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

基本信息

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
项目类别：
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

项目摘要

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）的新概念我们相信这种 MRI 磁体将使新的对比机制成为可能。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：适合弛豫测量和预极化的中等均匀度的高 (3T) 场； (0.5T) 光谱和成像的高均匀性领域由此实现。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，这将有所帮助。根据背景对定量试剂浓度进行成像，或区分表现出的各个试剂的状态超导磁体中的快速磁场变化取决于环境。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失超两个场之间的场切换时间将很快。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。切换场磁体可能包括介入 MR 和术中手术 0.5 T 磁化率伪影。我们认为，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。通过不断进步的 MR 光谱和成像技术，图像可与 1.5 T 相媲美。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常规 MRI 磁体的具体目标是开发一种无 LHe 的快速切换场 MRI 磁体。通过组合两个 HTS 磁体（一个 2.5-T 切换磁场磁体和一个 0.5-T MRI 磁体）来制作原型我们还将展示快速场切换（高达 3 T/s）期间的 MRI 场均匀性和稳定性。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。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——以实现我们的固氮冷却低温系统没有提供高效的快速切换功能。依靠氦气，氦气已成为一种稀缺且不可靠的商品，该项目的成功完成将成为可能。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。