Theoretical Investigation of Random Noise-Limited Signal-to-Noise Ratio in MR-Based Electrical Properties Tomography.
Theoretical Investigation of Random Noise-Limited Signal-to-Noise Ratio in MR-Based Electrical Properties Tomography.
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基于磁共振的电特性断层扫描中随机噪声限制信噪比的理论研究
DOI：
10.1109/tmi.2015.2427236
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发表时间：
2015-11
影响因子：
10.6
通讯作者：
Hancu I
中科院分区：
文献类型：
--
作者：
Lee SK;Bulumulla S;Hancu I
在基于磁共振成像的电性质断层扫描（MREPT）中，组织电性质（EPs）是由发射射频场（B1+）的空间变化得出的。本文从理论上推导了MREPT得到的电学性质的信噪比（SNR）与输入B1+数据的信噪比（SNR）之间的关系，假设后者远大于1，B1+中不同体素的噪声在统计上是独立的。结果表明，对于给定的B1+数据，电导率和相对介电常数的信噪比与确定EPs的感兴趣区域（ROI）线性尺寸的平方成正比，与感兴趣区域（ROI）体素数的平方根成正比。该关系还显示了信噪比随主磁场（B0）强度的变化。利用解析计算的B1+图在圆柱形体上进行了数值模拟，验证了预测的信噪比，并发现该预测可以解释文献中先前实验结果的某些方面。我们的信噪比公式可用于估计获得所需质量的组织EP图所需的最小输入数据信噪比和ROI大小。
In magnetic resonance imaging-based electrical properties tomography (MREPT), tissue electrical properties (EPs) are derived from the spatial variation of the transmit RF field (B1+). Here we derive theoretically the relationship between the signal-to-noise ratio (SNR) of the electrical properties obtained by MREPT and the SNR of the input B1+ data, under the assumption that that latter is much greater than unity, and the noise in B1+ at different voxels is statistically independent. It is shown that for a given B1+ data, the SNR of both electrical conductivity and relative permittivity is proportional to the square of the linear dimension of the region of interest (ROI) over which the EPs are determined, and to the square root of the number of voxels in the ROI. The relationship also shows how the SNR varies with the main magnetic field (B0) strength. The predicted SNR is verified through numerical simulations on a cylindrical phantom with an analytically calculated B1+ map, and is found to provide explanation of certain aspects of previous experimental results in literature. Our SNR formula can be used to estimate minimum input data SNR and ROI size required to obtain tissue EP maps of desired quality.