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首页> 外文期刊>IEEE Transactions on Magnetics >A Numerical Study on Conductivity Estimation of the Human Head in the Low Frequency Domain Using Induced Current MR Phase Imaging EIT With Multiple Gradients
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A Numerical Study on Conductivity Estimation of the Human Head in the Low Frequency Domain Using Induced Current MR Phase Imaging EIT With Multiple Gradients

机译:利用多梯度感应电流MR相位成像EIT进行低频人头电导率估计的数值研究

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摘要

An accurate conductivity estimation of human brain tissues is important for the correct diagnosis and therapy of neurological diseases. These values are patient-specific and vary naturally with the frequency. Nevertheless, they are often approximated by a constant value. Induced current magnetic resonance-electrical impedance tomography (ICMR-EIT) is a possible technique for non-invasive conductivity reconstruction in the low frequency domain. This paper presents a novel ICMR-EIT based method that uses the difference of two MR phase images. These images are obtained by gradient echo sequences with and without switching an eddy-current induction gradient. We propose the use of multiple gradients with different time periods, so that only a single parameter per tissue needs to be estimated with conservation of the frequency dependence. A numerical study on a spherical head model with four tissues investigates the feasibility of estimating conductivity values and shows that the proposed technique can successfully reconstruct these conductivity values. Furthermore, the influence of the material model and the number of harmonics associated to the gradient is investigated, together with performance of the proposed technique in the presence of noise.
机译:准确估计人脑组织的电导率对于正确诊断和治疗神经系统疾病很重要。这些值是特定于患者的,并随频率自然变化。然而,它们通常以恒定值近似。感应电流磁共振-电阻抗层析成像(ICMR-EIT)是一种用于低频域无创电导率重建的可能技术。本文提出了一种新颖的基于ICMR-EIT的方法,该方法利用了两个MR相位图像的差异。这些图像是通过在有和没有切换涡流感应梯度的情况下通过梯度回波序列获得的。我们建议使用具有不同时间段的多个梯度,以便在保持频率依赖性的情况下,只需估计每个组织的单个参数即可。对具有四个组织的球形头部模型进行的数值研究研究了估算电导率值的可行性,并表明所提出的技术可以成功地重建这些电导率值。此外,还研究了材料模型的影响以及与梯度相关的谐波数,以及所提出的技术在存在噪声的情况下的性能。

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