First in vivo brain conductivity reconstructions using Helmholtz MR-Electrical Properties Tomography (MR-EPT) have been published. However, a large variation in the reconstructed conductivity values is reported and these values differ from ex vivo conductivity measurements. Given this lack of agreement, we performed an in vivo study on eight healthy subjects to provide reference in vivo brain conductivity values. MR-EPT reconstructions were performed at 3 T for eight healthy subjects. Mean conductivity and standard deviation values in the white matter, gray matter and cerebrospinal fluid (σ_WM, σ_GM, and σ_CSF) were computed for each subject before and after erosion of regions at tissue boundaries, which are affected by typical MR-EPT reconstruction errors. The obtained values were compared to the reported ex vivo literature values. To benchmark the accuracy of in vivo conductivity reconstructions, the same pipeline was applied to simulated data, which allow knowledge of ground truth conductivity. Provided sufficient boundary erosion, the in vivo σ_WM and σ_GM values obtained in this study agree for the first time with literature values measured ex vivo. This could not be verified for the CSF due to its limited spatial extension. Conductivity reconstructions from simulated data verified conductivity reconstructions from in vivo data and demonstrated the importance of discarding voxels at tissue boundaries. The presented σ_WM and σ_GM values can therefore be used for comparison in future studies employing different MR-EPT techniques.

首次发表了使用亥姆霍兹MR-电特性断层扫描（MR-EPT）进行的体内脑电导率重建。但是，据报道，重建的电导率值存在较大差异，这些值与离体电导率测量值不同。鉴于缺乏共识，我们对八名健康受试者进行了一项体内研究，以提供体内脑电导率参考值。MR-EPT重建在3 T下对8位健康受试者进行。平均数的导电性和白质的标准偏差值，灰质和脑脊液（σ _WM，σ _GM，σ _CSF）是针对每个受试对象在组织边界区域侵蚀之前和之后进行的计算，这些区域受典型MR-EPT重建误差的影响。将获得的值与报道的离体文献值进行比较。为了对体内电导率重建的准确性进行基准测试，将同一管道应用于模拟数据，从而可以了解地面真实电导率。提供了足够的边界侵蚀，体内σ _WM和σ _GM在这项研究中获得的值首次与离体测量的文献值一致。由于CSF的空间扩展有限，因此无法对其进行验证。来自模拟数据的电导率重建验证了来自体内数据的电导率重建，并证明了在组织边界处丢弃体素的重要性。所呈现的σ _WM和σ _GM因此值可以用于在采用不同MR-EPT技术未来的研究比较。