285 results about "Electrical impedance tomography" patented technology

An impedance model of tissue is useful for describing conductivity reconstruction in tissue. Techniques for determining and mapping conductivity distribution in tissue supply useful information of anatomical and physiological status in various medical applications. Electrical Impedance Tomography (EIT) techniques are highly suitable for analyzing conductivity distribution. Electrical characteristics of tissue include resistive elements and capacitive elements. EIT techniques involve passing a low frequency current through the body to monitor various anatomical and physiological characteristics. The system can interrogate at multiple frequencies to map impedance. Analytical techniques involve forward and inverse solutions to boundary value analysis to tissue characteristics.

Embodiments herein provide a non-invasive tracking system that accurately predicts the location of tumors, such as lung tumors, in real time, while allowing patients to breathe naturally. This is accomplished by using Electrical Impedance Tomography (EIT), in conjunction with spirometry, strain gauge and infrared sensors, and by using sophisticated patient-specific mathematical models that incorporate the dynamics of tumor motion. With the direction and speed of lung tumor movement successfully tracked, radiation may be effectively delivered to the lung tumor and not to the surrounding healthy tissue, thus increased radiation dosage may be directed to improving local tumor control without compromising functional parenchyma.

The invention relates to an electrode for biomedical measurements, in particular for measurements for electrical impedance tomography, which permits measurements with as little interference as possible. The electrodes comprise a contact plate, a line driver with a high-impedance signal input and low-impedance line output and a current source, with a current output and a reference point, whereby the contact plate is connected to the high-impedance signal input of the line driver and to the current output of the current source and the line driver and the current source are arranged in the vicinity of the contact plate.

The invention discloses a method for structural information fused electrical impedance tomography, which comprises the following steps: extracting internal structural information of an imaging target; converting the structural information into apriori information required by the electrical impedance tomography; performing the electrical impedance tomography by combining the obtained apriori information; and reconstructing structural information fused electrical impedance tomographic images to achieve the function. The method achieves the fused imaging of structural images and electrical impedance images, improves the accuracy of the electrical impedance images as functional images, improves the resolution of the images, and is helpful for a user to analyze the electrical impedance images at the same time.

Typical electrical impedance tomography (“EIT”) systems apply current to a body under test and measure the induced voltages on the surface and then through an inverse process, reconstruct an approximation to the electrical conductivity in the interior. The EIT system described herein employs a new approach to evaluating the interior electrical conductivity by using a virtual short that allows both current and voltages to be measured at various locations on the body under test. The architecture of this system is described, distinguishability of embedded conductive anomalies is evaluated, typical error sources associated with a virtual short measurement is discussed in the context of electrical impedance tomography, and a new imaging system is discussed.

The present teachings relate to the application of electrical impedance tomography (EIT) to demonstrate the multifunctionality of carbon nanocomposite thin films under various types of environmental stimuli. Carbon nanotube (CNT) thin films are fabricated by a layer-by-layer (LbL) technique or other techniques and mounted with electrodes along their boundaries. The response of the thin films to various stimuli determined by relying on electric current excitation and corresponding boundary potential measurements. The spatial conductivity variations are reconstructed based on a mathematical model for the EIT technique. Here, the ability of the EIT method to provide two-dimensional mapping of the conductivity of CNT thin films is validated by (1) electrically imaging intentional structural defects in the thin films and (2) mapping the film's response to various pH environments.

The present invention is a system for use in creating images of portions of human tissue inside the body by electrical impedance tomography. The system may comprise at least one flexible tube for insertion in the body in proximity to a targeted portion of human tissue in the body, an inflatable balloon removably attached to the distal end of the flexible tube, a first array of electrodes attached to the surface of the inflatable balloon for at least one of injecting current into the targeted portion of human tissue and receiving current that was injected into the targeted portion of human tissue, and a second array of electrodes for at least one of injecting current into the targeted portion of human tissue to the first array of electrodes and for receiving current from the first array of electrodes.

An electrode assembly for electrical impedance tomography comprising a plurality of different electrode modules, each containing a support strap made of a flexible material that presents a reduced longitudinal deformability and carrying a predetermined number of electrodes, each support strap being dimensioned to be seated and retained onto a respective extension portion of a body segment of a patient. Each electrode module presents the number of electrodes and a distance ‘De’ between each two consecutive electrodes predetermined as a function of a specific operational pattern to be obtained from each electrode module. The assembly can further comprise an electrical conducting cable having an end connected to a monitoring apparatus and a free end provided with a connector to be coupled to a respective electrode of an electrode module.

An EIT system includes a plurality of voltage sources for supplying a corresponding plurality of voltages to a corresponding number of other structures, voltage source calibration means for calibrating each voltage source, and switching means for individually connecting the calibration means to each voltage source in succession during a period when each other structure is in an inactive condition. Calibrating respective voltages and currents for each voltage source compensates for shunt impedance of each voltage source. A method for calibrating the system includes individually connecting the calibration means to each voltage source in succession during a period when each other structure is in an inactive condition for calibrating all of said voltage sources in the same way.

