论文标题
使用永久磁铁HALBACH阵列在50吨处体内三维大脑和肢体MRI
In vivo three-dimensional brain and extremity MRI at 50 mT using a permanent magnet Halbach array
论文作者
论文摘要
目的：设计一个低成本的基于永久磁铁的MRI系统，能够在合理的扫描时间内获取体内MR图像。 方法：一个离散的HALBACH永久磁铁阵列，其直径为27 cm的透明孔阵列设计用于50吨。在Phantoms和in Vivo上集成并测试了定制构建的梯度线圈，射频线圈，梯度放大器和射频放大器。 结果：幻影结果表明，在15 cm的视野期间，Y-和z方向的梯度非线性小于5％，不需要校正。对于X方向，它明显更大，但可以在后处理中部分纠正。在约2分钟的时间内以4x4x4 mm的空间分辨率获取了使用涡轮自旋回波序列的健康志愿者大脑的三维体内扫描。 T1加权和T2加权扫描显示出良好的组织对比度。此外，在十二分钟内以〜3x2x2 mm的空间分辨率获得了健康志愿者膝盖的体内扫描，以显示系统对肢体成像的适用性。 结论：这项工作表明，有可能在合理的数据获取时间内构建具有小于10000欧元的硬件组件的低场MRI单元，该硬件组件的成本少于10000欧元。该系统具有高度的可移植性，磁铁重量约为75千克，梯度和RF放大器各有15千克，梯度线圈10 kg，光谱仪为5千克。
Purpose: To design a low-cost, portable permanent magnet-based MRI system capable of obtaining in vivo MR images within a reasonable scan time. Methods: A discretized Halbach permanent magnet array with a clear bore diameter of 27 cm was designed for operation at 50 mT. Custom built gradient coils, radiofrequency coil, gradient amplifiers and radiofrequency amplifier were integrated and tested on both phantoms and in vivo. Results: Phantom results showed that the gradient non-linearity in the y- and z-directions was less than 5% over a 15 cm field-of-view and did not need correcting. For the x-direction, it was significantly greater, but could be partially corrected in post-processing. Three dimensional In vivo scans of the brain of a healthy volunteer using a turbo-spin echo sequence were acquired at a spatial resolution of 4x4x4 mm in a time of ~2 mins. T1-weighted and T2-weighted scans showed a good degree of tissue contrast. In addition, in vivo scans of the knee of a healthy volunteer were acquired at a spatial resolution of ~3x2x2 mm within a twelve minutes to show the applicability of the system to extremity imaging. Conclusion: This work has shown that it is possible to construct a low-field MRI unit with hardware components costing less than 10000 euros, which is able to acquire human images in vivo within a reasonable data acquisition time. The system has a high degree of portability with magnet weight ~75 kg, gradient and RF amplifiers each 15 kg, gradient coils 10 kg and spectrometer 5 kg.
