Ohmine Yuken, Morimoto Tadaoki, Kinouchi Yohsuke, Iritani Tadamitsu, Takeuchi Mieko, Haku Mari, Nishitani Hiromu
Department of Surgery, Awa Hospital Tokushima Prefectural Welfare Federation on Agricaltural Cooperative, Tokushima, Japan.
J Med Invest. 2004 Aug;51(3-4):218-25. doi: 10.2152/jmi.51.218.
The purposes of this study were to estimate the electrical conductivity of tissues by non-invasively measuring the electrical bio-impedance, to develop a new method for tissue diagnosis, i.e., electrical impedance tomography (EIT). Tissue models were first designed taking into consideration the distribution of the fat tissue, muscle and bone in the human forearm, and then the intra-tissue distributions of electrical potential and field, and the electrical impedance in the models was theoretically analyzed by the three-dimensional finite element method. The electrical impedance of both forearms was measured in healthy human subjects, and estimated the electrical conductivity of individual local tissues. The results of the analysis showed that the distributions of electrical potential and field were affected by the presence of fat tissue but not by the presence or absence of bone. In addition, as a result of calculation of the electrical resistance of the extracellular fluid (Re) in each model, it was found that the value of bio-impedance was influenced by the presence of fat tissue, and the value of bio-impedance was increased by the intervention of a fat layer. The electrical conductivity estimated by fitting the observed values to the values obtained by finite element analysis was 0.40 S/m and 0.15 S/m for male muscle and fat tissue, and 0.35 S/m and 0.11 S/m for female muscle and fat tissue, respectively. The sex difference in the slope of linear approximation in the estimation of electrical conductivity of the males and females was thought to be due to sex differences in the properties and structure of fat tissue. These results suggest that local tissues can be diagnosed differentially and electrically by percutaneous measurement of local bio-impedance and subsequent estimation of the electrical conductivity of each tissue.
本研究的目的是通过非侵入性测量生物电阻抗来估计组织的电导率，开发一种新的组织诊断方法，即电阻抗断层成像（EIT）。首先，考虑到人体前臂中脂肪组织、肌肉和骨骼的分布设计组织模型，然后用三维有限元方法对模型中组织内的电势和电场分布以及电阻抗进行理论分析。在健康人体受试者中测量了双侧前臂的电阻抗，并估计了各个局部组织的电导率。分析结果表明，电势和电场分布受脂肪组织存在的影响，但不受骨骼存在与否的影响。此外，通过计算每个模型中细胞外液的电阻（Re）发现，生物阻抗值受脂肪组织存在的影响，并且脂肪层的介入会使生物阻抗值增加。通过将观测值与有限元分析得到的值进行拟合估算出的男性肌肉和脂肪组织的电导率分别为0.40 S/m和0.15 S/m，女性肌肉和脂肪组织的电导率分别为0.35 S/m和0.11 S/m。男性和女性在电导率估计中线性近似斜率的性别差异被认为是由于脂肪组织的性质和结构存在性别差异。这些结果表明，通过经皮测量局部生物阻抗并随后估计每个组织的电导率，可以对局部组织进行差异电学诊断。
