scholarly journals Decomposition of High-Frequency Electrical Conductivity into Extracellular and Intracellular Compartments based on Two-Compartment Model using Low-to-High Multi-b Diffusion MRI

2020 ◽  
Author(s):  
Mun Bae Lee ◽  
Hyung Joong Kim ◽  
Oh-In Kwon
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
High Frequency ◽  
Compartment Model ◽  
Biological Tissues ◽  
Extracellular Medium ◽  
Two Compartment Model ◽  
Random Decision Forests ◽  
Human Experiments ◽  
Micro Structures

Abstract Background: As an object's electrical passive property, the electrical conductivity is proportional to the mobility and concentration of charged carriers that reflect the brain micro-structures. The measured Mb-DWI data by controlling the degree of applied diffusion weights can quantify the apparent mobility of water molecules within biological tissues. Without any external electrical stimulation, magnetic resonance electrical properties tomography (MREPT) techniques have successfully recovered the conductivity distribution at a Larmor-frequency. Methods: This work provides a non-invasive method to decompose the high-frequency conductivity into the extracellular medium conductivity based on a two-compartment model using multi-b diffusion-weighted imaging (Mb-DWI). To separate the intra- and extracellular micro-structures from the recovered high-frequency conductivity, we include higher b-values DWI and apply the random decision forests to stably determine the micro-structural diffusion parameters. Results: To demonstrate the proposed method, we conducted human experiments by comparing the results of reconstructed conductivity of extracellular medium and the conductivity in the intra-neurite and intra-cell body. Human experiments verify that the proposed method can recover the extracellular electrical properties from the high-frequency conductivity using a routine protocol sequence of MRI scan. Conclusion: We have proposed a method to decompose the electrical properties in the extracellular, intra-neurite, and soma compartments from the high-frequency conductivity map, reconstructed by solving the electro-magnetic equation with measured B1 phase signals.

scholarly journals Decomposition of high-frequency electrical conductivity into extracellular and intracellular compartments based on two-compartment model using low-to-high multi-b diffusion MRI

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Mun Bae Lee ◽  
Hyung Joong Kim ◽  
Oh In Kwon
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
High Frequency ◽  
Compartment Model ◽  
Biological Tissues ◽  
Extracellular Medium ◽  
Two Compartment Model ◽  
Random Decision Forests ◽  
Human Experiments ◽  
Micro Structures

Abstract Background As an object’s electrical passive property, the electrical conductivity is proportional to the mobility and concentration of charged carriers that reflect the brain micro-structures. The measured multi-b diffusion-weighted imaging (Mb-DWI) data by controlling the degree of applied diffusion weights can quantify the apparent mobility of water molecules within biological tissues. Without any external electrical stimulation, magnetic resonance electrical properties tomography (MREPT) techniques have successfully recovered the conductivity distribution at a Larmor-frequency. Methods This work provides a non-invasive method to decompose the high-frequency conductivity into the extracellular medium conductivity based on a two-compartment model using Mb-DWI. To separate the intra- and extracellular micro-structures from the recovered high-frequency conductivity, we include higher b-values DWI and apply the random decision forests to stably determine the micro-structural diffusion parameters. Results To demonstrate the proposed method, we conducted phantom and human experiments by comparing the results of reconstructed conductivity of extracellular medium and the conductivity in the intra-neurite and intra-cell body. The phantom and human experiments verify that the proposed method can recover the extracellular electrical properties from the high-frequency conductivity using a routine protocol sequence of MRI scan. Conclusion We have proposed a method to decompose the electrical properties in the extracellular, intra-neurite, and soma compartments from the high-frequency conductivity map, reconstructed by solving the electro-magnetic equation with measured B1 phase signals.

scholarly journals A THREE-PHASE INDUCTIVE SENSOR FOR IN VIVO MEASUREMENT OF ELECTRICAL ANISOTROPY OF BIOLOGICAL TISSUES

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Yukio Kosugi ◽  
Tadashi Takemae ◽  
Hiroki Takeshima ◽  
Atsushi Kudo ◽  
Kazuyuki Kojima ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
High Frequency ◽  
Reference Signal ◽  
Biological Tissues ◽  
Electrical Anisotropy ◽  
Conductivity Anisotropy ◽  
In Vivo Measurement ◽  
Surgical Operations

