Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States of America.
Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah, United States of America.
PLoS One. 2021 Oct 29;16(10):e0259071. doi: 10.1371/journal.pone.0259071. eCollection 2021.
Electrical impedance myography (EIM) using surface techniques has shown promise as a means of diagnosing and tracking disorders affecting muscle and assessing treatment efficacy. However, the relationship between such surface-obtained impedance values and pure muscle impedance values has not been established. Here we studied three groups of diseased and wild-type (WT) animals, including a Duchenne muscular dystrophy model (the D2-mdx mouse), an amyotrophic lateral sclerosis (ALS) model (the SOD1 G93A mouse), and a model of fat-related atrophy (the db/db diabetic obese mouse), performing hind limb measurements using a standard surface array and ex vivo measurements on freshly excised gastrocnemius muscle. A total of 101 animals (23 D2-mdx, 43 ALS mice, 12 db/db mice, and corresponding 30 WT mice) were studied with EIM across a frequency range of 8 kHz to 1 MHz. For both D2-mdx and ALS models, moderate strength correlations (Spearman rho values generally ranging from 0.3-0.7, depending on the impedance parameter (i.e., resistance, reactance and phase) were obtained. In these groups of animals, there was an offset in frequency with impedance values obtained at higher surface frequencies correlating more strongly to impedance values obtained at lower ex vivo frequencies. For the db/db model, correlations were comparatively weaker and strongest at very high and very low frequencies. When combining impedance data from all three disease models together, moderate correlations persisted (with maximal Spearman rho values of 0.45). These data support that surface EIM data reflect ex vivo muscle tissue EIM values to a moderate degree across several different diseases, with the highest correlations occurring in the 10-200 kHz frequency range. Understanding these relationships will prove useful for future applications of the technique of EIM in the assessment of neuromuscular disorders.
表面肌电阻抗（EIM）技术已被证明是一种有前途的诊断和跟踪肌肉疾病的方法，并可评估治疗效果。然而，这种表面获得的阻抗值与纯肌肉阻抗值之间的关系尚未建立。在这里，我们研究了三组患病和野生型（WT）动物，包括杜氏肌营养不良症模型（D2-mdx 小鼠）、肌萎缩侧索硬化症（ALS）模型（SOD1 G93A 小鼠）和脂肪相关萎缩模型（db/db 糖尿病肥胖小鼠），使用标准表面阵列进行后肢测量，并对新鲜切除的腓肠肌进行离体测量。共对 101 只动物（23 只 D2-mdx、43 只 ALS 小鼠、12 只 db/db 小鼠和相应的 30 只 WT 小鼠）进行了 EIM 研究，频率范围为 8 kHz 至 1 MHz。对于 D2-mdx 和 ALS 模型，均获得了中等强度的相关性（Spearman rho 值通常在 0.3-0.7 之间，取决于阻抗参数（即电阻、电抗和相位）。在这些动物组中，表面较高频率下获得的阻抗值与离体较低频率下获得的阻抗值之间存在频率偏移，相关性更强。对于 db/db 模型，相关性相对较弱，在非常高和非常低的频率下最强。当将所有三种疾病模型的阻抗数据结合在一起时，中度相关性仍然存在（最大 Spearman rho 值为 0.45）。这些数据表明，表面 EIM 数据在多个不同疾病中能够在一定程度上反映离体肌肉组织 EIM 值，最高相关性出现在 10-200 kHz 频率范围内。了解这些关系将有助于将来在评估神经肌肉疾病时应用 EIM 技术。
