IEEE Trans Med Imaging. 2018 Jul;37(7):1723-1732. doi: 10.1109/TMI.2018.2812151.
The RF receive coil array has become increasingly vital in current MR imaging practice due to its extended spatial coverage, maintained high SNR, and improved capability of accelerating data acquisition. The performance of a coil array is intrinsically determined by the current patterns generated in coil elements as well as by the induced electromagnetic fields inside the object. Investigations of the ultimate performance constrained by a specific coil space, which defines all possible current patterns flowing within, offer the opportunity to evaluate coil-space parameters (i.e., coverage, coil-to-object distance, layer thickness, and coil element type) without the necessity of considering the realistic coil element geometry, coil elements layout, and number of receive channels in modeling. In this paper, to mimic 7-T monkey RF head coil design, seven hypothetical ultimate coil arrays with different coil-space configurations were mounted over a numerical macaque head model; by using Huygens's surface approximation method, the influences of coil-space design parameters were systematically investigated through evaluating the spatial constrained ultimate intrinsic SNR and ultimate g-factor. Moreover, simulations were also conducted by using four coil arrays with limited number of loop-only elements, in order to explore to what extent the ultimate coil performance can be achieved by using practical coil designs, and hence several guidelines in RF coil design for monkey brain imaging at 7 T have been tentatively concluded. It is believed that the present analysis will offer important implications in novel receive array design for monkey brain MR imaging at ultra-high field.
由于其扩展的空间覆盖范围、保持的高 SNR 和改进的数据采集加速能力，射频接收线圈阵列在当前的磁共振成像实践中变得越来越重要。线圈阵列的性能本质上取决于线圈元件中产生的电流模式以及物体内部感应的电磁场。对特定线圈空间（定义了所有可能的电流模式）所限制的最终性能的研究提供了评估线圈空间参数（即覆盖范围、线圈到物体的距离、层厚度和线圈元件类型）的机会，而无需考虑实际的线圈元件几何形状、线圈元件布局和接收通道数量在建模中的情况。在本文中，为了模拟 7-T 猴头射频线圈设计，在数值化的猕猴头部模型上安装了七个具有不同线圈空间配置的假设性终极线圈阵列；通过使用惠更斯面近似方法，通过评估空间受限的最终固有 SNR 和最终 g 因子，系统地研究了线圈空间设计参数的影响。此外，还通过使用具有有限数量的仅环形元件的四个线圈阵列进行了模拟，以探讨在多大程度上可以通过实际的线圈设计实现最终线圈性能，从而初步得出了在 7 T 下进行猴脑成像的射频线圈设计的一些准则。相信本分析将为超高场猴脑磁共振成像的新型接收阵列设计提供重要启示。
