Evaluation of the effectiveness of electrical muscle stimulation on human calf muscles via frequency difference electrical impedance tomography

Abstract

Objectives. The human skeletal muscle responds immediately under electrical muscle stimulation (EMS), and there is an immediate physiological response in human skeletal muscle. Non-invasive quantitative analysis is at the heart of our understanding of the physiological significance of human muscle changes under EMS. Response muscle areas of human calf muscles under EMS have been detected by frequency difference electrical impedance tomography (fd-EIT). Approach. The experimental protocol consists of four parts: pre-training (pre), training (tra), post-training (post), and relaxation (relax) parts. The relaxation part has three relaxation conditions, which are massage relaxation (MR), cold pack relaxation (CR), and hot pack relaxation (HR). Main results. From the experimental results, conductivity distribution images σ p (p means protocol = pre, tra, post, or relax) are clearly reconstructed by fd-EIT as response muscle areas, which are called the M 1 response area (composed of gastrocnemius muscle) and the M 2 response area (composed of the tibialis anterior muscle, extensor digitorum longus muscle, and peroneus longus muscle). A paired samples t-test was conducted to elucidate the statistical significance of spatial-mean conductivities 〈σ p 〉 M1 and 〈σ p 〉 M2 in M 1 and M 2 with reference to the conventional extracellular water ratio β p by bioelectrical impedance analysis. Significance. From the t-test results, 〈σ p 〉 M1 and 〈σ p 〉 M2 have good correlation with β p . In the post-training part, 〈σ post 〉 and β post were significantly higher than in the pre-training part (n = 24, p < 0.001). The relax–pre difference ratios of spatial-mean conductivity Δ〈σ relax–pre 〉 and the relax–pre difference ratios of extracellular water ratio Δβ relax–pre in both MR and CR were lower; on the contrary, the Δ〈σ relax–pre 〉 and Δβ relax–pre in HR were significantly higher than those in post–pre difference ratios of spatial-mean conductivity Δ〈σ post–pre 〉 (n = 8, p < 0.05). The reason for the changes in 〈σ p 〉 M1 and 〈σ p 〉 M2 are caused by the changes in muscle extracellular volumes. In conclusion, fd-EIT satisfactorily evaluates the effectiveness of human calf muscles under EMS.

A high accuracy voltage approximation model based on object-oriented sensitivity matrix estimation (OO-SME model) in electrical impedance tomography

“…and used to optimize u(Δσ) by (2). In practice, an estimated conductivity σ o* of the object-field is used to calculate the estimated sensitivity matrix S o* , from which an estimated sensitivity matrix change ∆S * is calculated to replace ∆S.…”

“…As expressed by (2), u(Δσ) based on the OO-SME model contains three components, all of which have non-ignorable contributions to u(Δσ). Fig.…”

“…Electrical impedance tomography (EIT) is a promising visualization technique with low hardware cost, which reconstructs the conductivity change inside a domain from the voltage change on the boundary [ 1 ]. EIT has the potential to evaluate the effect of electrical muscle stimulation (EMS) on human muscles [ 2 , 3 ], where EMS is being expected to replace physical exercises of human body in the future. However, the EIT image has low accuracy [ 4 ], which restricts the accurate reconstruction of muscle compartments and the quantitative evaluation of EMS effect [ 5 , 6 ].…”

Gastric functional monitoring by gastric electrical impedance tomography (gEIT) suit with dual-step fuzzy clustering

“…In order to solve problem that there is no daily gastric function measurement method, because conventional techniques are not suitable: expensive, large, invasive, for monitoring gastric function, a recent development in electrical impedance tomography (EIT) 10 and mobile data acquisition systems 11 has opened the possibility of daily gastric morphological imaging. EIT has been successfully applied as an alternative bio-medical morphological imaging such as functional lung imaging 12 , muscle imaging 13 , and breast cancer imaging 14 , abdomen subcutaneous fat imaging 15 , and urinary bladder imaging 16 .…”

On-Line Multi-Frequency Electrical Resistance Tomography (mfERT) Device for Crystalline Phase Imaging in High-Temperature Molten Oxide

“…In order to perform the adequate imaging of the spatio-temporal distribution of oxide crystal in high-temperature molten oxide, electrical impedance tomography (EIT) [ 7 ] was proposed. Recently, EIT was improved as frequency difference EIT ( fd EIT) [ 8 ], also known as multi-frequency EIT ( mf EIT) [ 9 ], which has high potential as a measurement device for the on-line spatio-temporal distribution. The mf EIT can be simplified as multi-frequency electrical resistance tomography ( mf ERT) by focusing on the real part of the impedance for interpreting the distribution of the measured objects for reconstructing the images using a comprehensive image reconstruction algorithm.…”