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的优势；特别是简而言之，高场磁体--更高的梯度强度，更低的噪音，以及更少的神经刺激。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成像技术在更高的场中表现得更好。对于通过靶向超顺磁性造影剂、扩散加权成像、骨小梁组织的高分辨率方法、快速MR血管成像技术(如Presto-Sense)和下一代超快超极化C技术实现的超高分辨率技术，似乎在更高的领域尤其需要更高的梯度性能。其中一些先进技术将取代X射线CT方法，后者最近被证明存在比之前认为的更大的癌症风险。为了更好地适应最广泛的先进MRI技术阵列，建议的梯度线圈将在针对高转换速率技术优化的配置和针对高梯度技术优化的配置之间进行切换。基于初步模拟，预计其性能如下：在1100A时，占空比为25%时，斜率为100mT/m；在1600V时，转换速率为205T/m/S；成像直径为57 cm的均匀区域，均方根为9%的非均匀性；相对残余涡流低于1%；对于3T场中典型的EPI脑序列，噪声低于100分贝；并且机械坚固性适合一些预期的超极化13C应用所需的操作，在7T以下的磁场和高达1100 A的脉冲电流下不会有电流降级。RT垫片将通过Z5以及动态ZO和Z2提供所需的修正。第一阶段将在确定完全优化的设计后，通过对所有方面的详细模拟来论证项目的可行性，并演示关键制造问题的可行解决方案。完整的线圈将在第二阶段建造和测试。

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.