Detection of Invasive Ductal Carcinoma in Quadrant Breast Areas by Electrical Impedance Tomography Implemented with Gaussian relaxation-time Distribution (EIT-GRTD).

Invasive ductal carcinoma (IDC) in breast specimens has been detected in the quadrant breast area: (I) upper outer, (II) upper inner, (III) lower inner, and (IV) lower outer areas by electrical impedance tomography implemented with Gaussian relaxation time distribution (EIT-GRTD). The EIT-GRTD consists of two steps which are 1) the optimum frequencyfoptselection and 2) the time constant enhancement of breast imaging reconstruction.foptis characterized by a peak in the majority measurement pair of the relaxation time distribution function γ, which indicates the presence of IDC. γ represents the inverse of conductivity and indicates the response of breast tissues to electrical currents across varying frequencies based on the Voigt circuit model. The EIT-GRTD is quantitatively evaluated by multi-physics simulations using a hemisphere container of mimic breast, consisting of IDC and adipose tissues as normal breast tissue under one condition with known IDC in quadrant breast area II. The simulation results show that EIT-GRTD is able to detect the IDC in four layers atfopt=30,170 Hz. EIT-GRTD is applied in the real breast by employed six mastectomy specimens from IDC patients. The placement of the mastectomy specimens in a hemisphere container is an important factor in the success of quadrant breast area reconstruction. In order to perform the evaluation, EIT-GRTD reconstruction images are compared to the CT scan images. The experimental results demonstrate that EIS-GRTD exhibits proficiency in the detection of the IDC in quadrant breast areas while compared qualitatively to CT scan images.

Non-invasive hERG channel screening based on electrical impedance tomography and extracellular voltage activation (EIT-EVA).

hERG channel screening has been achieved based on electrical impedance tomography and extracellular voltage activation (EIT-EVA) to improve the non-invasive aspect of drug discovery. EIT-EVA screens hERG channels by considering the change in extracellular ion concentration which modifies the extracellular resistance in cell suspension. The rate of ion passing in cell suspension is calculated from the extracellular resistance Rex, which is obtained from the EIT measurement at a frequency of 500 kHz. In the experiment, non-invasive screening is applied by a novel integrated EIT-EVA printed circuit board (PCB) sensor to human embryonic kidney (HEK) 293 cells transfected with the human ether-a-go-go-related gene (hERG) ion channel, while the E-4031 antiarrhythmic drug is used for hERG channel inhibition. The extracellular resistance Rex of the HEK 293 cells suspension is measured by EIT as the hERG channels are activated by EVA over time. The Rex is reconstructed into extracellular conductivity distribution change Δσ to reflect the extracellular K+ ion concentration change Δc resulting from the activated hERG channel. Δc is increased rapidly during the hERG channel non-inhibition state while Δc is increased slower with increasing drug concentration cd. In order to evaluate the EIT-EVA system, the inhibitory ratio index (IR) was calculated based on the rate of Δc over time. Half-maximal inhibitory concentration (IC50) of 2.7 nM is obtained from the cd and IR dose-response relationship. The IR from EIT-EVA is compared with the results from the patch-clamp method, which gives R2 of 0.85. In conclusion, EIT-EVA is successfully applied to non-invasive hERG channel screening.

Great Toe Tip Reconstruction after Severe COVID-19 Using Hemi-pulp V-Y Advancement Flap: A Case Report.

"COVID toe," one of the extrapulmonary disorders of coronavirus disease 2019 (COVID-19), may result in toe necrosis. In this case, we successfully reconstructed a severe COVID-19-induced defect in the great toe by using an innervated hemi-pulp V-Y advancement flap. A 48-year-old woman was diagnosed with fulminant myocarditis due to COVID-19 and received intensive care. Even after the acute phase, a skin defect measuring 10 mm × 7 mm was noted, exposing the underlying bone on her right great toe tip. Because of ulceration, she was unable to start walking training. To continue rehabilitation, we reconstructed it with the innerved hemi-pulp V-Y advancement flap. The pain improved quickly, and rehabilitation was resumed. During the 6-month follow-up period, no cosmetic or functional complications were observed. Plantar pressure measurements demonstrated favorable loading on the great toe, and it was a favorable outcome in walking function. This flap is a valuable option as one of the innervated flaps for toe-end necrosis with preserved blood flow, which helps in implementing prompt gait rehabilitation.

