A High-Performance Quiet Gradient Coil for High-field Whole-body MRI

描述（由申请人提供）：初步数据表明，一种完全不同的MRI梯度线圈设计方法在所有方面都具有实质性优势；特别是在短，高场磁体-更高的梯度强度，减少噪音，减少神经刺激。全身MRI梯度线圈技术的重大进步将对该领域产生根本性的好处，因为它将使一系列先进的、高速的成像技术在更高的领域表现得更好。更高的梯度性能似乎特别需要在更高的领域实现超高分辨率技术，如靶向超顺磁造影剂、弥散加权成像、高分辨率小梁骨组织方法、快速磁共振血管成像技术（如PRESTO-SENSE）和下一代超快速超极化C技术。其中一些先进的技术将取代x射线CT方法，而x射线CT方法最近被证明比以前认为的癌症风险要大得多。为了最好地适应最广泛的先进MRI技术，所提出的梯度线圈将在高回转率技术优化的配置和高梯度技术优化的配置之间切换。根据初步模拟，预期以下性能：在1100 A， 25%占空比下，梯度为100 mT/m；1600 V时的转率为205 T/m/s；57 cm区域均匀成像直径，9% rms不均匀性；相对剩余涡流小于1%；典型EPI脑序列在3t场中的噪声小于100 dB；机械稳健性强，适合在高达7 T的磁场和高达1100 A的脉冲电流下无电流衰减的情况下运行，如一些预期的超极化13C应用所需要的。RT垫片将提供所需的修正通过Z5，加上动态ZO和Z2。第一阶段将在完全优化设计确定后，通过详细的各方面模拟来证明项目的可行性，并演示关键制造问题的可行解决方案。整个线圈将在第二阶段进行建造和测试。

DESCRIPTION (provided by applicant): Preliminary data demonstrate that a radically different approach to MRI gradient coil design permits substantial advantages in all respects; especially in short, high-field magnets - higher gradient strength, reduced acoustic noise, and reduced nerve stimulation. A major advance in whole-body MRI gradient coil technology would be of fundamental benefit to the field, as it will enable a wide array of advanced, high-speed imaging techniques to perform better at higher fields. The higher gradient performance seems especially needed at higher fields for ultra-high resolution techniques enabled by targeted super-paramagnetic contrast agents, diffusion-weighted imaging, high-resolution methods for trabecular bone tissue, fast MR angiography techniques such as PRESTO-SENSE, and next-generation ultra-fast hyperpolarized C techniques. Some of these advanced techniques will supplant x-ray CT methods, which have very recently been shown to present much greater cancer risk than previously thought. To best accommodate the widest array of advanced MRI techniques, the proposed gradient coil will be switchable between a configuration optimized for high-slew-rate techniques and one optimized for high-gradient techniques. Based on preliminary simulations, the following performance is expected: 100 mT/m gradient at 1100 A, 25% duty cycle; slew rate of 205 T/m/s at 1600 V; 57 cm Region of Uniformity imaging diameter with 9% rms non-uniformity; relative residual eddy currents under 1%; acoustic noise below 100 dB for a typical EPI brain sequence in a 3 T field; and mechanical robustness suitable for operation with no current de-rating at fields up to 7 T and pulse currents up to 1100 A, as needed for some anticipated hyperpolarized 13C applications. The RT shims will provide the corrections required through Z5, plus dynamic ZO and Z2. The Phase I will demonstrate project feasibility with detailed simulations of all aspects after a fully optimized design is determined, plus demonstration of viable solutions to the key manufacturing issues. The complete coil will be constructed and tested during Phase II.