Magnetic Resonance Materials in Physics Biology and Medicine ( IF 2.0 ) Pub Date : 2023-04-07 , DOI: 10.1007/s10334-023-01077-z Maxim Terekhov 1 , Ibrahim A Elabyad 1 , David Lohr 1 , Ulrich Hofmann 2 , Laura M Schreiber 1
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Introduction
MRI of excised hearts at ultra-high field strengths (\({\mathrm{B}}_{0}\)≥7 T) can provide high-resolution, high-fidelity ground truth data for biomedical studies, imaging science, and artificial intelligence. In this study, we demonstrate the capabilities of a custom-built, multiple-element transceiver array customized for high-resolution imaging of excised hearts.
Method
A dedicated 16-element transceiver loop array was implemented for operation in parallel transmit (pTx) mode (8Tx/16Rx) of a clinical whole-body 7 T MRI system. The initial adjustment of the array was performed using full-wave 3D-electromagnetic simulation with subsequent final fine-tuning on the bench.
Results
We report the results of testing the implemented array in tissue-mimicking liquid phantoms and excised porcine hearts. The array demonstrated high efficiency of parallel transmits characteristics enabling efficient pTX-based B1+-shimming.
Conclusion
The receive sensitivity and parallel imaging capability of the dedicated coil were superior to that of a commercial 1Tx/32Rx head coil in both SNR and T2*-mapping. The array was successfully tested to acquire ultra-high-resolution (0.1 × 0.1 × 0.8 mm voxel) images of post-infarction scar tissue. High-resolution (isotropic 1.6 mm3 voxel) diffusion tensor imaging-based tractography provided high-resolution information about normal myocardial fiber orientation.
中文翻译：
使用 8Tx/16Rx pTx 线圈在全身 7 T MRI 系统上对离体猪心脏进行高分辨率成像
介绍
超高场强 ( \({\mathrm{B}}_{0}\) ≥7 T) 下离体心脏的 MRI 可为生物医学研究、成像科学和人工智能。在这项研究中，我们展示了为离体心脏的高分辨率成像定制的多元件收发器阵列的功能。
方法
一个专用的 16 元件收发器环路阵列被实施用于在临床全身 7 T MRI 系统的并行传输 (pTx) 模式 (8Tx/16Rx) 中运行。阵列的初始调整是使用全波 3D 电磁模拟进行的，随后在工作台上进行最终微调。
结果
我们报告了在模拟组织的液体幻影和离体猪心中测试实施阵列的结果。该阵列展示了高效的并行传输特性，可实现高效的基于 pTX 的 B 1 +匀场。
结论
专用线圈的接收灵敏度和并行成像能力在 SNR 和 T 2 * 映射方面均优于商用 1Tx/32Rx 头部线圈。该阵列经过成功测试，可获取梗塞后疤痕组织的超高分辨率（0.1 × 0.1 × 0.8 毫米体素）图像。基于高分辨率（各向同性 1.6 mm 3体素）扩散张量成像的纤维束成像提供了有关正常心肌纤维方向的高分辨率信息。
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