Bio-Effects of Ultra-High MRI Gradient Slew Rates

描述（由申请人提供）：该STTR项目的动机是通过减少扫描时间和提高空间分辨率来改善MRI技术的应用。我们打算通过利用神经生理学漏洞来实现这一点：由于梯度场的生物效应的阈值可以通过显着缩短磁场上升时间来显着提高。在第一阶段，我们使用新型脉冲功率技术构建了一个超快梯度驱动器和线圈装置。这些方法使我们能够在几种无脊椎动物模型中测试生物效应，使用比典型临床系统高20万倍的磁转换速率。在第二阶段，我们将以更高的转换率跟进这些初始实验，以便在4.7特斯拉MRI中进行临床前心脏研究。这些动物心脏研究将测量比吸收率，建立纤颤阈值，评估图像质量，并检测在超高转换率下可能发生的任何组织学变化。对于后续的人类志愿者实验，我们将设定暴露的最大转换速率，其水平显著低于诱导动物心脏纤颤的最低阈值。在这项人类受试者初步研究中，我们将调整我们的超快梯度系统，以适应3T MRI系统，以确定不适的阈值，并评估MR颈动脉造影的图像质量。我们的临床进展将为该技术在市场上的传播奠定基础，而我们的技术努力将为高分辨率快速III期新生儿心脏研究做好准备。在临床上，我们的努力将与领先的儿科研究中心（儿童国家医学中心）和全国杰出的历史黑人大学（霍华德大学）协调，以提供与儿科人群特别相关的产品，这是NIH公认的服务不足的部分。这项研究的监管和科学方面预计将是开创性的，揭示从未实验研究过的梯度制度的生物效应数据。一旦这些发现得到验证，所有MRI系统制造商和用户都可能会对它们产生极大的兴趣。MRI扫描广泛用于检查血管。许多研究小组正试图用核磁共振成像研究心脏。影响MRI图像质量的一个重要因素是磁场变化的速度。不幸的是，由于副作用，高速受到限制。我们已经在动物身上证明，副作用可以通过某些技术消除。我们将在人类中研究这种现象。

DESCRIPTION (provided by applicant): The motivation for this STTR project is to improve the application of MRI technology by reducing scan times and improving spatial resolution. We intend to accomplish this by taking advantage of a neurophysiological loophole: the threshold for bio-effects due to gradient fields can be significantly raised by dramatically shortening magnetic field rise-times. In Phase I, we constructed an ultra-fast gradient driver and coil apparatus using novel pulsed-power techniques. These methods allowed us to test bio-effects in several invertebrate models, using magnetic slew rates that were 200,000 times higher than those used in typical clinical systems. In Phase II we will follow up these initial experiments with even higher slew rates, in order to conduct pre- clinical heart studies in a 4.7 Tesla MRI. These animal heart studies will measure specific absorption rate, establish thresholds for fibrillation, assess image quality, and detect any histological changes that might occur at ultra-high slew rates. For subsequent human volunteer experiments, we will set a maximum slew rate for exposure at a level significantly below the lowest threshold found to induce fibrillation in the animal hearts. In this human subject pilot study, we will adapt our ultra-fast gradient system to fit in a 3T MRI system, to determine the threshold for discomfort, and to assess image quality in MR carotid arteriograms. Our clinical progress will set the stage for dissemination of the technology into the marketplace, while our technical efforts will prepare for high-resolution fast Phase III neonatal cardiac studies. Clinically, our effort will be coordinated with a leading pediatric research center (Children's National Medical Center) and the nation's pre-eminent Historically Black University (Howard University) to deliver a product of particular relevance to the pediatric population, a segment recognized as under-served by the NIH. The regulatory and scientific aspects of this study are expected to be ground-breaking, revealing bio-effect data about gradient regimes never studied experimentally. These findings will likely be of great interest to all MRI system manufacturers and users once they are validated. PUBLIC HEALTH RELEVANCE MRI scans are widely used to examine blood vessels. Many groups are trying to study the heart with MRI. An important factor in the quality of MRI images is the speed at which magnetic fields can be changed. Unfortunately, high speeds are limited because of side-effects. We have shown in animals that side effects can be eliminated with certain techniques. We will study this phenomenon in humans.