PDF(Pubmed)
Abstract：
This work was inspired by the observation that a majority of MR-electrical properties tomography studies are based on direct comparisons with ex vivo measurements carried out on post-mortem samples in the 90\'s. As a result, the in vivo conductivity values obtained from MRI in the megahertz range in different types of tissues (brain, liver, tumors, muscles, etc.) found in the literature may not correspond to their ex vivo equivalent, which still serves as a reference for electromagnetic modelling. This study aims to pave the way for improving current databases since the definition of personalized electromagnetic models (e.g. for Specific Absorption Rate estimation) would benefit from better estimation. Seventeen healthy volunteers underwent MRI of both brain and thorax/abdomen using a three-dimensional ultrashort echo-time (UTE) sequence. We estimated conductivity (S/m) in several classes of macroscopic tissue using a customized reconstruction method from complex UTE images, and give general statistics for each of these regions (mean-median-standard deviation). These values are used to find possible correlations with biological parameters such as age, sex, body mass index and/or fat volume fraction, using linear regression analysis. In short, the collected in vivo values show significant deviations from the ex vivo values in conventional databases, and we show significant relationships with the latter parameters in certain organs for the first time, e.g. a decrease in brain conductivity with age.
摘要：
这项工作受到以下观察的启发：大多数MR电学特性断层扫描研究都是基于与90年代对死后样本进行的离体测量的直接比较。因此,在不同类型的组织(脑，肝脏,肿瘤，肌肉,等。)在文献中发现的可能不符合它们的离体等价物，这仍然是电磁建模的参考。这项研究旨在为改善当前数据库铺平道路，因为个性化电磁模型的定义（例如，用于比吸收率估计）将受益于更好的估计。17名健康志愿者使用三维超短回波时间（UTE）序列对大脑和胸/腹部进行了MRI。我们从复杂的UTE图像中使用定制的重建方法估计几类宏观组织的电导率（S/m），并给出每个区域的一般统计数据(均值-中位数-标准差)。这些值用于找到与生物参数（如年龄）的可能相关性，性别,体重指数和/或脂肪体积分数，使用线性回归分析。总之,收集的体内值显示出与常规数据库中的体外值的显着偏差，我们首次在某些器官中显示出与后者参数的显着关系，例如，随着年龄的增长，大脑电导率下降。
