筋内脂肪の評価における多周波インピーダンス法の有用性 －骨格筋画像から算出するエコー強度を比較対象として－

抄録

In this study, we performed echo intensity obtained from ultrasonographic images was used as a reference for intramuscular fat mass to determine whether intramuscular fat can be estimated non-invasively using the bioelectrical impedance method. The subjects were 45 healthy male university students (mean age 20.2±1.4 years) of the athletic club. An ultrasound images were taken from vastus lateralis, and the echo intensity was calculated from the obtained image using image analysis software. The impedance corresponding to each of the 17 points from 4to 700 kHz were collected using a multi-frequency impedance measuring device. In addition, intracellular resistance and extracellular resistance were calculated using Cole-Cole distribution model. Pearson’s correlation coefficient was used for the relationship between echo intensity and impedance. As a result, when using a frequency of 50 kHz or more, we observed a moderate correlation (r=0.529 ~ 0.597, p<0.001) between an impedance of 2cm at the distance between the sensing (V) and current (I) electrodes and echo intensity at 2cm from the skin surface. A moderate correlation (r=0.551, p<0.001) was observed between the intracellular resistance at the V-I electrode spacing of 2cm and echo intensity at 2cm form the skin surface. However, there was only a weak correlation between extracellular resistance and echo intensity. This suggests that the impedance and intracellular resistance measured at a frequency of 50 kHz or higher and with a V-I electrode spacing of 2cm reflect intramuscular fat.