Drug selection pressure and fitness cost for artemether-resistant Plasmodium berghei ANKA parasites in vivo.

BACKGROUND: The clinical use of artemisinin-based combination therapies is threatened by increasing failure rates due to the emergence and spread of multiple drug resistance genes in most human Plasmodium strains. The aim of this study was to generate artemether-resistant (AMR) parasites from Plasmodium berghei ANKA (AMS), and determine their fitness cost. METHODS: Artemether resistance was generated by increasing drug pressure doses gradually for 9 months. Effective doses (ED50 and ED90) were determined using the 4-day suppressive test, and the indices of resistance (I) at 50% and 90% (I50 and I90) were determined using the ratio of either ED50 or ED90 of AMR to AMS, respectively. The stability of the AMR parasites was evaluated by: five drug-free passages (5DFPs), 3 months of cryopreservation (CP), and drug-free serial passages (DFSPs) for 4 months. Analysis of variance was used to compare differences in growth rates between AMR and AMS with 95% confidence intervals. RESULTS: ED50 and ED90 of AMS were 0.61 and 3.43 mg/kg/day respectively. I50 and I90 after 20 cycles of artemether selection pressure were 19.67 and 21.45, respectively; 5DFP values were 39.16 and 15.27, respectively; 3-month CP values were 29.36 and 10.79, respectively; and DFSP values were 31.34 and 12.29, respectively. The mean parasitaemia value of AMR (24.70% ± 3.60) relative to AMS (37.66% ± 3.68) at Day 7 post infection after DFSPs revealed a fitness cost of 34.41%. CONCLUSION: A moderately stable AMRP. berghei line was generated. Known and unknown mutations may be involved in modulating artemether resistance, and therefore molecular investigations are recommended.

Metal Particle Detection by Integration of a Generative Adversarial Network and Electrical Impedance Tomography (GAN-EIT) for a Wet-Type Gravity Vibration Separator.

The minor copper (Cu) particles among major aluminum (Al) particles have been detected by means of an integration of a generative adversarial network and electrical impedance tomography (GAN-EIT) for a wet-type gravity vibration separator (WGS). This study solves the problem of blurred EIT reconstructed images by proposing a GAN-EIT integration system for Cu detection in WGS. GAN-EIT produces two types of images of various Cu positions among major Al particles, which are (1) the photo-based GAN-EIT images, where blurred EIT reconstructed images are enhanced by GAN based on a full set of photo images, and (2) the simulation-based GAN-EIT images. The proposed metal particle detection by GAN-EIT is applied in experiments under static conditions to investigate the performance of the metal detection method under single-layer conditions with the variation of the position of Cu particles. As a quantitative result, the images of detected Cu by GAN-EIT ψÌ¿GAN in different positions have higher accuracy as compared to σ*EIT. In the region of interest (ROI) covered by the developed linear sensor, GAN-EIT successfully reduces the Cu detection error of conventional EIT by 40% while maintaining a minimum signal-to-noise ratio (SNR) of 60 [dB]. In conclusion, GAN-EIT is capable of improving the detailed features of the reconstructed images to visualize the detected Cu effectively.

A noise-controlling method by hybrid current-stimulation and voltage-measurement for electrical impedance tomography (HCSVM-EIT).

