一种实现低场轻量化永磁MRI磁体系统的新策略，该系统具有良好的磁场均匀性和低涡流特性
A novel strategy for achieving a low-field lightweight permanent MRI magnet system with good magnetic field homogeneity and low eddy current
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中文总结 AI 辅助
该研究针对低场轻量化永磁MRI系统的涡流与均匀性问题，采用各向异性Sm-Fe-N粘结磁体，实现低涡流与高均匀性，成像效果优异。
中文摘要 AI 辅助
在由烧结Nd-Fe-B或Sm-Co磁体构建的低场、轻量化、无磁极永磁MRI系统中，梯度场的快速切换易在烧结磁体中感应出涡流，进而导致图像伪影。为解决该问题，我们首次报道了一种基于各向异性Sm-Fe-N粘结磁体的Sm-Fe-N永磁MRI系统，其高电阻率使X、Y、Z方向的涡流分别降低至0.093%、0.172%和2.38%，同时在直径220mm的球形体积（DSV）边界处实现了低于150ppm的磁场不均匀性。与烧结Nd-Fe-B和Sm-Co磁体相比，采用Sm-Fe-N粘结磁体作为静磁场源不仅能抑制涡流，还可实现紧密排列、高密度的磁路布局，为MRI系统提供更均匀的静磁场。无明显几何失真和条带伪影的成像结果进一步表明，该Sm-Fe-N磁体系统具有低涡流和高静磁场均匀性的优势。
英文摘要
In low-field, lightweight, pole-pieceless permanent-magnet MRI systems built with sintered Nd-Fe-B or Sm-Co magnets, the rapid switching of gradient fields readily induces eddy currents in the sintered magnets, leading to image artifacts. To address this, we report for the first time a Sm-Fe-N permanent-magnet MRI system based on anisotropic Sm-Fe-N bonded magnets, whose high electrical resistivity reduces the eddy currents in the X, Y and Z directions to 0.093%, 0.172% and 2.38%, respectively, while a magnetic field inhomogeneity below 150 ppm is achieved at the boundary of a 220 mm diameter of spherical volume (DSV). Compared with sintered Nd-Fe-B and Sm-Co magnets, using Sm-Fe-N bonded magnets as the source of the static magnetic field not only suppresses eddy currents but also makes a closely tiled, densely packed magnetic-circuit layout feasible, providing a more uniform static magnetic field for the MRI system. Imaging results free of obvious geometric distortion and banding artifacts further indicate that the Sm-Fe-N magnet system delivers low eddy currents and high static magnetic field homogeneity.
