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.

项目概要 在这个项目中，我们提出了一种基于我们创新的快速磁共振成像（MRI）的新概念 开关磁场磁铁设计。我们相信这种 MRI 磁体将使新的对比机制成为可能 以及用于生物医学研究的比率分子成像。我们将开发并演示液氦 不含 LHe 的超导磁体，可以在显着不同的时间之间快速改变磁场 场强：足以进行弛豫测量和预极化的中等均匀性的高 (3T) 场；和一个低 (0.5T) 光谱和成像的高均匀性场。由此启用的新对比机制 磁体包括自旋 1/2 和四极核之间的能级交叉、加速自旋晶格弛豫以及 绝热退磁-再磁化。通过测量不同场的弛豫参数，弛豫 可以区分在场上具有不同相对弛豫率的对比源。这会有所帮助 根据背景量化显像剂浓度或区分表现出的各个试剂的状态 放松行为的环境依赖性变化。超导磁体中的快速磁场变化 可以通过采用最先进的低交流损耗高温超导体（HTS）来实现 足够高的温度裕度以避免淬火。两个场之间的场切换时间会很快 足够（<1秒）来保留偏振和弛豫测量，但对动物和人类来说是安全的。我们的其他应用 开关场磁体可能包括介入磁共振和术中手术。 0.5 T 磁化率伪影 来自微磁性设备和植入物的热量，以及来自传导设备的射频热量要少得多。我们相信 通过不断进步的 MR 光谱和成像技术，图像可与 1.5 T 相当。我们是 相信我们提出的切换场磁流变磁体不仅可以带来新颖的对比机制，而且可以 也可以作为临床前动物甚至人类 MRI 的垫脚石，具有竞争力和成本效益 传统 MRI 磁体。具体目标是开发一种无 LHe 快速切换场 MRI 磁体 通过组合两个 HTS 磁体（一个 2.5-T 开关场磁体和一个 0.5-T MRI 磁体）来制作原型 展示快速场切换（高达 3 T/s）期间的 MRI 场均匀性和稳定性。我们还将表演 具有最佳设计场的人体尺寸快速切换场 MRI 磁体的概念设计。独特的 我们的磁铁设计的特点是在快速开关场中损耗非常低且稳定，这是不可能的 传统的低温超导体（LTS），以及两个单独运行的高温超导体的配置 磁铁——高均匀性的稳定低磁场和中等磁场质量的快速循环高磁场——以实现 快速切换功能在性能和成本方面高效。我们的固氮冷却低温系统不 依赖氦气，而氦气已成为一种稀缺且不可靠的商品。该项目的顺利完成将 为更大（包括人类规模）和更高磁场的磁铁铺平道路，从而有利于生物医学科学。