Design and performance issues of RF coils utilized in ultra high field MRI: Experimental and numerical evaluations
Design and performance issues of RF coils utilized in ultra high field MRI: Experimental and numerical evaluations
复制标题
DOI：
10.1109/tbme.2005.847564
复制
发表时间：
2005-07-01
影响因子：
4.6
通讯作者：
Chakeress, DW
中科院分区：
文献类型：
--
作者：
Ibrahim, TS;Kangarlu, A;Chakeress, DW
在本文中，两个TEM谐振器在8特斯拉（T）（340 MHz的H-1成像）进行了实验和数值评估。弹簧圈的长度为21.2 cm（标准）和11 cm（建议的幽闭恐惧症较少的设计）。使用超高场、8 T、全身磁体在单个尸体上进行实验评价。使用内部有限差分时域软件包进行数值建模，该软件包将线圈和负载（解剖学详细的人体头部模型）视为单个系统。在相对于人头部的不同线圈对准位置处，使用正交激励对线圈进行测试。对于8 T下的头部成像，整体数值和实验结果表明，与较长线圈相比，较短线圈在两种线圈结构内的生物区域中提供了上级的信噪比、线圈灵敏度和激发场。RF（激励/接收场）均匀性研究显示，两个线圈的性能存在差异，主要取决于感兴趣区域和线圈相对于头部的位置。因此，根据应用，可以有效地利用较短的线圈。
In this paper, two TEM resonators were evaluated experimentally and numerically at 8 tesla (T) (340 MHz for H-1 imaging). The coils were constructed to be 21.2-cm long (standard) and 11-cm long (a proposed less claustrophobic design). The experimental evaluation was done on a single cadaver using an ultra high field, 8 T, whole-body magnet. The numerical modeling was performed using an in-house finite difference time domain packagethat treats the coil and the load (anatomically detailed human head model) as a single system. The coils were tested with quadrature excitation at different coil alignment positions with respect to human head. For head imaging at 8 T, the overall numerical and experimental results demonstrated that when compared to the longer coil, the shorter coil provides superior signal-to-noise ratio, coil sensitivity, and excite field in the biological regions that lie within both of the coils' structures. A study of the RF (excite/receive fields) homogeneity showed variations in the performance of both coils that are mostly dependant on the region of interest and the position of coil with respect to the head. As such, depending on the application, the shorter coil could be effectively utilized.