Image reconstruction in electrical impedance tomography (EIT) is a typical ill-posed inverse problem, from which the stability of conductivity reconstruction affects the reliability of physiological parameters evaluation. In order to improve the stability, the effect of boundary voltage noise on conductivity reconstruction should be controlled. A noise-controlling method based on hybrid current-stimulation and voltage-measurement for EIT (HCSVM-EIT) is proposed for stable conductivity reconstruction. In HCSVM-EIT, the boundary voltage is measured by one current-stimulation and voltage-measurement pattern (high-SNRpattern) with a higher signal-to-noise ratio (SNR); the sensitivity matrix is calculated by another current-stimulation and voltage-measurement pattern (low-condpattern) with a lower condition number; the boundary voltage is then transformed from thehigh-SNRpattern into thelow-condpattern by multiplying by an optimized transformation matrix for image reconstruction. The stability of conductivity reconstruction is improved by combining the advantages of thehigh-SNRpattern for boundary voltage measurement and thelow-condpattern for sensitivity matrix calculation. The simulation results show that the HCSVM-EIT increases the correlation coefficient (CC) of conductivity reconstruction. The experiment results show that theCCof conductivity reconstruction of the human lower limb is increased from 0.3424 to 0.5580 by 62.97% compared to the quasi-adjacent pattern, and from 0.4942 to 0.5580 by 12.91% compared to the adjacent pattern. In conclusion, the stable conductivity reconstruction with higherCCin HCSVM-EIT improves the reliability of physiological parameters evaluation for disease detection.

Skin layer classification by feedforward neural network in bioelectrical impedance spectroscopy.

Conductivity change in skin layers has been classified by source indicator ok (k=1: Stratum corneum, k=2: Epidermis, k=3: Dermis, k=4: Fat, and k=5: Stratum corneum + Epidermis) trained from feedforward neural network (FNN) in bioelectrical impedance spectroscopy (BIS). In BIS studies, treating the skin as a bulk, limits the differentiation of conductivity changes in individual skin layers, however skin layer classification using FNN shows promise in accurately categorizing skin layers, which is essential for predicting source indicators ok and initiating skin dielectric characteristics diagnosis. The ok is trained by three main conceptual points which are (i) implementing FNN for predicting k in conductivity change, (ii) profiling four impedance inputs αξ consisting of magnitude input α|z|, phase angle input αθ, resistance input αR, and reactance input αx for filtering nonessential input, and (iii) selecting low and high frequency pair (frlh) by distribution of relaxation time (DRT) for eliminating parasitic noise effect. The training data set of FNN is generated to obtain the αξ ∈ R10×17×10 by 10,200 cases by simulation under configuration and measurement parameters. The trained skin layer classification is validated through experiments with porcine skin under various sodium chloride (NaCl) solutions CNaCl = {15, 20, 25, 30, 35}[mM] in the dermis layer. FNN successfully classified conductivity change in the dermis layer from experiment with accuracy of 90.6% for the bipolar set-up at f6lh=10 &100 [kHz] and with the same accuracy for the tetrapolar at f8lh=35 &100 [kHz]. The measurement noise and systematic error in the experimental results are minimized by the proposed method using the feature extraction based on αξ at frlh.

Physiological-induced conductive response evaluation in specific muscle compartments under hybrid of electrical muscle stimulation and voluntary resistance training by electrical impedance tomography.

Objective: The physiological-induced conductive response has been visualised for evaluation in specific muscle compartments under hybrid (hybridEMS) of electrical muscle stimulation (EMS) and voluntary resistance training (VRT) by electrical impedance tomography (EIT). Methods: In the experiments, tendency of conductivity distribution images σ over time was clearly detected for three specific muscle compartments, which are called AM 1 compartment composed of biceps brachii muscle, AM 2 compartment composed of triceps brachii muscle, and AM 3 compartment composed of brachialis muscle, under three training modalities. Results: From the experimental results, the tendency of physiological-induced conductive response are increased in all three training modalities with increasing training time. Correspondingly, the spatial-mean conductivity <σ>AM1,AM2,AM3 increased with the conductance value G and extracellular water ratio ß of right arm by bio-impedance analysis (BIA) method. In addition, hybridEMS has the greatest effect on physiological-induced conductive response in AM 1, AM 2, and AM 3. Under hybridEMS, the spatial-mean conductivity increased from <σ pre > AM1 = 0.154 to <σ 23mins > AM1 = 0.810 in AM 1 muscle compartment (n = 8, p < 0.001); <σ pre > AM2 = 0.040 to <σ 23mins > AM2 = 0.254 in AM 2 muscle compartment (n = 8, p < 0.05); <σ pre > AM3 = 0.078 to <σ 23mins > AM3 = 0.497 in AM 3 muscle compartment (n = 8, p < 0.05). Conclusion: The paired-samples t-test results of <σ>AM1,AM2,AM3 under all three training modalities suggest hybridEMS has the most efficient elicitation on physiological induced conductive response compared to VRT and EMS. The effect of EMS on deep muscle compartment (AM 3) is slower compared to VRT and hybridEMS, with a significant difference after 15 min of training.