Biological tissue will have anisotropy in electrical conductivity, due to the orientation of muscular fibers or neural axons as well as the distribution of large size blood vessels. Thus, the in vivo measurement of electrical conductivity anisotropy can be used to detect deep-seated vessels in large organs such as the liver during surgeries. For diagnostic applications, decrease of anisotropy may indicate the existence of cancer in anisotropic tissues such as the white matter of the brain or the mammary gland in the breast. In this paper, we will introduce a new tri-phase induction method to drive rotating high-frequency electrical current in the tissue for the measurement of electrical conductivity anisotropy. In the measurement, three electromagnets are symmetrically placed on the tissue surface and driven by high-frequency alternative currents of 0 kHz, modulated with 1 kHz 3-phase signals. In the center area of three magnets, magnetic fields are superimposed to produce a rotating induction current. This current produces electrical potentials among circularly arranged electrodes to be used to find the conductivity in each direction determined by the electrode pairs. To find the horizontal and vertical signal components, the measured potentials are amplified by a 2ch lock-in amplifier phase-locked with the 1 kHz reference signal. The superimposed current in the tissue was typically 45 micro Amperes when we applied 150 micro Tesla of magnetic field. We showed the validity of our method by conducting in vitro measurements with respect to artificially formed anisotropic materials and preliminary in vivo measurements on the pig’s liver. Compared to diffusion tensor MRI method, our anisotropy sensor is compact and advantageous for use during surgical operations because our method does not require strong magnetic field that may disturb ongoing surgical operations.

scholarly journals Gas distribution in a two-compartment model ventilated in high-frequency percussive and pressure-controlled modes

2010 ◽  
Vol 36 (12) ◽  
pp. 2125-2131 ◽  
Author(s):  
Umberto Lucangelo ◽  
Agostino Accardo ◽  
Alessandro Bernardi ◽  
Massimo Ferluga ◽  
Massimo Borelli ◽  
...  
Keyword(s):  
High Frequency ◽  
Compartment Model ◽  
Gas Distribution ◽  
Two Compartment Model ◽  
Pressure Controlled

Inclusion Compounds of Tetracyano Complexes and Their Electrical Properties

1994 ◽  
Vol 59 (11) ◽  
pp. 2436-2446 ◽  
Author(s):  
Mária Reháková ◽  
Anna Sopková ◽  
Vladimír Šály
Keyword(s):  
Electrical Conductivity ◽  
Chemical Composition ◽  
Electrical Properties ◽  
General Formula ◽  
Inclusion Compounds ◽  
High Frequency ◽  
Iodide Ions ◽  
Structure And Morphology ◽  
Composition Structure ◽  
Tetracyano Complexes

The presence of iodine and iodide ions in tetracyanonickelates inclusion compounds with the general formula Ni(B)mNi(CN)4 . n H2O (B = NH3 or ethylenediamine) changes the properties of these compounds. High frequency conductance measurements in the range of 10 - 105 Hz show that the products with ethylenediamine ligands have a higher electrical conductivity than those with NH3 ligands. The differences in the electrical properties between the compounds studied are mainly caused by chemical composition, structure and morphology.

Efflux du 36Cl et distribution du Cl dans le muscle papillaire du lapin, effet de l'ouabaïne

1981 ◽  
Vol 59 (8) ◽  
pp. 794-799
Author(s):  
Jean-Pierre Caillé
Keyword(s):  
Rate Constant ◽  
Papillary Muscle ◽  
Compartment Model ◽  
Rapid Rate ◽  
Extracellular Medium ◽  
Cellular Compartment ◽  
Rapid Exchange ◽  
Two Compartment Model ◽  
In Series

The 36Cl efflux "in vivo" was measured in the rabbit papillary muscle to determine the Cl distribution in the muscle and to evaluate the effect of ouabain on this parameter. The results obtained for the 36Cl efflux are analyzed using either a two-compartment model or a model including diffusion in the extracellular space in series with one compartment. The Cl exchange with 36Cl, *[Cl]i (intracellular Cl content which has participated in exchanges. [Formula: see text]) is computed from the exponential terms of the models. A time exposure of 40 and 80 min to the 36Cl-containing solution led to the same exchange Cl content: 20.5 and 23.9 mmol/kg cells. Addition of ouabain (10−6M) slightly increased the rate constant of the cellular compartment, but did not influence the *[Cl]i. In the presence of ouabain (10−6M), there was a significant increase in the efflux component with a rapid rate constant. These results can be interpreted as follows: the Cl intracellular concentration is not affected by ouabain; thus, the increase in total Cl content induced in the papillary muscle by ouabain is located in a compartment having a very rapid exchange velocity with the extracellular medium.[Journal translation]

The potential of fracture imaging using high‐frequency, single‐hole electromagnetic data

Geophysics ◽  
2002 ◽  
Vol 67 (4) ◽  
pp. 1087-1094 ◽  
Author(s):  
Soon Jee Seol ◽  
Jung Hee Suh ◽  
Yoonho Song ◽  
Hee Joon Kim ◽  
Ki Ha Lee
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
High Frequency ◽  
Least Squares Method ◽  
Thin Sheet ◽  
Integral Equation Method ◽  
Displacement Current ◽  
High Electrical Conductivity ◽  
Single Hole ◽  
Electrical Permittivity

