Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China; School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China; School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
Magn Reson Imaging. 2023 Feb;96:75-84. doi: 10.1016/j.mri.2022.10.008. Epub 2022 Oct 18.
In ultra-high-field (UHF) magnetic resonance imaging (MRI) applications, the design and analysis of high-frequency radio frequency (RF) coils requires full-wave electromagnetic (EM) methods that can handle complex field-tissue interactions. Using a Huygens' equivalent surface, the Method of Moments (MoM) and the Finite-Difference Time-Domain (FDTD) algorithm can be combined to accurately model the high-frequency RF coils. In previous research, a uniform FDTD mesh structure was considered, providing a compromised solution for coil-tissue interactions. This paper proposes a hybrid FDTD/MoM algorithm with non-uniform meshes. The fine mesh domain is set at the Huygens' surface, and the other domain uses coarse meshes. The proposed algorithms are strictly validated, and their computational performance is compared against conventional methods. Results show that the new algorithm can improve the calculation efficiency without losing accuracy. Specifically, compared with the uniform FDTD method, the numerical difference between both hybrid methods remains at 3.2%. Still, the calculation time of the non-uniform grid algorithm is reduced by 64.2%, demonstrating the effectiveness of the new algorithm for modeling RF coils for UHF-MRI applications.
在超高磁场（UHF）磁共振成像（MRI）应用中，高频射频（RF）线圈的设计和分析需要全波电磁（EM）方法，以处理复杂的场-组织相互作用。使用惠更斯等效面，矩量法（MoM）和时域有限差分（FDTD）算法可以结合起来，精确地模拟高频 RF 线圈。在以前的研究中，考虑了均匀的 FDTD 网格结构，为线圈-组织相互作用提供了一个折中的解决方案。本文提出了一种具有非均匀网格的混合 FDTD/MoM 算法。细网格域设置在惠更斯表面，其他域使用粗网格。提出的算法经过严格验证，并与传统方法进行了计算性能比较。结果表明，新算法可以在不损失精度的情况下提高计算效率。具体来说，与均匀 FDTD 方法相比，两种混合方法的数值差异保持在 3.2%。尽管如此，非均匀网格算法的计算时间减少了 64.2%，证明了新算法在 UHF-MRI 应用中建模 RF 线圈的有效性。
