Relationships between in vivo surface and ex vivo electrical impedance myography measurements in three different neuromuscular disorder mouse models

Abstract

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.

Surface Electrical Impedance Myography Detects Skeletal Muscle Atrophy in Aged Wildtype Zebrafish and Aged gpr27 Knockout Zebrafish

“…In fact, the data from the very lowest frequencies obtained are impressively artifact-free. The strong correlation to needle data across much of the frequency range supports this and follows what was previously reported in mice ex vivo data [58]. Indeed, the needle measurement taken immediately after a surface measurement was taken showed how surface EIM correlated with homologous needle EIM parameters, especially at lower frequencies (Figure 2).…”

Assessment of Low Back Pain in Helicopter Pilots Using Electrical Bio-Impedance Technique: A Feasibility Study

“…The bioimpedance measurement system consists of a Solartron 1260 impedance analyzer and a Solartron 1294 interface (Solartron Analytical, Farnborough, United Kingdom), which can operate at the frequency range from 10 Hz to 1 MHz with the accuracy of better than 0.01%. In this study, the current of 1 mA at 50 kHz was applied because the characteristic frequency of impedance property of muscle tissue was around 50 kHz ( Bartels et al, 2015 ; Pandeya et al, 2021 ). In order to reduce the effect of electrode-skin contact impedance, the four electrode strategy was adopted ( Yang et al, 2016 , 2017b ).…”

“…Considering that the electrode-skin contact impedance was much larger than the tissues impedance at low frequencies (below 1 kHz) (Rosell et al, 1988;Yang et al, 2017a), their measurement results included not only the tissue impedance between measuring electrodes, but also the electrode-skin contact impedance. To effectively eliminate the influence of electrode-skin contact impedance on the measurement results, we adopted the four-electrode approach to perform impedance measurement in this study (Bartels et al, 2015;Pandeya et al, 2021). The difference of lumbar muscle impedance for different LBP scales could be associated with the physiological structure of muscle tissue.…”