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

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.