This paper presents an inversion scheme for high‐frequency electromagnetic (EM) data from a single borehole for detection and characterization of fluid‐filled fractures. Water in the fracture zone may be characterized by its high electrical permittivity and, if saline, by high electrical conductivity. High electrical conductivity results in increased attenuation of EM fields, whereas high electrical permittivity reduces the phase velocity of propagating EM fields. Taking advantage of these effects, we use high‐frequency EM fields to detect and characterize fluid‐filled fractures. To demonstrate the feasibility of single‐hole EM imaging, we develop a three‐step inversion scheme to map a fluid‐filled fracture near the borehole and to evaluate its electrical conductivity and permittivity. We assume that a fluid‐filled fracture can be simulated by a conductive thin sheet. To test our inversion scheme, we generated synthetic data using the thin‐sheet integral equation method. A vertical magnetic dipole was used as a source, and the resultant magnetic fields were inverted using a nonlinear least‐squares method. First, the background conductivity and permittivity were obtained using vertical magnetic field data from below and above the transition frequency, at which conduction and displacement current magnitudes are equal. Next, using the phase difference between EM fields at two neighboring frequencies in the wave propagation realm, both the vertical and dipping sheets were successfully mapped using NMO and migration techniques. Electrical properties of the sheet were well resolved by subsequent inversion after having fixed the location of the sheet and host electrical properties. This study shows the potential of imaging the fracture using high‐frequency EM data obtained from single‐hole surveys.

scholarly journals Identification of Brain Damage after Seizures Using an MR-Based Electrical Conductivity Imaging Method

Diagnostics ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 569
Author(s):  
Sanga Kim ◽  
Bup Kyung Choi ◽  
Ji Ae Park ◽  
Hyung Joong Kim ◽  
Tong In Oh ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Magnetic Resonance ◽  
Electrical Properties ◽  
Brain Damage ◽  
High Frequency ◽  
Neuronal Cell ◽  
Imaging Method ◽  
Nissl Staining ◽  
Functional Changes ◽  
Conductivity Imaging

Previous imaging studies have shown the morphological malformation and the alterations of ionic mobility, water contents, electrical properties, or metabolites in seizure brains. Magnetic resonance electrical properties tomography (MREPT) is a recently developed technique for the measurement of electrical tissue properties with a high frequency that provides cellular information regardless of the cell membrane. In this study, we examined the possibility of MREPT as an applicable technique to detect seizure-induced functional changes in the brain of rats. Ultra-high field (9.4 T) magnetic resonance imaging (MRI) was performed, 2 h, 2 days, and 1 week after the injection of N-methyl-D-aspartate (NMDA; 75 mg/kg). The conductivity images were reconstructed from B1 phase images using a magnetic resonance conductivity imaging (MRCI) toolbox. The high-frequency conductivity was significantly decreased in the hippocampus among various brain regions of NMDA-treated rats. Nissl staining showed shrunken cell bodies and condensed cytoplasm potently at 2 h after NMDA treatment, and neuronal cell loss at all time points in the hippocampus. These results suggest that the reduced electrical conductivity may be associated with seizure-induced neuronal loss in the hippocampus. Magnetic resonance (MR)-based electrical conductivity imaging may be an applicable technique to non-invasively identify brain damage after a seizure.

Effect of Gamma Radiation on Structural, Optical and Electrical Properties of nanostructured CdHgTe Thin Films

2018 ◽  
Vol 1 (1) ◽  
pp. 26-31 ◽  
Author(s):  
B Babu ◽  
K Mohanraj ◽  
S Chandrasekar ◽  
N Senthil Kumar ◽  
B Mohanbabu
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Gamma Radiation ◽  
Glass Substrate ◽  
Gamma Ray ◽  
Optical And Electrical Properties ◽  
Deposition Technique ◽  
Polycrystalline Structure ◽  
Dc Electrical Conductivity

CdHgTe thin films were grown onto glass substrate via the Chemical bath deposition technique. XRD results indicate that a CdHgTe formed with a cubic polycrystalline structure. The crystallinity of CdHgTe thin films is gradually deteriorate with increasing the gamma irradiation. EDS spectrums confirms the presence of Cd, Hg and Te elements. DC electrical conductivity results depicted the conductivity of CdHgTe increase with increasing a gamma ray dosage

Effect of the structure of cellulose acetate membranes on their permeability, electrical conductivity and rejection

1990 ◽  
Vol 55 (12) ◽  
pp. 2933-2939 ◽  
Author(s):  
Hans-Hartmut Schwarz ◽  
Vlastimil Kůdela ◽  
Klaus Richau
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Cellulose Acetate ◽  
Reverse Osmosis ◽  
Water Flux ◽  
Cellulose Acetate Membrane ◽  
Structure Parameters ◽  
Dc Electrical Conductivity ◽  
Cellulose Acetate Membranes

Ultrafiltration cellulose acetate membrane can be transformed by annealing into reverse osmosis membranes (RO type). Annealing brings about changes in structural properties of the membranes, accompanied by changes in their permeability behaviour and electrical properties. Correlations between structure parameters and electrochemical properties are shown for the temperature range 20-90 °C. Relations have been derived which explain the role played by the dc electrical conductivity in the characterization of rejection ability of the membranes in the reverse osmosis, i.e. rRO = (1 + exp (A-B))-1, where exp A and exp B are statistically significant correlation functions of electrical conductivity and salt permeation, or of electrical conductivity and water flux through the membrane, respectively.

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