G.P.118: Net muscle volumetry by MRI and bioelectrical impedance analysis for healthy volunteers; an observation study

Abstract

Muscle volume in patients with muscle disease is an index of disease progression and efficacy of the therapy. We had developed the net muscle volumetry using CT (nMV_CT) which is capable of evaluating net muscle volume for over several years. We developed the net muscle volumetry using Dixon MRI (nMV_MRI) whose results were closely correlated to nMV_CT. Here we report a new method of net muscle volume of extremities of healthy volunteers by bioelectrical impedance analysis (BIA), compared with those of Dixon MRI. We evaluated the impedance index at 50 kHz (ZI50), which was generally used for body composition analysis, and the nMV_MRI of six thighs of three healthy volunteers (aged 5–12). An impedance analyzer (BCA-100_CTanita Corp., Japan) and 10 mm wide stainless steel electrodes were used for measuring bioelectrical impedance. A Siemens 1.5T MR scanner was used for Dixon MRI. The impedance and nMV_MRI were measured at the 10 cm section of the middle part of the thigh. The ZI50 of the subjects’ thighs were calculated. The nMV_MRI of thighs were measured as 500–1200 cm 3 , and ZI50 was calculated as 2.75–4.88 cm 2 /Ω. These results were closely correlated with each other with Pearson’s correlation coefficient of 0.866 ( p = 0.026). We can estimate ZI50 of thigh which is closely correlated to nMV_MRI. We can evaluate ZI50 easily, noninvasively, and repeatedly, and we consider that this new method is suitable for the biomarker of the disease progression and therapies.