Free and bound sodium identification by skin dielectric properties separation algorithm of bioelectrical impedance spectroscopy (spa-BIS) in human skin model.

Free and bound sodium in human skin models have been identified by two proposals: skin's phantom fabrication and skin's dielectric properties separation algorithm of bioelectrical impedance spectroscopy (spa-BIS). Thespa-BIS consist of conductivity-permittivity separation, contact impedance compensation, and a correlation score algorithm based on the vessel with a bipolar electrode. The skin phantom fabrication comprises a recipe combination with temperature-controlled protocol and sodium molarity calculation. In experiments, the human skin models are created to mimic the electrical properties of skin under1MHzwith several different sodium molarities. Based on five types of human skin models with five samples of each group, the free sodium type conductivity and concentration resultsR2=0.9903-following a linear trendline of concentration change in skin tissues theorems with the fRequency range from1kHzto1MHz,while the bound sodium type resultsR2=0.9061-.Thespa-BIS compensate7-16Ωof vessel contact impedance. The dielectric properties of each type have been extracted with less than 10% of the average standard deviation, which is considered an accurate identification method of dermis dielectric properties. The algorithm successfully identifies sodium type: free sodium has a negative, and bound sodium has a positive correlation score trend. As an additional discussion, the different time-dependent effects, the different water content, and different agar content analyses have been provided in this study. As a robust analysis method, thespa-BIS has a prominent performance to replace a23Na-MRI in terms of free and bound sodium identification.

Sodium concentration imaging in dermis layer by square-wave open electrical impedance tomography (SW-oEIT) with spatial voltage thresholding (SVT).

In this study, sodium concentration in the dermis layer is imaged by the square wave open electrical impedance tomography (SW-oEIT) with spatial voltage thresholding (SVT). The SW-oEIT with SVT consists of three steps which are (1) voltage measurement, (2) spatial voltage thresholding, and (3) sodium concentration imaging. In the 1st step, the root mean square voltagevis calculated based on the measured voltagevunder the square wave currentIthrough the planar electrodes on the skin domain Ω. In the 2nd step, them-th measured voltagevis converted to a compensated voltagev*based on the voltage electrodes distancedvand threshold distancedΓin order to highlight the region of interest of the dermis layerΩd.In the 3rd step, sodium concentration is imaged by the Gauss-Newton reconstruction method. The SW-oEIT with SVT was applied to multi-layer skin simulation andex-vivoexperiments under various dermis sodium concentrationscin the range of 5-50 mM. As an image evaluation result, the spatial mean conductivity distributionσ*inΩdis successfully determined as increasingcon both simulations and experiments. The relationship between〈σ*〉andcwas evaluated by the determination coefficientR2and the normalized sensitivity〈S〉.The optimizeddΓwith the highest evaluation values ofR2=0.84 and〈S〉=0.83 is under the condition ofdΓ= 2 mm. Based on the signal evaluation, the SW-oEIT with SVT has a 15.32% higher correlation coefficientCCcompared to the conventionaloEIT based on sinewave injection.

Antimalarial activity assay of artesunate-3-chloro-4(4-chlorophenoxy) aniline in vitro and in mice models.

