁铁的概念设计。独特 我们的磁铁设计的功能在快速切换的领域非常低且稳定，不可能 常规的低温超导体（LTS）和两个单独操作HT的配置 磁铁 - 高均匀性的稳定低场和快速循环的高田间质量的高田 快速转换功能有效地表现和成本。我们的固体冷却低温系统不 依靠氦气，这已成为一种稀缺和不可靠的商品。成功完成该项目将 铺平了通往更大的道路（包括人类规模）和更高的田地磁铁，从而使生物医学科学受益。