Yuken Ohmine, Tadaoki Morimoto, Yohsuke Kinouchi, Tadamitsu Iritani, Mieko Takeuchi, Mari Haku and Hiromu Nishitani : Basic study of new diagnostic modality according to non-invasive measurement of the electrical conductivity of tissues, The Journal of Medical Investigation : JMI, Vol.51, No.3,4, 218-225, 2004.
(要約)
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.
Mari Haku, Mieko Takeuchi, Tadaoki Morimoto, Shuji Yamano and Keiko Takebayashi : Relationship between mammary gland structures during pregnancy and breast-feeding, JNI : The Journal of Nursing Investigation, Vol.2, No.1, 16-20, 2004.
(要約)
Study Purpose Diagnostic indices for prediction of breast milk production and assessment of care necessary for mammary gland structure during the pregnancy period were investigated. Methods Development of mammary gland during the pregnancy period was examined via ultrasound methodology. Each subject underwent three measurements once per trimester. Quantity of post-partum breast milk production was also measured ; furthermore, the relationship between mammary gland image and production quantity was evaluated. Results and conclusion As previously reported, mammary gland reaches a certain level of development during the course of pregnancy. Four distinct types of developmental pattern were observed. Mammary gland exhibited remarkable development up to the 15th week of pregnancy in comparison with non-pregnant adult females in type 1. In type 2, mammary gland displayed significant development from the 16th to the 35th week of pregnancy. In types 3 and 4, mammary gland tissue development, which was apparent from 35 weeks, was characterized by gland thickness of > 20 mm and < 20 mm, respectively. Among these four types, type 1 mammary gland demonstrated the largest level of breast milk production. Therefore, we suggest that understanding with respect to mammary gland structure during pregnancy contributes toward individual support in breast-feeding following childbirth.
Xueli Zhao, Yohsuke Kinouchi, Emiko Yasuno, Dayong Gao, Tadamitsu Iritani, Tadaoki Morimoto and Mieko Takeuchi : A New Method for Noninvasive Measurement of Multilayer Tissue Conductivity and Structure Using Divided Electrodes, IEEE Transactions on Biomedical Engineering, Vol.51, No.2, 362-370, 2004.
(要約)
This paper outlines a new method for measuring multilayer tissue conductivity and structure by using divided electrodes, in which current electrodes are divided into several parts. Our purpose is to estimate the multilayer tissue structure and the conductivity distribution in a cross section of the local tissue by using bioresistance data measured noninvasively. The effect of the new method is assessed by computer simulations using a typical two-dimensional (2-D) model. In this paper, the conductivity distribution in the model is analyzed based on a finite difference method (FDM) and a steepest descent method (SDM). Simulation results show that the conductivity values of skin, fat, and muscle layers can be estimated with an error of less than 0.1%. When random noise at various levels is added to the measured resistance values, estimates of the conductivity values for skin, fat, and muscle layers are still reasonably precise: their root mean square errors are about 1.06%, 1.39%, and 1.61% for 10% noise. In a 2-D model, increasing the number of divided electrodes permits simultaneous estimates of tissue structure and conductivity distribution. Optimal configuration for divided electrodes is examined in terms of dividing pattern.
Xueli Zhao, Yohsuke Kinouchi, Emiko Yasuno, Dayong Gao, Tadamitsu Iritani, Tadaoki Morimoto and Mieko Takeuchi : A New Method for Non-Invasive Measurement of Multi-layer Tissue Conductivity and Structure Using Divided Electrodes, IEEE Transactions on Biomedical Engineering, Vol.1, No.11, 1-10, 2002.
6.
Xueli Zhao, Yohsuke Kinouchi, Tadamitsu Iritani, Tadaoki Morimoto and Mieko Takeuchi : Estimation of Multi-Layer Tissue Conductivities from Non-invasively Measured Bioresistances Using Divided Electrodes, IEICE Transactions on Information and Systems, Vol.E85-D, No.6, 1031-1038, 2002.
(要約)
To estimate inner multi-layer tissue conductivity distribution in a cross section of the local tissue by using bioresistance data measured noninvasively on the surface of the tissue, a measurement method using divided electrodes is proposed, where a current electrode is divided into several parts. The method is evaluated by computer simulations using a three-dimension (3D) model and two two-dimension (2D) models. In this paper, conductivity distributions of the simplified (2D) model are analyzed based on a combination of a finite difference method (FDM) and a steepest descent method (SDM). Simulation results show that conductivity values for skin, fat and muscle layers can be estimated with an error less than 0.1%. Even though different strength random noise is added to measured resistance values, the conductivities are estimated with reasonable precise, e.g., the average error is about 4.25% for 10% noise. The configuration of the divided electrodes are examined in terms of dividing pattern and the size of surrounding guard electrodes to confine and control the input currents from the divided electrodes within a cross sectional area in the tissue.
