Bio-Effects of Ultra-High MRI Gradient Slew Rates

超高 MRI 梯度转换率的生物效应

• 批准号: 7537842
• 负责人: STANLEY THOMAS FRICKE
• 金额: $ 69.01万
• 依托单位: WEINBERG MEDICAL PHYSICS, LLC
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-15 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7537842
• 关键词: Adopted; Adult; Adverse effects; African American; Amplifiers; Animal Model; Animals; Arteriogram; Blood Vessels; Cardiac; Child; Childhood; Clinical; Clinical Trials; Code; Communities; Compatible; Data; Development; Devices; Electric Countershock; Electromagnetics; Electronics; Elements; European; Facility Construction Funding Category; Family suidae; Generations; Goals; Guidelines; Head and neck structure; Heart; Human; Human Volunteers; IACUC; Image; Industry; International; Invertebrates; Life; Limb structure; Lithotripsy; MRI Scans; Magnetic Resonance Imaging; Magnetism; Manufacturer Name; Marketing; Measurement; Measures; Medical; Medical center; Methods; Modeling; Motivation; Nature; Neonatal; Organism; Pediatric Research; Phase; Phase II Clinical Trials; Physiologic pulse; Physiological; Pilot Projects; Population; Positioning Attribute; Preparation; Protocols documentation; Public Health; Publishing; Pulse taking; Rate; Regulation; Resolution; Safety; Scanning; Small Business Technology Transfer Research; Speed; Staging; Standards of Weights and Measures; Sus scrofa; System; Techniques; Technology; Temperature; Testing; Time; United States Food and Drug Administration; United States National Institutes of Health; Universities; Vertebrates; absorption; base; commercialization; cost effective; design; follow-up; human study; human subject; improved; innovation; interest; magnetic field; neurophysiology; novel; pre-clinical; research study; satisfaction; solid state; volunteer

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.

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进 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目标：通过显着缩短磁场上升时间，可以显着提高梯度场引起的生物效应的阈值。在第一阶段，我们使用新颖的脉冲功率技术构建了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，使用的磁转换速率比典型临床系统中使用的磁转换速率高 200,000 倍。在第二阶段，我们将以更高的转换速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特定吸收率，建立颤动阈值，评估图像质量，并检测超高转换速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，我们将暴露的最大转换速率设置为显着低于引起动物心脏颤动的最低阈值的水平。在这项人体试验研究中，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将该技术传播到市场奠定基础，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，我们将与领先的儿科研究中心（儿童国家医疗中心）和美国著名的历史黑人大学（霍华德大学）协调努力，提供与儿科人群特别相关的产品，该群体被认为是不足的——由美国国立卫生研究院 (NIH) 服务。这项研究的监管和科学方面预计将是开创性的，揭示从未通过实验研究过的梯度机制的生物效应数据。这些发现一旦得到验证，可能会引起所有 MRI 系统制造商和用户的极大兴趣。公共卫生相关性 MRI 扫描广泛用于检查血管。许多团体正在尝试用 MRI 研究心脏。 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了可以通过某些技术消除副作用。我们将在人类身上研究这种现象。