Two 16-element radio frequency (RF) transceiver antisymmetric coil arrays with two different implementation designs aiming for improved characteristics for static phase $B_{1}^{+}$ shimming and parallel receive were developed for human cardiac MRI at 7 T. Both cardiac arrays consist of a weakly curved lightweight housing fit to an average human thorax shape as an anterior array in combination with a flat posterior array. The first array (Design 1) comprised eight identical antisymmetric loops for both anterior and posterior sections. Based on initial testing and to improve parallel imaging capabilities and $B_{1}^{+}$ field homogeneity, the second array (Design 2) was composed of 12-loops for the anterior section and four antisymmetric loops of larger size for the posterior section. Electromagnetic-field (EMF) simulations were carried out for both antisymmetric arrays loaded with an elliptical-shaped thorax phantom and two human voxel models (Duke and Ella). Static phase $B_{1}^{+}$ shimming has been carried out within Duke and Ella models using two optimization cost functions aiming to maximize the transmit efficiency and weighted combination of both $B_{1}^{+}$ field homogeneity and efficiency. The hardware and imaging performance of the two developed antisymmetric cardiac arrays was validated through EMF simulations, benchtop measurements, and MR measurements in a thorax phantom. Both antisymmetric arrays were compared to two commercial 16-element transceiver arrays (a 1Tx/16Rx in single transmit mode and an 8Tx/16Rx in parallel transmit mode). MRI measurements were performed with Design 2 using a 70-kg fresh pig cadaver (10–15 min postmortem). Parallel imaging with an acceleration factor up to $R = 6$ was possible using Design 2 while maintaining a mean g-factor of 1.47 within the pig heart. $T_{2}^{\ast }$ -weighted images of the pig heart were acquired using up to $R = 5$ with a spatial resolution of $0.35 \times 0.35 \times 4$ mm3.

中文翻译：

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用于 7 T 并行传输人体心脏 MRI 的两个 16 元件反对称收发器线圈阵列的设计与实现


两个 16 元件射频 (RF) 收发器反对称线圈阵列具有两种不同的实现设计，旨在改进静态相位 $B_{1}^{+}$ 匀场和并行接收的特性，专为 7 T 下的人体心脏 MRI 开发。心脏阵列由一个微弱弯曲的轻型外壳组成，适合人类平均胸部形状，作为前部阵列与平坦的后部阵列相结合。第一个阵列（设计 1）由前段和后段的八个相同的反对称环组成。基于初步测试，为了提高并行成像能力和 $B_{1}^{+}$ 场均匀性，第二个阵列（设计 2）由用于前部的 12 个环和用于后部的四个较大尺寸的反对称环组成。后段。对装载椭圆形胸部模型和两个人体体素模型（Duke 和 Ella）的反对称阵列进行了电磁场 (EMF) 模拟。静态相位 $B_{1}^{+}$ 匀场已在 Duke 和 Ella 模型中使用两个优化成本函数进行，旨在最大化传输效率和 $B_{1}^{+}$ 场均匀性的加权组合和效率。两个开发的反对称心脏阵列的硬件和成像性能通过 EMF 模拟、台式测量和胸部模型中的 MR 测量进行了验证。将两个反对称阵列与两个商用 16 元件收发器阵列（单发射模式下的 1Tx/16Rx 和并行发射模式下的 8Tx/16Rx）进行比较。使用设计 2 使用 70 公斤新鲜猪尸体（尸检 10-15 分钟）进行 MRI 测量。 使用设计 2 可以实现加速因子高达 $R = 6$ 的并行成像，同时保持猪心脏内的平均 g 因子为 1.47。使用高达 $R = 5$ 的空间分辨率为 $0.35 \times 0.35 \times 4$ mm3 获取猪心脏的 $T_{2}^{\ast }$ 加权图像。