The global spread of multi-drug resistant P. falciparum, P. vivax, and P. malariae strains and absence of long-term effective vaccine makes chemotherapy the mainstay of malaria control strategies in endemic settings. The Mossman's assay and the Organization for Economic Co-operation and Development (OECD), 2001 guideline 423, were used to determine the cytotoxicity and acute oral toxicity of a novel hybrid drug, artesunate-3-Chloro-4(4-chlorophenoxy) aniline (ATSA), in vitro and in vivo, respectively. A modified Desjardins method was used to screen for antiplasmodial activity using P. falciparum (3D7 and W2) strains in vitro. The Peter's 4-day suppressive tests (4DTs) was used to evaluate the in vivo antimalaria activity using P. berghei ANKA strain, lumefantrine resistant (LuR), and piperaquine resistant (PQR) P. berghei lines. In silico prediction of absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiles was assayed using PreADMET online prediction tool. The reference drug in all experiments was artesunate (ATS). Statistical significance between ATSA's activities in treated and control mice was evaluated by one-way analysis of variance (ANOVA). Results show that inhibitory concentrations-50 (IC50) of ATSA is 11.47 ± 1.3 (3D7) and 1.45 ± 0.26 (W2) against 4.66 ± 0.93 (3D7) and 0.60 ± 0.15 (W2) ng/ml of ATS with a selective index of 2180.91(3D7) and a therapeutic index (TI) of > 71). No mortalities were observed in acute oral toxicity assays and mean weight differences for test and controls were statistically insignificant (P > 0.05). The in vivo activity of ATSA was above 40% with effective dosage-50 (ED50) of 4.211, 2.601, and 3.875 mg/kg body weight against P. berghei ANKA, LuR, and PQR lines, respectively. The difference between treated and control mice was statistically significant (P < 0.05). ATSA has high intestinal absorption (HIA) > 95% and has medium human ether-a-go-go related gene (hERG) K+ channel inhibition risks. Preclinical and clinical studies on ATSA are recommended to evaluate its value in developing novel drugs for future management of multi-drug resistant malaria parasites.

Non-invasive imaging of ion concentration distribution around cell spheroids by electrical impedance tomographic sensor printed on circuit board under temporal compensation by ion transport impedance model.

A non-invasive imaging called as PCB-EIT imaging has been proposed in order to image spatio-temporal ion concentration distribution around cell spheroids in 0.1 s of temporal resolution by a newly developed electrical impedance tomographic sensor printed on circuit board (PCB-EIT sensor). To realize the high temporal resolution in PCB-EIT imaging, the temporal compensation by the ion transport impedance model interpolating the extracted resistance of extracellular solution Rex obtained from the Cole-Cole equation is employed. To confirm the performance of PCB-EIT imaging, the ion concentration distribution around three cell spheroid types (GFP type (GFPT), Histone type (HT) and wild type (WT)) which are electrically different due to green fluorescent protein expressed in cytoplasm and nucleus of MRC-5. As a result, spatio-temporal ion concentration distributions due to ion transport from cell spheroid are successfully reconstructed by PCB-EIT imaging. The images by PCB-EIT imaging are validated with those by fluorescence ratio imaging within the distribution error εdis of 0.046 ± 0.0038 in maximum. For an evaluation of the ion diffusivity Dm of each cell spheroid type by the mass transfer simulation based on Fick's law, Dm of GFPT shows the highest value among the three cell types in the earlier time range from 4 s, while Dm of HT shows the highest one in the time range from 15 s, which indicates that PCB-EIT imaging is able to evaluate the ion transport characteristics of each cell type.

Simultaneous electrical online estimation of changes in blood hematocrit and temperature in cardiopulmonary bypass.

