Pennsylvania State College of Medicine, Department of Radiology, Hershey, Pennsylvania, USA.
Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA.
Magn Reson Med. 2018 May;79(5):2842-2851. doi: 10.1002/mrm.26943. Epub 2017 Sep 25.
Incorporating high dielectric constant (HDC) materials into radiofrequency (RF) coils has been shown to effectively improve RF coil performance at 7 and 3 T because of the induced displacement current in the high dielectric constant materials. The displacement current is proportional to the RF field frequency and permittivity of the material. The aim of this paper is to investigate the effect of high dielectric constant materials with even greater permittivity on the RF field at 1.5 T and 3 T.
Several monolithic ceramic materials with an ultrahigh dielectric constant ranging from 1200 to 3300 were investigated at 1.5 T and 3 T with phantom and human brain imaging along with computer modeling.
Experimental measurements in phantom studies showed a significant enhancement of signal-to-noise ratio (50-100%) and strong transmission power reduction (3-27-fold). Under suboptimal experimental conditions in this study, the signal-to-noise ratio in the human brain cortex was nearly doubled, which produced high-resolution image without the associated stronger magnetic susceptibility artifacts and elevated specific absorption rate concerns at higher field strengths.
Use of ultrahigh dielectric constant ceramic materials is a simple and low-cost approach that could further improve the RF technology to maximize image signal-to-noise ratio and reduce RF energy deposition for human studies. Magn Reson Med 79:2842-2851, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
在射频（RF）线圈中加入高介电常数（HDC）材料，已被证明可以有效地提高 7 和 3 T 时的 RF 线圈性能，这是因为高介电常数材料中的感应位移电流。位移电流与 RF 场频率和材料的介电常数成正比。本文的目的是研究具有更高介电常数的高介电常数材料对 1.5 T 和 3 T 时 RF 场的影响。
在 1.5 T 和 3 T 下，使用体模和人脑成像以及计算机建模对介电常数高达 1200 至 3300 的几种整体陶瓷材料进行了研究。
体模研究中的实验测量显示信号噪声比（50-100%）显著增强，传输功率大幅降低（3-27 倍）。在本研究中，实验条件不理想的情况下，人脑皮层的信号噪声比几乎提高了一倍，在更高场强下产生了高分辨率图像，而不会产生更强的磁敏感性伪影和更高的特定吸收率。
使用超高介电常数陶瓷材料是一种简单且低成本的方法，可以进一步改进 RF 技术，以最大限度地提高图像信号噪声比并减少人体研究中的 RF 能量沉积。磁共振医学 79:2842-2851, 2018. © 2017 国际磁共振学会。
