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首页> 外文期刊>Applied Computational Electromagnetics Society journal >RF Magnetic Field Profiling with a Dielectric Bore Lining for Traveling Waves in a 3-T MRI Scanner: A Computational Study
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RF Magnetic Field Profiling with a Dielectric Bore Lining for Traveling Waves in a 3-T MRI Scanner: A Computational Study

机译：在3T MRI扫描仪中用电介质衬里对行波进行RF磁场分析的计算研究

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摘要

Traveling-wave magnetic resonance imaging (MRI) can be advantageous over the classical, quasi-static or near-field MRI. However, it is restricted to ultra-high static magnetic fields in the scanner and the correspondingly high RF excitation magnetic field frequencies due to fundamental constraints in cutoff frequencies of the MRI bore, considered as a waveguide. Through a computational study, we propose translating traveling-wave ideas to a 3-tesla scanner, where the RF magnetic field frequency is 127.8 MHz, using a high-permittivity dielectric layer (lining) that is built into the bore. With the lining, we can achieve traveling-wave modes inside the imaging phantoms even at 3 T, where this is generally not possible. We present results obtained using the higher order method of moments in the surface integral equation formulation, previously established as an efficient, accurate, and reliable technique for modeling of RF fields in MRI applications. Our simulations of a simple circularly polarized RF probe and dielectric lining give rise to a considerably uniform circularly polarized RF magnetic field inside phantoms in the clinical scanner.
机译：行波磁共振成像（MRI）可能优于经典的准静态或近场MRI。然而，由于在被视为波导器的MRI孔的截止频率中的基本限制，它被限制在扫描仪中的超高静磁场和相应较高的RF激励磁场频率。通过计算研究，我们建议使用内置在孔中的高介电常数介电层（衬里），将行波思想转换为3-特斯拉扫描仪，其中RF磁场频率为127.8 MHz。使用衬里，我们甚至可以在3 T时实现成像体模内部的行波模式，而这通常是不可能的。我们介绍了使用表面积分方程公式中的矩的高阶方法获得的结果，该方法先前已被确立为在MRI应用中建模RF场的有效，准确和可靠的技术。我们对简单的圆极化RF探针和电介质衬里的仿真在临床扫描仪的体模内部产生了相当均匀的圆极化RF磁场。

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