Practical design of a 4 Tesla double-tuned RF surface coil for interleaved 1H and 23Na MRI of rat brain
Practical design of a 4 Tesla double-tuned RF surface coil for interleaved 1H and 23Na MRI of rat brain
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DOI：
10.1016/j.jmr.2006.04.011
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发表时间：
2006-08-01
影响因子：
2.2
通讯作者：
Shah, N. J.
中科院分区：
文献类型：
--
作者：
Alecci, M.;Romanzetti, S.;Shah, N. J.
MRI被证明是中风、缺血和癌症动物模型中钠定量的非常有用的工具。在这项工作中，我们提出了一个双频RF表面线圈，提供H-1和Na-23图像的大鼠头部在4 T的实际设计。双频RF表面线圈由调谐到H-1频率的大环路和调谐到Na-23频率的较小共面环路组成。通过在较小的线圈中插入陷波电路，消除了两个环路之间的互耦。这种独立环路设计是通用的，因为它能够单独优化两个线圈的灵敏度和RF场分布。为了使这种简单的双调谐线圈设计容易扩展到其他频率（核）和尺寸，我们详细描述了工作台设计和MRI测试的实际方面，使用模拟体内条件的体模。我们的独立环路，双调谐线圈和单调谐Na-23线圈的大小相同，在体内条件下获得的体模匹配之间的比较，显示了减少的Na-23的灵敏度（约28%），因为在陷阱电感的信号损耗。还报告了典型的一致H-1和Na-23大鼠脑图像，显示出良好的SNR（Na-23：脑7，脑室脑脊液11）和空间分辨率（Na-23：1.25 x 1.25 x 5 mm（3））。使用该线圈获得的体内SNR值与文献中的其他当代设计相当（如果不是更好的话）。(c)2006年爱思唯尔公司All rights reserved.
MRI is proving to be a very useful tool for sodium quantification in animal models of stroke, ischemia, and cancer. In this work, we present the practical design of a dual-frequency RF surface coil that provides H-1 and Na-23 images of the rat head at 4 T. The dual-frequency RF surface coil comprised of a large loop tuned to the H-1 frequency and a smaller co-planar loop tuned to the Na-23 frequency. The mutual coupling between the two loops was eliminated by the use of a trap circuit inserted in the smaller coil. This independent-loop design was versatile since it enabled a separate optimisation of the sensitivity and RF field distributions of the two coils. To allow for an easy extension of this simple double-tuned coil design to other frequencies (nuclei) and dimensions, we describe in detail the practical aspects of the workbench design and MRI testing using a phantom that mimics in vivo conditions. A comparison between our independent-loop, double-tuned coil and a single-tuned Na-23 coil of equal size obtained with a phantom matching in vivo conditions, showed a reduction of the Na-23 sensitivity (about 28%) because of signal losses in the trap inductance. Typical congruent H-1 and Na-23 rat brain images showing good SNR (Na-23: brain 7, ventricular cerebrospinal fluid 11) and spatial resolution (Na-23: 1.25 x 1.25 x 5 mm(3)) are also reported. The in vivo SNR values obtained with this coil were comparable to, if not better than, other contemporary designs in the literature. (c) 2006 Elsevier Inc. All rights reserved.