Two equations have been developed from multi-frequency measurements of blood impedance Zb for a simultaneous electrical online estimation of changes in blood hematocrit ΔH [%] and temperatures ΔT [K] in cardiopulmonary bypass (CPB). Zb of fixed blood volumes at varying H and T were measured by an impedance analyzer and changes in blood conductivity σb and relative permittivity εb computed. Correlation analysis were based on changes in σb with H or T at f = 1 MHz while H and T equations were developed by correlating changes in εb with H and T at dual frequencies of f = 1 MHz and f = 10 MHz which best capture blood plasma Zp and red blood cell cytoplasm Zcyt impedances respectively. Results show high correlations between σb and H (R2 = 0.987) or σb and T (R2 = 0.9959) indicating dependence of the electrical parameters of blood on its H and T. Based on computed εb, changes in blood hematocrit ΔH and temperature ΔT at a given time t are estimated as ΔH(t) = 1.7298Δεb (f = 1 MHz) - 1.0669Δεb (f = 10 MHz) and ΔT(t) = -2.186Δεb (f = 1 MHz) + 2.13Δεb (f = 10 MHz). When applied to a CPB during a canine mitral valve plasty, ΔH and ΔT had correlations of R2 = 0.9992 and R2 = 0.966 against H and T respectively as measured by conventional devices.

Study of transmembrane ion transport under tonicity imbalance using a combination of low frequency-electrical impedance spectroscopy (LF-EIS) and improved ion transport model.

Transmembrane ion transport under tonicity imbalance has been investigated using a combination of low frequency-electrical impedance spectroscopy (LF-EIS) and improved ion transport model, by considering the cell diameterd[m] and the initial intracellular ion concentrationcin[mM] as a function of tonicity expressed by sucrose concentrationcs[mM]. The transmembrane ion transport is influenced by extracellular tonicity conditions, leading to a facilitation/inhibition of ion passage through the cell membrane. The transmembrane transport coefficientP[m s-1], which represents the ability of transmembrane ion transport, is calculated by the extracellular ion concentrations obtained by improved ion transport model and LF-EIS measurement.Pis calculated as 4.11 × 10-6and 3.44 × 10-6m s-1atcsof 10 and 30 mM representing hypotonic condition, 2.44 × 10-6m s-1atcsof 50 mM representing isotonic condition, and 3.68 × 10-6, 5.16 × 10-6, 9.51 × 10-6, and 14.89 × 10-6m s-1atcsof 75, 100, 125 and 150 mM representing hypertonic condition. The LF-EIS results indicate that the transmembrane ion transport is promoted under hypertonic and hypotonic conditions compared to isotonic condition. To verify the LF-EIS results, fluorescence intensityF[-] of extracellular potassium ions is observed to obtain the temporal distribution of average potassium ion concentration within the region of 3.6µm from cell membrane interfacecROI[mM]. The slopes of ∆cROI/cROI1to timetare 0.0003, 0.0002, and 0.0006 under hypotonic, isotonic, and hypertonic conditions, wherecROI1denotes initialcROI, which shows the same tendency with LF-EIS result that is verified by the potassium ion fluorescence observation.

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

An on-line multi-frequency electrical resistance tomography (mfERT) device with a melt-resistive sensor and noise reduction hardware has been proposed for crystalline phase imaging in high-temperature molten oxide. The melt-resistive sensor consists of eight electrodes made of platinum-rhodium (Pt-20mass%Rh) alloy covered by non-conductive aluminum oxide (Al2O3) to prevent an electrical short. The noise reduction hardware has been designed by two approaches: (1) total harmonic distortion (THD) for the robust multiplexer, and (2) a current injection frequency pair: low fL and high fH, for thermal noise compensation. THD is determined by a percentage evaluation of k-th harmonic distortions of ZnO at f=0.1~10,000 Hz. The fL and fH are determined by the thermal noise behavior estimation at different temperatures. At  f <100 Hz, the THD percentage is relatively high and fluctuates; otherwise, THD dramatically declines, nearly reaching zero. At the determined fL≥ 10,000 Hz and fH≈ 1,000,000 Hz, thermal noise is significantly compensated. The on-line mfERT was tested in the experiments of a non-conductive Al2O3 rod dipped into conductive molten zinc-borate (60ZnO-40B2O3) at 1000~1200 °C. As a result, the on-line mfERT is able to reconstruct the Al2O3 rod inclusion images in the high-temperature fields with low error, ςfL, T = 5.99%, at 1000 °C, and an average error ⟨ςfL⟩ = 9.2%.

