Human Brain Research Center, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Quality Electrodynamics, Mayfield Village, Ohio, USA.
Magn Reson Med. 2022 Mar;87(3):1613-1620. doi: 10.1002/mrm.29062. Epub 2021 Nov 1.
To demonstrate the capability of insertable inductively coupled volumetric coils for MR microscopy in a human 7T MR system.
Insertable inductively coupled volume coils with diameters of 26 and 64 mm (D26 and D64 coils) targeted for monkey and mouse brain specimen sizes were designed and fabricated. These coils were placed inside the imaging volume of a transmit/receive knee coil without wired connections to the main system. Signal-to-noise ratio (SNR) evaluations were conducted with and without the insertable coils, and the g-factor maps of parallel imaging (PI) were also calculated for the D64 coil. Brain specimens were imaged using 3D -weighted images with spatial resolution of isotropic 50 and 160 μm using D26 and D64 coils, respectively.
Relative average (SD) SNRs compared with knee coil alone were 12.54 (0.30) and 2.37 (0.05) at the center for the D26 and D64 coils, respectively. The mean g-factors of PI with the D64 coil for the factor of 2 were less than 1.1 in the left-right and anterior-posterior directions, and around 1.5 in the superior-inferior direction or when the PI factor of 3 was used. Acceleration in two directions showed lower g-factors but suffered from intrinsic low SNR. Representative -weighted images of the specimen showed structural details.
Inductively coupled small diameter coils insertable to the knee coil demonstrated high SNR and modest PI capability. The concept was successfully used to visualize fine structures of the brain specimen. The insertable coils are easy to handle and enable MR microscopy in a human whole-body 7T MRI system.
在人体 7T MR 系统中展示可插入式感应耦合容积线圈在 MR 显微镜中的性能。
设计并制作了直径为 26 和 64 毫米（D26 和 D64 线圈）的可插入感应耦合容积线圈，用于猴脑和鼠脑标本。这些线圈放置在发射/接收膝关节线圈的成像体积内，与主系统没有有线连接。在有无可插入线圈的情况下进行了信噪比（SNR）评估，并计算了 D64 线圈的并行成像（PI）的 g 因子图。使用 D26 和 D64 线圈分别对脑标本进行了空间分辨率各向同性为 50 和 160μm 的 3D 加权图像成像。
与单独膝关节线圈相比，D26 和 D64 线圈中心的相对平均（SD）SNR 分别为 12.54（0.30）和 2.37（0.05）。使用 D64 线圈进行 PI 时，因子为 2 的平均 g 因子在左右和前后方向上小于 1.1，在上下方向上约为 1.5，或当 PI 因子为 3 时。两个方向的加速显示出较低的 g 因子，但受到固有低 SNR 的影响。标本的代表性 加权图像显示了结构细节。
可插入膝关节线圈的感应耦合小直径线圈具有高 SNR 和适度的 PI 能力。该概念成功地用于可视化脑标本的精细结构。可插入线圈易于操作，并可在人体全身 7T MRI 系统中实现 MR 显微镜。
