Multinode Electrical Impedance Tomography (<i>mn</i>EIT) Throughout Whole-Body Electrical Muscle Stimulation (<i>wb</i>EMS)
Prima Asmara Sejati, Bo Sun, Panji Nursetia Darma, T. Shirai, Kosei Narita, Masahiro Takei
Abstract
Multi-node electrical impedance tomography ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mn</i> EIT) throughout whole-body electrical muscle stimulation ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">wb</i> EMS) has been proposed for the simultaneous imaging of muscle compartments response. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mn</i> EIT has two characteristics which are 1) network hardware for synchronized measurement in multi-node simultaneously and 2) nodal fast Fourier transform (FFT) for cancelling time-varying noise. By <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mn</i> EIT, the muscle compartments response in the upper arm and thigh of eight healthy subjects are imaged throughout <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">wb</i> EMS under four voltage intensity levels. According to the reconstructed images of conductivity distribution σ in prior training and throughout <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">wb</i> EMS, the conductivity distribution trend of the upper arm and thigh are boosted along with the rise of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">wb</i> EMS voltage intensity. As the hardware error evaluation, the normalized spatial-mean impedance error ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>f</i></sub> of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mn</i> EIT is relatively higher in the increase of frequency while the average error 〈ε〉 is 7. 521% respectively. Here our <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mn</i> EIT has the best result at ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>f</i></sub> <〈ε〉 which occurred at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> ≤ 2500 Hz that covers the frequency selection <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> = 500 Hz and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> = 1000 Hz to obtain the best visualization of conductivity distribution σ. Meanwhile, based on the Pearson correlation as the statistical evaluation, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mn</i> EIT has a relatively high accuracy value at the upper arm <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">arm</sub> =0.9391 and thigh <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">thigh</sub> =0.894.