Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, D-97078 Wuerzburg, Germany; Department of Electronics and Communications Engineering, Thebes Higher Institute of Engineering, Cairo, Egypt.
Chair of Cellular and Molecular Imaging, Comprehensive Heart Failure Center (CHFC), University Hospital Wuerzburg, D-97078 Wuerzburg, Germany.
J Magn Reson. 2019 Aug;305:195-208. doi: 10.1016/j.jmr.2019.07.004. Epub 2019 Jul 5.
The design, simulation, assembly and testing of a novel dedicated antisymmetric transmit/receive (Tx/Rx) coil array to demonstrate the feasibility of cardiac magnetic resonance imaging (cMRI) in pigs at 7 T was described. The novel antisymmetric array is composed of eight elements based on mirrored and reversed loop orientations to generate varying B field harmonics for RF shimming. The central four loop elements formed together a pair of antisymmetric L-shaped channels to allow good decoupling between all neighboring elements of the entire array. The antisymmetric array was compared to a standard symmetric rectilinear loop array with an identical housing dimension. Both arrays were driven in the parallel transmit (pTx) mode forming an 8-channel transmit and 16-channel receive (8Tx/16Rx) coil array, where the same posterior array was combined with both anterior arrays. The hardware and imaging performance of the dedicated cardiac arrays were validated and compared by means of electromagnetic (EM) simulations, bench-top measurements, phantom, and ex-vivo MRI experiments with 46 kg female pig. Combined signal-to-noise ratio (SNR), geometry factor (g-factor), noise correlation maps, and high resolution ex-vivo cardiac images were acquired with an in-plane resolution of 0.3 mm × 0.3 mm using both arrays. The novel antisymmetric array enhanced the SNR within the heart by about two times and demonstrated good decoupling and improved control of the B field distributions for RF shimming compared to the standard coil array. Parallel imaging with acceleration factor (R) up to 4 was possible using the novel antisymmetric coil array while maintaining the mean g-factor within the heart region of 1.13.
描述了一种新颖的专用反相发射/接收（Tx/Rx）线圈阵列的设计、模拟、组装和测试，以证明在 7T 下对猪进行心脏磁共振成像（cMRI）的可行性。该新型反相阵列由基于镜像和反向环取向的八个元件组成，用于产生不同的 B 场谐波以进行 RF 匀场。中央的四个环形元件一起形成一对反相 L 形通道，以允许整个阵列的所有相邻元件之间具有良好的去耦。将反相阵列与具有相同外壳尺寸的标准对称直线环阵列进行了比较。两个阵列都在并行发射（pTx）模式下驱动，形成一个 8 通道发射和 16 通道接收（8Tx/16Rx）线圈阵列，其中相同的后向阵列与两个前向阵列组合。通过电磁（EM）模拟、台式测量、体模和 46kg 雌性猪的离体 MRI 实验，对专用心脏阵列的硬件和成像性能进行了验证和比较。使用这两个阵列获得了组合信噪比（SNR）、几何因子（g 因子）、噪声相关图以及高分辨率离体心脏图像，其平面分辨率为 0.3mm×0.3mm。与标准线圈阵列相比，新型反相阵列可将心脏内的 SNR 提高约两倍，并可实现良好的去耦和对 RF 匀场的 B 场分布的改进控制。使用新型反相线圈阵列可以实现高达 4 的并行成像加速因子（R），同时保持心脏区域的平均 g 因子在 1.13 以内。
