Sadleir Rosalind, Grant Samuel, Zhang Sung Uk, Lee Byung Il, Pyo Hyun Chan, Oh Suk Hoon, Park Chunjae, Woo Eung Je, Lee Soo Yeol, Kwon Ohin, Seo Jin Keun
Department of Biomedical Engineering, University of Florida, Gainesville, USA.
Physiol Meas. 2005 Oct;26(5):875-84. doi: 10.1088/0967-3334/26/5/023. Epub 2005 Aug 8.
In magnetic resonance electrical impedance tomography (MREIT), we measure the induced magnetic flux density inside an object subject to an externally injected current. This magnetic flux density is contaminated with noise, which ultimately limits the quality of reconstructed conductivity and current density images. By analysing and experimentally verifying the amount of noise in images gathered from two MREIT systems, we found that a carefully designed MREIT study will be able to reduce noise levels below 0.25 and 0.05 nT at main magnetic field strengths of 3 and 11 T, respectively, at a voxel size of 3 x 3 x 3 mm(3). Further noise level reductions can be achieved by optimizing MREIT pulse sequences and using signal averaging. We suggest two different methods to estimate magnetic flux noise levels, and the results are compared to validate the experimental setup of an MREIT system.
在磁共振电阻抗断层成像（MREIT）中，我们测量在外部注入电流作用下物体内部感应的磁通密度。该磁通密度受到噪声污染，这最终限制了重构电导率和电流密度图像的质量。通过分析并实验验证从两个MREIT系统采集的图像中的噪声量，我们发现，精心设计的MREIT研究能够在体素大小为3×3×3 mm³时，分别在3 T和11 T的主磁场强度下将噪声水平降低至0.25 nT和0.05 nT以下。通过优化MREIT脉冲序列并使用信号平均可以进一步降低噪声水平。我们提出了两种不同的方法来估计磁通噪声水平，并比较结果以验证MREIT系统的实验设置。