A High Accuracy Voltage Approximation Model Based on Object-oriented Sensitivity Matrix Estimation (OO-SME Model) in Electrical Impedance Tomography.

The image reconstruction in electrical impedance tomography (EIT) has low accuracy due to the approximation error between the measured voltage change and the approximated voltage change, from which the object cannot be accurately reconstructed and quantitatively evaluated. A voltage approximation model based on object-oriented sensitivity matrix estimation (OO-SME model) is proposed to reconstruct the image with high accuracy. In the OO-SME model, a sensitivity matrix of the object-field is estimated, and the sensitivity matrix change from the background-field to the object-field is estimated to optimize the approximated voltage change, from which the approximation error is eliminated to improve the reconstruction accuracy. Against the existing linear and nonlinear models, the approximation error in the OO-SME model is eliminated, thus an image with higher accuracy is reconstructed. The simulation shows that the OO-SME model reconstructs a more accurate image than the existing models for quantitative evaluation. The relative accuracy (RA) of reconstructed conductivity is increased up to 83.98% on average. The experiment of lean meat mass evaluation shows that the RA of lean meat mass is increased from 7.70% with the linear model to 54.60% with the OO-SME model. It is concluded that the OO-SME model reconstructs a more accurate image to evaluate the object quantitatively than the existing models.

Electrical-tomographic imaging of physiological-induced conductive response in calf muscle compartments during voltage intensity change of electrical muscle stimulation (vic-EMS).

Objectives. The electrical-tomographic imaging has been achieved for exploring differential tendency of physiological-induced conductive response in calf muscle compartments during voltage intensity change of electrical muscle stimulation (vic-EMS).Approach. In the experiments, the differential tendency of conductivity distribution imagesσduringvic-EMS were clearly imaged as three responsive muscle compartments, which are calledM1compartment composed of gastrocnemius muscle,M2compartment composed of tibialis anterior, extensor digitorum longus, and peroneus longus muscles, andM3compartment composed of soleus muscle.Main results. The differential tendency of spatial-mean conductivity 〈σ〉M1is the same as the differential tendency of venous blood flow velocityvbland blood lactate concentrationCblduringvic-EMS by the increased tendency of spatial-mean conductivity difference Δ〈σ〉M1, venous blood flow velocity difference Δvbland blood lactate concentration difference ΔCbl. The 〈σ〉M1is increased with the increase of voltage intensity from 〈σpre〉M1 = 0.142 [-] to 〈σl14 ã€‰ M1 = 0.442 [-] (pre: pre-training,l14: voltage level duringvic-EMSl = 14) by Δ〈σl14-pre〉M1 = 204.2% (n = 16,p < 0.01). Correspondingly, thevblandCblare increased with the increase of voltage intensity by Δvbll14-pre= 1480.5% (n = 16,p < 0.01) and ΔCbll14-pre= 230.1% (n = 16,p < 0.01) respectively.Significance: The reason for the differential tendency of increase in <σ>M1suggests an increase in muscle extracellular volumes duringvic-EMS due to the co-effect of venous blood flow velocity and blood lactate metabolism. Based on the conductivity second-order difference images∂2σM1φ∂φ2φand spatial-mean conductivity second-order difference∂2σM1φ∂φ2φ,optimum voltage intensityφOVIis discussed among sixteen volunteer subjects, which increased with a thicker subcutaneous fat layer.

In-vivoviscoelastic properties estimation in subcutaneous adipose tissue by integration of poroviscoelastic-mass transport model (pve-MTM) into wearable electrical impedance tomography (w-EIT).

