University of Pittsburgh, Department of Bioengineering, Pittsburgh, PA, United States of America.
Siemens Medical Solutions, New York, NY, United States of America.
PLoS One. 2019 Jan 10;14(1):e0209663. doi: 10.1371/journal.pone.0209663. eCollection 2019.
A variety of 7 Tesla RF coil systems have been proposed to produce spin excitation (B1+ field) and MR image acquisition. Different groups have attempted to mitigate the challenges at high and ultra-high field MRI by proposing novel hardware and software solutions to obtain uniformly high spin excitation at acceptable RF absorption levels. In this study, we extensively compare the designs of two distributed-circuit based RF coils: the Tic-Tac-Toe (TTT) head coil and TEM head coil on multiple anatomically detailed head models and in-vivo. Bench measurements of s-parameters and experimental B1+ field distribution were obtained in volunteers and compared with numerical simulations. RF absorption, quantified by both average and peak SAR, and B1+ field intensity and homogeneity, calculated/measured in terms of maximum over minimum and coefficient of variation (CV) in the region of interest (ROI), are presented for both coils. A study of the RF consistency of both coils across multiple head models for different RF excitation strategies is also presented.
已经提出了多种 7 特斯拉射频线圈系统来产生自旋激发（B1+场）和磁共振图像采集。不同的研究小组试图通过提出新的硬件和软件解决方案来克服高场和超高场 MRI 的挑战，以在可接受的射频吸收水平下获得均匀的高自旋激发。在这项研究中，我们在多个解剖细节的头部模型和体内对基于分布式电路的两种射频线圈的设计进行了广泛的比较：Tic-Tac-Toe（TTT）头部线圈和 TEM 头部线圈。在志愿者中进行了 s 参数和实验 B1+场分布的基准测量，并与数值模拟进行了比较。分别以平均和峰值 SAR 以及 ROI 中最大值与最小值之比和变异系数（CV）来表示射频吸收率、B1+场强度和均匀性。还呈现了两种线圈在不同射频激发策略下对多个头部模型的射频一致性研究。
