Dielectric resonators made of high permittivity materials with low losses have been extensively studied for application in magnetic resonance imaging (MRI) and magnetic resonance spectroscopy. They can focus, redistribute, and enhance the radio frequency magnetic field in a controlled way. In this Letter, we investigate coupled very-high permittivity dielectric resonators for clinical bilateral breast MRI. The resonators are tuned to support a TE mode within the frequency of 3 T MRI and implemented as a pair of coaxial hollow cylinders consisting of ceramic rings with extremely high permittivity (e ∼ 870) and low loss. We study the electromagnetic coupling between two resonators placed in the near field and analyze the impact of symmetric and antisymmetric mode excitation on the sensitivity of the MRI machine. We experimentally verify that the coupling of the mode with symmetric field distribution to the radio frequency body birdcage coil allows us to enhance the receive sensitivity substantially and to decrease the excitation power needed to provide the optimal transmit efficiency, thus making the MRI procedure safer. Our work offers a practical method to realize a simple yet very effective system based on dielectric resonators for bilateral breast imaging.

中文翻译：

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用于临床 MRI 的耦合极高介电常数介电谐振器

由具有低损耗的高介电常数材料制成的介电谐振器已被广泛研究用于磁共振成像 (MRI) 和磁共振波谱。它们可以以可控的方式聚焦、重新分配和增强射频磁场。在这封信中，我们研究了用于临床双侧乳腺 MRI 的耦合极高介电常数介电谐振器。谐振器经过调谐以支持 3 T MRI 频率内的 TE 模式，并作为一对同轴空心圆柱体实现，该圆柱体由具有极高介电常数 (e ∼ 870) 和低损耗的陶瓷环组成。我们研究了放置在近场中的两个谐振器之间的电磁耦合，并分析了对称和反对称模式激励对 MRI 机器灵敏度的影响。我们通过实验验证了具有对称场分布的模式与射频体鸟笼线圈的耦合使我们能够显着提高接收灵敏度并降低提供最佳传输效率所需的激励功率，从而使 MRI 过程更安全。我们的工作提供了一种实用的方法来实现基于介电谐振器的简单但非常有效的双侧乳房成像系统。