Yumi Kuwamura, Tadaoki Morimoto, Ayako Tamura, Takako Ichihara, Takako Minagawa, Kanako Katai, Mari Haku, Mieko Takeuchi and Toshiko Tada : Temperature effect of a disinfectant in operative field during surgery under local anesthesia, Nursing & Health Sciences, Vol.2, No.4, 205-210, 2000.
Yuuken Oomine, Tadaoki Morimoto, Yohsuke Kinouchi, Tadamitsu Iritani, Mieko Takeuchi and Yasumasa Monden : Noninvasive Measurement of the Electrical Bioimpedance of Breast Tumors, Anticancer Research, Vol.20, No.3B, 1941-1946, 2000.
(要約)
The purpose of this study was to evaluate the possibility of differential diagnosis of tumors, such as breast cancer, by measuring the mammary electrical bioimpedance via the skin surface noninvasively and by examining the relationship between the tissue structure of the breast and electrical bioimpedance. The mammary electrical bioimpedance was measured in 24 patients with breast cancer. Taking into account the measurement results and the distribution of the mammary glands and fatty tissue, a breast model with tumors was proposed. Based on this model, the distributions of the electric potential and electric field in the tissue were theoretically analyzed by the three-dimensional finite element method. In clinical cases, the Re values of the diseased breast were significantly larger than those of the contralateral healthy breast. In theoretical analysis based on the breast model, the Re value of mammary electrical bioimpedance varied due to the structure of the breast, that is, the ratio of fatty tissue to mammary gland and the presence of mammary tumors. The results of the measurement agreed with the theoretical analyses. These results suggest that differential diagnosis of breast tumors is possible by measuring the mammary electrical bioimpedance using noninvasive electrodes on the skin.
(キーワード)
Adipose Tissue / Breast / Breast Diseases / Breast Neoplasms / Computer Simulation / Diagnosis, Differential / Electric Impedance / Electrodiagnosis / Female / Galvanic Skin Response / Humans / Models, Theoretical
(文献検索サイトへのリンク)
● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 10928131
Emiko Yasuno, Xueli Zhao, Yohsuke Kinouchi, Tadaoki Morimoto, Mieko Takeuchi and Yuuken Oomine : Parameter Estimation of the Local Tissue Impedance by Using Divided Electrode for EIT, 2004 RISP International Workshop on Nonlinear Circuits and Signal Processing, 379-382, Honolulu, Mar. 2004.
2.
Hiroyuki Bando, Emiko Yasuno, Yohsuke Kinouchi, Tadamitsu Iritani, Tadaoki Morimoto and Mieko Takeuchi : A New Method for Estimating Bioimpedance Distribution in a Local Tissue Using Divided Electrodes - Towards Local EIT, Proceedings of World Congress on Medical Physics and Biomedical Engineering, Sydney, Australia, August 24-29, 2003, MO.TR1-38, Sydney, Aug. 2003.
3.
Kenji Izukura, Xueli Zhao, Yohsuke Kinouchi, Tadamitsu Iritani, Tadaoki Morimoto and Mieko Takeuchi : A New Method of Electrical Impedance Tomography for Conductivity Distribution in Multi-layer Local Tissue from Non-invasively Measured Bioresistances, international Congress on Biological and Medical Engineering Programme&Handbook, 132, Singapore, Dec. 2002.
4.
Yumi Komai, Emiko Yasuno, Yohsuke Kinouchi, Tadamitsu Iritani, Tadaoki Morimoto and Mieko Takeuchi : Theoretical Studies on Electrical Impedance Tomography Based on Equivalent Circuits for the Local Tissue by Use of a Divided Ilectrode, international Congress on Biological and Medical Engineering Programme&Handbook, 50, Singapore, Dec. 2002.
5.
Xueli Zhao, Yohsuke Kinouchi, Tadamitsu Iritani, Tadaoki Morimoto and Mieko Takeuchi : Estimation of Conductivity Distribution in the Local Tissue Using a Divided Electrode, Proceedings of The International Technical Conference on Circuits/Systems, Computers and Communications, Vol.2, 1262-1267, Tokushima, Jul. 2001.