The invention discloses a device and a method capable of preferably reconstructing three-dimensional electrical impedance distribution in an object and improving electric field space distribution nonuniformity through obtaining object surface voltage information in particular relating to human organ tissues such as heads and breasts. Through the adoption of the scheme, voltage information can be obtained from both a horizontal section and a vertical section and images on the sections are respectively combined to form a space three-dimensional graphic; and voltages between the rest positions can be also obtained through exciting any contact point on the surface and then a plurality of combined measuring methods are achieved to realize multi-algorithm extension and improve image accuracy. The design mainly comprises 65 special electrodes distributed on a hemispherical surface; with a high-performance FPAG (Field Programmable Gate Array) as core, functions such as exciting source control, digital frequency synthesis, multiplex control, high speed phase-sensitive detection, fast Fourier transformation and measuring signal demodulation are integrated in a single chip; and a circuit design capable of self-adaptively adjusting output impedance of a detected object is achieved.

Transducer configurations and methods for transducer positioning in electrical impedance tomography are provided. A plurality of transducers for one electrical impedance tomography arrangement are configured for positioning proximate a surface of an object and spaced apart along the object, wherein the transducers are one or more conductive rings and have at least one non-conductive portion. The arrangement further includes one or more excitation drivers coupled to the plurality of transducers and configured to generate excitation signals for the plurality of transducers. The arrangement also includes one or more response detectors coupled to the plurality of transducers and configured to measure a response of the object at the plurality of transducers to the excitation applied by the plurality of transducers based on the excitation signals. The arrangement additionally includes a soft-field reconstruction module configured to reconstruct a property distribution based on the excitation signals and the measured response.

Method and apparatus for measuring a pulse transit time (PTT) value of a subject, comprising: measuring a first arterial pressure pulse arrival time (PAT) and measuring a second PAT value; calculating a PTT value from the difference between the first PAT value and the second PAT value; processing a sequence of electrical impedance tomography (EIT) images to identify at least one region of interest (ROI); and estimating at least one of the first and second PAT value from the variation of impedance value determined from said at least one ROI. The method allows for the non-invasive and continuous measurement of the PTT value and arterial blood pressures.

A method for creating multifunctional cementitious composites that provide load-bearing and self-sensing properties. The method involves dispersing conductive nanomaterials (e.g., multi-walled carbon nanotubes) into a polymer (e.g., latex) material from which a thin film is created and deposited (e.g., sprayed) onto aggregates, which after drying, can be incorporated with cementitious materials and desired liquids and cast, along with sufficient number of electrodes, into a form for curing. After curing, the resultant structure can be electrically tested through the electrodes, for structural characteristics, including determination of damage severity and location using back-calculation utilizing electrical resistance tomography (ERT), or electrical impedance tomography (EIT), to generate a spatial resistivity map (distribution).

A method is provided for taking electrical impedance tomography measurements using multiple electrodes located at selected positions external to a volume of a subject body. Multiple orthogonal or near-orthogonal signals are introduced simultaneously by way of selected different electrodes and resultant predetermined responses (if any) at receiving electrodes are recorded or determined. The signals are encoded using the technique of code division multiplexing and received signals at each receiving electrode are cross-correlated with original signals to determine the contribution of each original signal to a composite received signal. The invention also relates to apparatus suitable for use in applying a method.

Electrical tomography drive frequency selection systems and methods are disclosed. One aspect of the present invention pertains to a system for optimally selecting a drive frequency of an electrical tomography which comprises a sensor electrode stably associated with a tissue site within an internal organ of a subject for generating an induced signal based on a noise signal over a range of frequency bands, wherein an electrical field for the electrical tomography is turned off. In addition, the system comprises a noise processing module for isolating the induced signal for each frequency band over the range of frequency bands. Furthermore, the system comprises a frequency select module for selecting a drive frequency of the electrical field for the electrical tomography by comparing the induced signal for each frequency band over the range of frequency bands.

An electrode array, a system and a method for reconstructing the distribution of electrical properties within a multi-material object. One embodiment includes electrodes arranged along a three-dimensional helical path to provide one or more helical arrays and circuitry to measure signals for calculating a conductivity or admittivity distribution representative of the interior of the structure. Image data may be obtained which is representative of the multi-material region.

Electrical impedance myography (EIM) can be used for assessment and diagnosis of muscular disorders. EIM includes applying an electrical signal to a region of tissue and measuring a resulting signal. A characteristic of the region of tissue is determined based on the measurement. Performing EIM at different frequencies and modeling one or more impedance metrics as a function of frequency may provide impedance model parameters that can aid in the assessment and diagnosis. Devices are described that facilitate assessment and diagnosis using EIM.

The invention relates to an electrical tomography sparse reconstruction method based on Firm threshold iteration, wherein the method is used for electrical tomography of non-continuous medium. According to the method, an electrical tomography problem is seen for settling a linear ill-posed problem, and an objective function is determined. The reconstruction method comprises the steps of according to a tested field domain, acquiring a relative boundary measured value vector and a sensitivity matrix required for reconstruction; setting an initial parameter; performing acceleration pretreatment; according to a regularization parameter which is calculated in a previous cycle, namely a threshold value which is selected in threshold iterative calculation in this time, and performing threshold iterative calculation on a previous iteration result after acceleration processing; calculating the number of non-zero elements in a solution which is obtained in iteration in this time, and updating sparseness; determining whether iteration is finished; and performing imaging according to a gray value which is obtained through final solving. The electrical tomography sparse reconstruction method improves applicability and usability of an algorithm and furthermore expands application range of a sparse reconstruction method.

The invention refers to a method for the regional determination of the alveolar opening and alveolar closing of the lung depending on the respiration pressure, wherein according to the method of electrical impedance tomography, an impedance signal is measured in at least one lung zone depending on the respiration pressure. The alveolar opening or closing of a lung zone is determined, in particular to enable an improved artificial respiration.