IEEE Trans Med Imaging. 2015 May;34(5):1148-54. doi: 10.1109/TMI.2014.2377792. Epub 2014 Dec 5.
A numerical method is shown for calculating the noise correlation coefficient in arrays of magnetic resonance imaging (MRI) coils loaded with capacitively-loaded ring metamaterial lenses, and in the presence of a conducting half-space resembling a sample. This numerical method is validated by comparison with experimental results obtained in two different experimental procedures for double check: noise resistance measurements with a network analyzer and noise correlation measurements in an MRI system. It is found that, for practical array configurations such as overlapping coils or capacitively-decoupled coils, the noise correlation coefficient turns negative for coils loaded with metamaterial lenses. In particular, the analysis is carried out with metamaterial structures known as magnetoinductive lenses, which have been demonstrated in previous works to improve the signal-to-noise ratio of MRI coils. Results are also shown to demonstrate that negative noise correlations have as an effect the improvement of the g-factor in coil arrays for parallel MRI.
一种数值方法被展示用于计算磁共振成像（MRI）线圈阵列中加载电容加载环超材料透镜的噪声相关系数，并在存在类似于样品的导电半空间的情况下。该数值方法通过与网络分析仪进行的噪声电阻测量和 MRI 系统中的噪声相关测量的两种不同实验程序的实验结果进行比较得到验证。结果表明，对于重叠线圈或电容去耦线圈等实际的阵列配置，加载超材料透镜的线圈的噪声相关系数变为负值。特别地，分析是使用先前工作中已经证明可以提高 MRI 线圈的信噪比的磁导透镜之类的超材料结构进行的。结果还表明，负噪声相关具有改善平行 MRI 中线圈阵列的 g 因子的效果。
