Guidelines to electrode positioning for human and animal electrical impedance myography research

Abstract

The positioning of electrodes in electrical impedance myography (EIM) is critical for accurately assessing disease progression and effectiveness of treatment. In human and animal trials for neuromuscular disorders, inconsistent electrode positioning adds errors to the muscle impedance. Despite its importance, how the reproducibility of resistance and reactance, the two parameters that define EIM, are affected by changes in electrode positioning remains unknown. In this paper, we present a novel approach founded on biophysical principles to study the reproducibility of resistance and reactance to electrode misplacements. The analytical framework presented allows the user to quantify a priori the effect on the muscle resistance and reactance using only one parameter: the uncertainty placing the electrodes. We also provide quantitative data on the precision needed to position the electrodes and the minimum muscle length needed to achieve a pre-specified EIM reproducibility. The results reported here are confirmed with finite element model simulations and measurements on five healthy subjects. Ultimately, our data can serve as normative values to enhance the reliability of EIM as a biomarker and facilitate comparability of future human and animal studies.

Fatigue-Induced Cole Electrical Impedance Model Changes of Biceps Tissue Bioimpedance

“…It is important to note that electrode positioning has a significant impact on the measured electrical impedance of localized tissues [30] yet there is no widely adopted process to standardize electrode placement for localized bio-impedance measurements; though recent guidelines have been proposed [31]. A limitation of this work is that the use of only a single-electrode configuration on the study participants fails to provide the data necessary to evaluate the optimum configuration to detect changes in the localized tissues due to exercise and fatigue.…”

Sensitivity distribution simulations of surface electrode configurations for electrical impedance myography

“…Herein we have studied the changes in impedance through FEM simulations after intentionally varying only the subcutaneous fat thickness and surface electrode configuration. This is a major difference with respect to experimental studies, where changes in impedance could be originated by experimental errors [22][23][24][25][26][27] and other physiological factors beyond solely subcutaneous fat thickness. Importantly, the lack of standard measurement protocols across all previous experimental studies and knowledge of the in-vivo tissue dielectric properties makes it impossible to perform a direct comparison to the values reported here.…”

Non-invasive evaluation of muscle disease in the canine model of Duchenne muscular dystrophy by electrical impedance myography

“…The skin was cleaned and moistened with physiological saline. The electrode surface of the EIM device was positioned over the center of the bulk of the muscle on the skin as described in detail elsewhere [46]. Three consecutive multi-frequency impedance measurements were made on each muscle.…”