Faculty Profiles - NAKAMURA Takao

Preparation of a hand-held electrode array for electrical impedance myography

佐藤宏樹, 楠原俊昌, 神野俊克, 花山耕三, 中村隆夫

日本生体医工学会大会プログラム・抄録集(Web) 60th 437 - 437 2021

Authorship：Last author Language：Japanese Publisher：Japanese Society for Medical and Biological Engineering

In this experiment, a handheld electrode with an arc-shaped electrode mounting surface was fabricated using a plastic splint material (Easyform, Sakai Medical, Japan). A tape electrode (Ag-AgCl, 10 mm 80 mm) was attached to the electrode mounting surface, which was 80 mm length (circular arc of R 66 mm) 130 mm width, in a four-electrode configuration. Impedance measurements were performed using SFB7 (ImpediMed, Australia). Impedance measurements were performed on the rectus femoris and vastus lateralis muscles of five adult males. Impedance parameter were calculated by arc optimization using the Cole-Cole model using 172 points of Resistance and Reactance with frequencies ranging from 10 kHz to 300 kHz. Their reproducibility was analyzed using the intra-class correlation coefficient and the Bland-Altman analysis was used to analyze the error. The results showed that the ICC(1, 1) of each muscle was greater than 0.9 and no systematic error of each parameter occurred.

DOI： 10.11239/jsmbe.Annual59.437

Relationship between electrodes and current reach distance in EMI using bioequivalent phantom

佐藤宏樹, 中村隆夫, 楠原俊昌, 花山耕三

日本生体医工学会大会プログラム・抄録集(Web) 59th 399 - 399 2020

Language：Japanese Publisher：Japanese Society for Medical and Biological Engineering

In this experiment, two agar phantoms (70 mm 180 mm) with electrical conductivity of 6.61 m/s (muscle) and 0.99 m/s (fat) were used to construct a two-layered model (10 mm fat layer) assuming biological tissues. As the distance D between the current electrodes (40-100 mm, 4 conditions), the potential electrodes were placed at the inner 10 mm of the current electrode. Z was measured under six conditions in which the phantom thickness x was varied from 10 mm to 60 mm at 10 mm intervals. Z for x at the distance D between the electrodes was approximated as the sum of the exponential functions and constants. X, where the estimated value of Z is 105% of this constant value, was defined as the distance to reach the current, L. As a result of this experiment, L showed a linear correlation with D.

DOI： 10.11239/jsmbe.Annual58.399

Damping pattern of lower-leg supporting force released at the beginning of pendulum-test

楠原俊昌, 中村隆夫, 道西博行, 軸屋和明

日本生体医工学会大会プログラム・抄録集(Web) 59th 396 - 396 2020

Language：Japanese Publisher：Japanese Society for Medical and Biological Engineering

In knee-joint angular acceleration waveforms measured for pendulum-test of seated subject, some measurement errors may be caused by lower-leg supporting force remained after its start (residual force). Authors had corrected them temporally by approximating its damping pattern with a straight line. In this panel, we derived a better damping pattern from residual force measured on the way of the pendulum test. The residual forces in each of two normal subjects were measured 5 times under 3 initial knee-joint angles by a load sensor attached to palm for the lower-leg supporting. Normalization of measured damping patterns showed that it could be approximated by a quadratic function -a₁ t²-a₂ t+1, where a₁, a₂ were constants, the values of which might differ every measurement. Building such quadratic function in the inverse simulator for estimating spasticity, it is expected to be able to correct the influence of the residual force.

DOI： 10.11239/jsmbe.Annual58.396

Influence of thigh fluctuation upon pendulum-test waveforms

道西博行, 楠原俊昌, 中村隆夫, 岡本卓爾

日本生体医工学会大会プログラム・抄録集(Web) 59th 395 - 395 2020

Language：Japanese Publisher：Japanese Society for Medical and Biological Engineering

Although pendulum-test is a simple and objective method to estimate spasticity by the use of the waveform of knee-joint pendulum motion, it isn't easy to unify lower-leg support situation at the beginning of its measurement without heavy burden on the subject. Large amount of fluctuation therefore exists in initial part of most waveform. We measured knee-joint angular velocity waveforms under the initial hip-joint positions of different angle as the first step to clarify its behavior. In each case, a damped oscillation was observed which constructed by 2~3 saw-tooth like spikes, and the higher the angle of the initial position was, the larger its amplitude became. Inverse simulation of the measured waveform showed that, the larger the initial angle of the hip-joint was, the larger the residual became. Present problem is to develop some way to be able to remove such an influence, reserving the present lower-leg support situation.

