磁共振六通道线圈阵列的数字化仿真与设计

The Numerical Simulation and Design of a 6-Channel Array Coil for MRI

近年来,多通道线圈阵列被广泛应用于磁共振成像,以提高图像的质量。针对局部感兴趣区域内的射频场优化,提出一种由不同尺寸单元构成的六通道线圈阵列,可优化盆腔组织中局部感兴趣区域内的射频场。使用宽度为10和20 cm的两种不同尺寸的线圈单元来构建六通道线圈阵列模型,并对其采用几何重叠法和电容网络法进行去耦,以及运用时域有限差分(FDTD)方法进行仿真和计算,分析和评估其在感兴趣区域内产生的射频场。仿真结果表明,在加载盆腔组织椭圆柱电磁模型情况下,提出的线圈阵列的去耦效果S12和S13分别为-27.19和-33.46 d B,在感兴趣区域内产生的射频场B+1强度平均值,比由宽度为15 cm的相同单元构成的常规线圈阵列高出约5.21%。由不同尺寸单元构成的六通道线圈阵列能够优化感兴趣区域内的射频场,为磁共振线圈设计提供新的思路和方法。

The multi-channel array coil has been widely applied in MRI to improve the quality of images in recent years. Aimed at optimizing the radio frequency（RF） field in the local region of interest（ROI）,we proposed a model of a 6-channel array coil consisting of elements of different dimensions,which was proved to be able to optimize the RF field in the local region of interest in the pelvic cavity. The model was made up of coils with two different widths（10 cm and 20 cm）. In this paper,geometry overlapping and capacitive network methods were adopted to decouple coils,and the finite difference time domain（FDTD） method was applied to simulation and calculation. The RF field in ROI produced by the proposed array coil was analyzed and evaluated. The simulation results showed that the decoupling levels S12 and S13 of the proposed array coil combined with the elliptic cylinder electromagnetic model were-27. 19 d B and-33. 46 d B,respectively.Additionally,the RF field B＋1 mean value in ROI was approximately 5. 21% larger than a conventional array coil made up of same elements with width of 15 cm. In conclusion,the array coil made up of elements with different dimensions improved the RF field in ROI,thereby providing inspiration for the design of RF coils for MRI.