IEEE Trans Biomed Eng. 2014 Feb;61(2):327-33. doi: 10.1109/TBME.2013.2250973.
Multi-element volume radio-frequency (RF) coils are an integral aspect of the growing field of high-field magnetic resonance imaging. In these systems, a popular volume coil of choice has become the transverse electromagnetic (TEM) transceiver coil consisting of microstrip resonators. In this paper, to further advance this design approach, a new microstrip resonator strategy in which the transmission line is segmented into alternating impedance sections, referred to as stepped impedance resonators (SIRs), is investigated. Single-element simulation results in free space and in a phantom at 7 T (298 MHz) demonstrate the rationale and feasibility of the SIR design strategy. Simulation and image results at 7 T in a phantom and human head illustrate the improvements in a transmit magnetic field, as well as RF efficiency (transmit magnetic field versus specific absorption rate) when two different SIR designs are incorporated in 8-element volume coil configurations and compared to a volume coil consisting of microstrip elements.
多元素容积射频 (RF) 线圈是高场磁共振成像这一日益发展的领域不可或缺的一部分。在这些系统中，一种流行的容积线圈选择是由微带谐振器组成的横电磁 (TEM) 收发线圈。在本文中，为了进一步推进这种设计方法，研究了一种新的微带谐振器策略，其中传输线被分成交替的阻抗部分，称为阶梯阻抗谐振器 (SIR)。在自由空间和 7 T（298 MHz）幻影中的单元素模拟结果证明了 SIR 设计策略的原理和可行性。在幻影和人头上的 7 T 的模拟和图像结果说明了当将两种不同的 SIR 设计结合到 8 元件容积线圈配置中并与由微带元件组成的容积线圈进行比较时，在发射磁场以及 RF 效率（发射磁场与比吸收率）方面的改进。