DOI： 10.11239/jsmbe.Annual58.395

Study of the skin electric impedance model applied the water content of stratum corneum

上原治, 中村隆夫, 楠原俊昌, 松崎健一, 山本尚武

日本生体医工学会大会プログラム・抄録集(Web) 59th 400 - 400 2020

Language：Japanese Publisher：Japanese Society for Medical and Biological Engineering

The deterioration of skin barrier function causes symptoms such as allergy as various chemical substances may enter human body. We think it is very useful to quantitatively evaluate the stratum corneum thickness and the water content of stratum corneum as the skin barrier function in domains such as dermatology, nursing science and the cosmetics development. We studied the new model regarded as the parallel model of the resistor and the capacitor applied the stratum corneum thickness of the skin stripped model measured the confocal laser scanning microscopy and the water content of stratum corneum of the skin stripped model measured the confocal raman microscopy. We found the stratum corneum thickness with the impedance has strong correlation with the stratum corneum thickness with the confocal laser scanning microscopy, and the water content of stratum corneum with the impedance has strong correlation with the stratum corneum thickness with the confocal raman microscopy.

DOI： 10.11239/jsmbe.Annual58.400

Correction of unstable lower-leg supporting force on pendulum-test by quadric curve approximation

中村隆夫, 楠原俊昌, 道西博行, 山本尚武

日本生体医工学会大会プログラム・抄録集(Web) 59th 397 - 397 2020

Authorship：Lead author,　Corresponding author Language：Japanese Publisher：Japanese Society for Medical and Biological Engineering

In pendulum-test of seated subjects, measured waveforms had frequently included much distortion due to the lower-leg supporting force remained after its release. The authors had tried to correct it by approximating the damping pattern of the force with a linear one. In this study, we used a more accurate damping pattern of quadratic curve in place of the linear pattern. The former pattern was derived from variation of lower-leg supporting pressure measured on the way of the pendulum-test. The results of inverse simulation to waveforms measured from two healthy subjects and two spastic patients showed that its accuracy was improved more highly than in the case of the linear pattern and there existed considerable difference between estimations of spasticity obtained under two patterns. A future work is to grope for possibility of practical use.

DOI： 10.11239/jsmbe.Annual58.397

Electrical Impedance Myographyにおける電極間距離と電流到達距離の関係性-下肢筋の測定に向けた基礎的研究-

佐藤宏樹, 中村隆夫, 楠原俊昌, 軸屋和明, 河島隆貴, 小原謙一, 國安勝司, 花山耕三

日本生体医工学会大会プログラム・抄録集(Web) 58th S190_2 - S190_2 2019

Language：Japanese Publisher：公益社団法人日本生体医工学会

Electrical Impedance Myography（EIM）は, 表面電極を用いた骨格筋の固有インピーダンス測定により, 筋線維の構造的完成度や疾患原性変化などの質的な評価指標となり得る可能性が示されている. しかし, 骨格筋は皮下脂肪などの非筋肉組織より深部に位置することから, 対象筋に応じた電極間距離の調整が必要である. 本研究は下肢筋の固有インピーダンス測定に向けた基礎的研究として, 深部筋群のEIMを想定した電極間距離と電流到達距離の関係性を調査した.本実験では, 容器に生理食塩水を入れ, 水面に設置した2つの表面電極（Ag-AgCl, 15 mm×10 mm）により, 生理食塩水のインピーダンスの大きさZをLCRメータ（4284A, Agilent）で測定した.水深xがある値以上となればZは一定値となり, 水深を浅くすると電流経路の狭くなることでZは増加するため,電極間距離D（50-190 mm, 6条件）に対して水深（4-60 mm）を 4 mm間隔で変化させてZを測定した. 電極間距離Dにおけるxに対するZを指数関数と定数との和として近似計算した. Zの推定値がこの定数値105％の値となるxを電流到達距離Lと定義した. 本実験の結果, Dが19 mmの場合, Lは31.6 mmとなった. さらに電極間距離Dと電流到達距離Lには直線的な相関関係を示した.

