Lakshmanan Karthik, Brown Ryan, Madelin Guillaume, Qian Yongxian, Boada Fernando, Wiggins Graham C
Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA.
Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University School of Medicine, New York, NY, USA.
NMR Biomed. 2018 Feb;31(2). doi: 10.1002/nbm.3867. Epub 2017 Dec 27.
The purpose of this work is to illustrate a new coil decoupling strategy and its application to a transmit/receive sodium/proton phased array for magnetic resonance imaging (MRI) of the human brain. We implemented an array of eight triangular coils that encircled the head. The ensemble of coils was arranged to form a modified degenerate mode birdcage whose eight shared rungs were offset from the z-axis at interleaved angles of ±30°. This key geometric modification resulted in triangular elements whose vertices were shared between next-nearest neighbors, which provided a convenient location for counter-wound decoupling inductors, whilst nearest-neighbor decoupling was addressed with shared capacitors along the rungs. This decoupling strategy alleviated the strong interaction that is characteristic of array coils at low frequency (32.6 MHz in this case) and allowed the coil to operate efficiently in transceive mode. The sodium array provided a 1.6-fold signal-to-noise ratio advantage over a dual-nuclei birdcage coil in the center of the head and up to 2.3-fold gain in the periphery. The array enabled sodium MRI of the brain with 5-mm isotropic resolution in approximately 13 min, thus helping to overcome low sodium MR sensitivity and improving quantification in neurological studies. An eight-channel proton array was integrated into the sodium array to enable anatomical imaging.
这项工作的目的是阐述一种新的线圈去耦策略及其在用于人脑磁共振成像（MRI）的发射/接收钠/质子相控阵中的应用。我们实现了一个由八个环绕头部的三角形线圈组成的阵列。这些线圈组合被布置成形成一个改进的简并模式鸟笼，其八个共享横档相对于z轴以±30°的交错角度偏移。这一关键的几何修改产生了三角形单元，其顶点在最近邻的下一个邻居之间共享，这为反向缠绕的去耦电感提供了一个便利的位置，而最近邻去耦则通过沿着横档的共享电容器来解决。这种去耦策略减轻了阵列线圈在低频（在这种情况下为32.6 MHz）时特有的强相互作用，并使线圈能够在收发模式下高效运行。钠阵列在头部中心比双核鸟笼线圈提供了1.6倍的信噪比优势，在外围增益高达2.3倍。该阵列能够在大约13分钟内实现5毫米各向同性分辨率的脑部钠MRI，从而有助于克服低钠MR灵敏度并改善神经学研究中的定量分析。一个八通道质子阵列被集成到钠阵列中以实现解剖成像。
