Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA.
Magn Reson Med. 2012 Apr;67(4):965-78. doi: 10.1002/mrm.23073. Epub 2011 Aug 19.
Traveling-wave magnetic resonance imaging utilizes far fields of a single-piece patch antenna in the magnet bore to generate radio frequency fields for imaging large-size samples, such as the human body. In this work, the feasibility of applying the "traveling-wave" technique to parallel imaging is studied using microstrip patch antenna arrays with both the numerical analysis and experimental tests. A specific patch array model is built and each array element is a microstrip patch antenna. Bench tests show that decoupling between two adjacent elements is better than -26-dB while matching of each element reaches -36-dB, demonstrating excellent isolation performance and impedance match capability. The sensitivity patterns are simulated and g-factors are calculated for both unloaded and loaded cases. The results on B 1- sensitivity patterns and g-factors demonstrate the feasibility of the traveling-wave parallel imaging. Simulations also suggest that different array configuration such as patch shape, position and orientation leads to different sensitivity patterns and g-factor maps, which provides a way to manipulate B(1) fields and improve the parallel imaging performance. The proposed method is also validated by using 7T MR imaging experiments.
行波磁共振成像利用单个贴片天线在磁体孔中的远场产生射频场，用于对大型样本（如人体）进行成像。在这项工作中，使用微带贴片天线阵列通过数值分析和实验测试研究了将“行波”技术应用于并行成像的可行性。建立了一个特定的贴片阵列模型，每个阵列元件都是微带贴片天线。台架测试表明，两个相邻元件之间的解耦优于-26dB，而每个元件的匹配达到-36dB，显示出出色的隔离性能和阻抗匹配能力。模拟了灵敏度模式并计算了空载和加载情况下的 g 因子。空载和加载情况下的 B1 灵敏度模式和 g 因子的结果证明了行波并行成像的可行性。模拟还表明，不同的阵列配置，如贴片形状、位置和方向，会导致不同的灵敏度模式和 g 因子图，这为操纵 B(1)场和提高并行成像性能提供了一种方法。该方法还通过使用 7T MR 成像实验进行了验证。
