High-Performance Gradient Coil for 7 Tesla MRI

项目总结/摘要 该应用旨在升级Athinoula A现有的7特斯拉人体MRI扫描仪。马蒂诺斯中心 用于生物医学成像拟议的升级包括新推出的高性能股骨头梯度 最大回转速率700 T/m/s，强度200 mT/m， 是目前常规使用的最先进梯度线圈的两倍。这种创新的梯度线圈，“脉冲”， 由西门子专门为7 T设计，并由Martinos调查人员提供意见，并克服了 上一代梯度线圈的性能限制。它目前仅在一个7 T站点（UC Berkeley）使用。 该梯度线圈的附加性能提供的关键优势是更快的大脑图像编码 显像这可以用于在许多技术中改善图像质量，特别是回波平面成像 (EPI)这是功能成像研究以及扩散和灌注MR的主力方法 显像更高的性能将有助于减少失真和模糊等伪影，这些伪影存在于 EPI在这些更高的磁场强度，从而提高数据质量的广泛范围内， 应用.更快的成像速度还可以为高分辨率功能提供必要的编码 MRI（fMRI）在T2* 信号衰减提供的有限时间窗内。虽然7 T提供了大量的 fMRI灵敏度的提高，越来越多的证据表明，fMRI的内在生物分辨率是很好的， 在毫米级以下，现有的硬件平台不能实现许多人所期望的成像分辨率。 因此，今天，7 T fMRI被称为“编码限制”。这种梯度线圈将有助于超越这些 编码限制，以帮助获得7 T功能磁共振成像的全部潜力。高梯度强度结合高强度 该梯度线圈的转换速率也将有助于通过减少扩散编码 持续时间和图像编码时间，这通常受到超高场下快速T2衰减的挑战。高 转换速率也将提高先进的解剖成像方法的性能，如我们的“波CAIPI”方法 这可以实现更高的加速因子和更快的转换速率，用于高分辨率解剖成像。 Martinos中心在类似的上一代头部梯度线圈方面拥有丰富的经验。我们有 优化这种强大的新型梯度线圈性能的技术专长，以及一个工程师团队， 支持仪器并开发和发明新的应用程序。总体而言，这一拟议的升级将有利于 Martinos中心的广泛用户群和波士顿地区的许多附属研究人员， 使用我们的设施，为研究者提供创新临床，转化， 和基础研究。这项令人兴奋的技术将使新的实验成为可能，从而可能产生新的 资金支持，并吸引有才华的开发人员和新的调查人员。最后，这个项目的成功 仪器升级将有助于为其他公共卫生系统资助的研究中心采用这一下一个- 新一代梯度线圈，并帮助推出一个社区的研究人员使用这一变革性的新技术。

PROJECT SUMMARY/ABSTRACT This application seeks to upgrade an existing 7 Tesla human MRI scanner at the Athinoula A. Martinos Center for Biomedical Imaging. The proposed upgrade consists of newly available high-performance head gradient coil, the most powerful of its kind—with maximum slewrate of 700 T/m/s and strength of 200 mT/m, more than twice that of the most advanced gradient coils in regular use today. This innovative gradient coil, the "Impulse", was designed exclusively for 7T by Siemens with input from Martinos investigators, and has overcome the performance limits of previous-generation gradient coils. It is currently in use only at one 7T site (UC Berkeley). The key advantage provided by this gradient coil’s added performance is faster image encoding for brain imaging. This can be utilized to improve image quality in many techniques, in particular echo planar imaging (EPI), which is the workhorse method for functional imaging studies as well as diffusion, and perfusion MR imaging. The higher performance will help reduce artifacts such as distortion and blurring, which are present in EPI at these higher magnetic field strengths, and thereby enhance data quality for a broad range of applications. The faster imaging speeds can also provide the necessary encoding for high-resolution functional MRI (fMRI) within the limited time-window afforded by T2* signal decay. Although 7T provides a substantial boost in fMRI sensitivity, and mounting evidence indicates that the intrinsic biological resolution of fMRI is well below the millimeter scale, existing hardware platforms cannot achieve the imaging resolution desired for many experiments—thus today, 7T fMRI is known to be “encoding limited”. This gradient coil will help surpass these encoding limits to help reap the full potential of 7T fMRI. The high gradient strength combined with the high slew rate of this gradient coil will also help enable diffusion MRI at 7T by reducing both the diffusion encoding duration and image encoding times, which is typically challenged by rapid T2 decay at ultra-high field. The high slew rate will also boost performance of advanced anatomical imaging methods like our “wave-CAIPI” method that can achieve even higher acceleration factors with faster slew rates for high-resolution anatomical imaging. The Martinos Center has vast experience with similar previous-generation head gradient coils. We have the technical expertise to optimize performance of this powerful new gradient coil, and a team of engineers to support the instrument and develop—and invent—new applications. Overall, this proposed upgrade will benefit the broad user base within the Martinos Center and the many affiliated researchers within the Boston area who use our facilities, providing investigators with a technological edge required for innovative clinical, translational, and basic research. This exciting technology will enable new experiments and thus will likely generate new funding support, and attract talented developers and new investigators. Finally, the success of this instrumentation upgrade will help pave the way for other PHS-funded research centers to adopt this next- generation gradient coil and help launch a community of researchers using this transformative new technology.