In-vivoviscoelastic properties have been estimated in human subcutaneous adipose tissue (SAT) by integration of poroviscoelastic-mass transport model (pve-MTM) into wearable electrical impedance tomography (w-EIT) under the influence of external compressive pressure-P.Thepve-MTM predicts the ion concentration distributioncmod(t)by coupling the poroviscoelastic and mass transport model to describe the hydrodynamics, rheology, and transport phenomena inside SAT. Thew-EIT measures the time-difference conductivity distribution∆γ(t)in SAT resulted from the ion transport. Based on the integration, the two viscoelastic properties which are viscoelastic shear modulus of SATGvand relaxation time of SATτvare estimated by applying an iterative curve-fitting between the normalized average ion concentration distributioncˆmod(t)predicted frompve-MTM and the experimental normalized average ion concentration distributioncˆexp(t)derived fromw-EIT. Thein-vivoexperiments were conducted by applying external compressive pressure-Pon human calf boundary to induce interstitial fluid flow and ion movement in SAT. As a result, the value ofGvwas range from 4.9-6.3 kPa and the value ofτvwas range from 27.50-38.5 s with the value of average goodness-of-fit curve fittingR2 > 0.76. These values ofGvandτvwere compared to the human and animal tissue from the literature in order to verify this method. The results frompve-MTM provide evidence thatGvandτvplay a role in the predicted value ofcˆmod.

Quantitative Evaluation of Burn Injuries Based on Electrical Impedance Spectroscopy of Blood with a Seven-Parameter Equivalent Circuit.

A quantitative and rapid burn injury detection method has been proposed based on the electrical impedance spectroscopy (EIS) of blood with a seven-parameter equivalent circuit. The degree of burn injury is estimated from the electrical impedance characteristics of blood with different volume proportions of red blood cells (RBCs) and heated red blood cells (HRBCs). A quantitative relationship between the volume portion HHCT of HRBCs and the electrical impedance characteristics of blood has been demonstrated. A seven -parameter equivalent circuit is employed to quantify the relationship from the perspective of electricity. Additionally, the traditional Hanai equation has been modified to verify the experimental results. Results show that the imaginary part of impedance ZImt under the characteristic frequency (fc) has a linear relationship with HHCT which could be described by ZImt = -2.56HHCT - 2.01 with a correlation coefficient of 0.96. Moreover, the relationship between the plasma resistance Rp and HHCT is obtained as Rp = -7.2HHCT + 3.91 with a correlation coefficient of 0.96 from the seven -parameter equivalent circuit. This study shows the feasibility of EIS in the quantitative detection of burn injury by the quantitative parameters ZImt and Rp, which might be meaningful for the follow-up clinical treatment for burn injury.

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

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 imagesσp(pmeans protocol = pre,tra,post,or relax) are clearly reconstructed byfd-EIT as response muscle areas, which are called theM1response area (composed of gastrocnemius muscle) and theM2response area (composed of the tibialis anterior muscle, extensor digitorum longus muscle, and peroneus longus muscle). A paired samplest-test was conducted to elucidate the statistical significance of spatial-mean conductivities 〈σp〉M1and 〈σp〉M2inM1andM2with reference to the conventional extracellular water ratioßpby bioelectrical impedance analysis. Significance. From thet-test results, 〈σp〉M1and〈σp〉M2have good correlation withßp. In the post-training part, 〈σpost〉 andßpostwere significantly higher than in the pre-training part (n = 24,p < 0.001). The relax-pre difference ratios of spatial-mean conductivity Δ〈σrelax-pre〉 and the relax-pre difference ratios of extracellular water ratio Δßrelax-prein both MR and CR were lower; on the contrary, the Δ〈σrelax-pre〉 and Δßrelax-prein HR were significantly higher than those in post-pre difference ratios of spatial-mean conductivity Δ〈σpost-pre〉 (n = 8,p < 0.05). The reason for the changes in 〈σp〉M1and 〈σp〉M2are caused by the changes in muscle extracellular volumes. In conclusion,fd-EIT satisfactorily evaluates the effectiveness of human calf muscles under EMS.