IEEE Trans Med Imaging. 2023 May;42(5):1424-1430. doi: 10.1109/TMI.2022.3228305. Epub 2023 May 2.
MR measurement using a combination of X-nuclei and proton MRI is of great interest as the information provided by the two nuclei is highly complementary, with the X-nuclei signal giving metabolic data relating to potential biomarkers and the proton signal affording anatomical details. Due to the relatively weak signal obtained from X-nuclei, combining an X-nuclei coil with a proton coil is also advantageous for [Formula: see text] shimming and scout images. One approach to building a double-resonant coil is to modify the coil geometry. Here, to achieve double-resonance, a 2× 1 ladder network was designed and tuned at both proton and X-nuclei frequencies successfully. Due to coupling between closed wires, the double-tuned coil generates a shifted transmit efficiency pattern compared to that of the single-tuned loop at the 7T MRI proton frequency. To compensate for the shifted pattern, one part of the 2× 1 ladder network was folded, and the tuning and performance of the folded double-tuned coil were evaluated in simulations and MR measurements. The proposed structure was further evaluated with overlapped decoupling in a receive-only array. The results show that our proposed folded double-tuned coil moderated the shifted pattern of a straight double-tuned loop coil and provided minimum losses at both proton and X-nuclei frequencies. The proposed folded double-tuned loop coil has also been further extended to a receive-only array.
使用 X 核和质子 MRI 组合进行磁共振测量非常有趣，因为这两种核提供的信息高度互补，X 核信号提供与潜在生物标志物相关的代谢数据，而质子信号提供解剖细节。由于从 X 核获得的信号相对较弱，因此将 X 核线圈与质子线圈结合使用对于[公式：请参见文本]匀场和扫描图像也很有优势。构建双共振线圈的一种方法是修改线圈几何形状。在这里，为了实现双共振，设计并成功调谐了 2×1 梯型网络，使其在质子和 X 核频率下都能达到共振。由于闭合导线之间的耦合，与单调谐环路相比，双调谐线圈在 7T MRI 质子频率下产生了传输效率的偏移图案。为了补偿偏移图案，将 2×1 梯型网络的一部分折叠，并在模拟和磁共振测量中评估了折叠双调谐线圈的调谐和性能。该结构进一步在接收仅用的阵列中进行了重叠去耦评估。结果表明，我们提出的折叠双调谐线圈缓和了直双调谐线圈的偏移图案，并在质子和 X 核频率下都提供了最小的损耗。所提出的折叠双调谐线圈还进一步扩展到接收仅用的阵列。