DOI： 10.11239/jsmbe.Annual57.S190_2

Development of impedance measuring device for evaluation of skin barrier function

UEHARA OSAMU, NAKAMURA TAKAO, KUSUHARA TOSHIMASA, MATSUZAKI KENICHI, YAMAMOTO YOSHITAKE

Transactions of Japanese Society for Medical and Biological Engineering 56 S404 - S404 2018

Language：Japanese Publisher：Japanese Society for Medical and Biological Engineering

The deterioration of skin barrier function causes symptoms such as allergy as various chemical substances may enter human body. It is very useful to quantitatively evaluate the state of the skin barrier in domains such as dermatology, nursing science and the cosmetics development. Therefore the authors developed an impedance measuring device for evaluation of skin barrier function. As the head of this device contacts the skin, the parameters, such as susceptance B and admittance Y in two kinds of frequencies, are measured in approximately five seconds. It calculates skin barrier index correlates the stratum corneum thickness. The correlation with these parameters and the stratum corneum thickness measured the confocal laser scanning microscopy, and the regression expressions for estimation of the stratum corneum thickness were examined. We found that the thickness of the stratum corneum using impedance is equivalent to the thickness of the stratum corneum by confocal laser scanning microscopy.

DOI： 10.11239/jsmbe.Annual56.S404

Influence of the femoral fluctuation at the beginning of pendulum-test upon the lower-leg motion

Kusuhara Toshimasa, Nakamura Takao, Michinishi Hiroyuki, Jikuya Kazuaki, Yamamoto Yoshitake, Okamoto Takuji

Transactions of Japanese Society for Medical and Biological Engineering 57th S188 - S188 2018

Language：Japanese Publisher：Japanese Society for Medical and Biological Engineering

At the beginning of the pendulum-test, some fluctuation is induced in the femur by its upward shifting with releasing of lower-leg. This study analyzes its influence upon lower-leg motion by simulations. The fluctuation is controlled by a viscoelastic element of the iliopsoas muscle including the sitting seat. Behavior of all over the leg is modeled as a double pendulum constructed based on the viscoelastic elements and an existing lower-leg sub-model. We analyzed the femoral motion and the lower-leg motion under the double pendulum model. It was seen from the results that a tiny and nonlinear fluctuation like that appeared in measured angular acceleration waveforms exists also in the simulated lower-leg ones, and that its amplitude increased with increases of the upward shifting or advance of spasticity. One of the urgent works is to investigate some way to remove the fluctuation from measured waveform.

DOI： 10.11239/jsmbe.Annual56.S188

Influence of releasing from lower-leg support upon waveform of lower-leg motion in pendulum-test

NAKAMURA TAKAO, KUSUHARA TOSHIMASA, MICHINISHI HIROYUKI, JIKUYA KAZUAKI, YAMAMOTO YOSHITAKE, OKAMOTO TAKUJI

Transactions of Japanese Society for Medical and Biological Engineering 57th S187 - S187 2018

Language：Japanese Publisher：Japanese Society for Medical and Biological Engineering

In order to simplify the procedure of its execution in our pendulum-test, an examiner had supported the lower-leg of the subject in a sitting situation manually until just before its start. The supporting force had however been apt to remain for a short time after its start. This study analyzed the influence of the residual supporting force on the lower-leg motion. It was assumed that the residual force decreased linearly with time. A simulator for the analysis was constructed by supplementing the function of the residual force to the existing one under such assumption. The influence on the lower-leg motion was investigated by comparing simulated waveforms with measured ones. Time when the force disappears was determined by means of reverse simulation of the measured waveform, so that both waveforms agreed as much as possible. As the results, the accuracy of the simulator increased dramatically.

DOI： 10.11239/jsmbe.Annual56.S187

Influence of femur-tibia contact point shifting in pendulum-test upon lower-leg motions.

MICHINISHI HIROYUKI, KUSUHARA TOSHIMASA, NAKAMURA TAKAO, JIKUYA KAZUAKI, YAMAMOTO YOSHITAKE, OKAMOTO TAKUJI

Transactions of Japanese Society for Medical and Biological Engineering 57th S189 - S189 2018

Language：Japanese Publisher：Japanese Society for Medical and Biological Engineering

It has been known from our experience that femur-tibia contact point shifting can occur inside the knee-joint in the pendulum-test by a tiny difference in lower-leg and return to the original position on the way of its execution. This study analyzes its influence on the lower-leg motions. Its shifting is expressed as an angle between the lower-leg and the straight line connecting the contact point with the knee-joint axis. The function of the return from the shifting is modeled by introducing imaginary viscoelastic elements, whose values are proportional to the magnitude of the angle. The lower-leg motion is simulated by the use of the existing pendulum-test model supplemented with the viscoelastic elements. It is shown from the results that, the larger the angle and/or the higher the spasticity of the subject is, the more the disturbance increases.

DOI： 10.11239/jsmbe.Annual56.S189