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electrical impedance tomography

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https://www.readbyqxmd.com/read/29145478/electrical-impedance-tomography-amplitudes-of-cardiac-related-impedance-changes-in-the-lung-are-highly-position-dependent
#1
Michael Graf, Thomas Riedel
BACKGROUND: Electrical impedance tomography (EIT) is used on the thorax to measure impedance changes due to the presence of air and blood in the lung. This experimental study was performed to investigate the effect of posture on cardiac and respiratory related impedance changes. METHODS: EIT measurements were performed on 14 healthy subjects in left-, right lateral, prone, supine and upright positions. Simultaneously, tidal volume was recorded with an ultrasonic flowmeter...
2017: PloS One
https://www.readbyqxmd.com/read/29136345/regional-lung-function-testing-in-children-using-electrical-impedance-tomography
#2
Barbara Vogt, Sarah Löhr, Zhanqi Zhao, Christian Falkenberg, Tobias Ankermann, Norbert Weiler, Inéz Frerichs
OBJECTIVE: To evaluate regional lung function in lung-healthy children before and after exercise challenge using electrical impedance tomography (EIT). METHODS: Regional lung function was examined using EIT in 100 lung-healthy children (three age subgroups: 74-121, 122-155, 156-195 months) at baseline and 10 min after exercise. Global lung function was assessed by spirometry using Z-Scores of FEV1 , FVC, FEV1 /FVC, and FEF75 . The same lung function measures were determined in 912 EIT image pixels to enable the spatial and temporal ventilation distribution analysis...
November 14, 2017: Pediatric Pulmonology
https://www.readbyqxmd.com/read/29135866/importance-of-perimodiolar-electrode-position-for-psychoacoustic-discrimination-in-cochlear-implantation
#3
Angel Ramos Macias, Maria Teresa Perez Zaballos, Angel Ramos de Miguel, Javier Cervera Paz
HYPOTHESIS: Modiolar proximity of the cochlear implant electrodes and low impedance values have a positive effect on electrical pitch discrimination. BACKGROUND: The proximity of the cochlear electrode to the modiolar wall can determine changes in tissue and fluid environment. With the onset of soft-surgery techniques, the trauma caused during surgery has been reduced, minimizing fibrous growth. METHODS: Computed tomography-scan measurements of electrode-inner wall distance and psychoacoustic electrode discrimination tests were done...
December 2017: Otology & Neurotology
https://www.readbyqxmd.com/read/29099725/limitations-and-challenges-of-eit-based-monitoring-of-stroke-volume-and-pulmonary-artery-pressure
#4
Fabian Braun, Martin Proença, Mathieu Lemay, Mattia Bertschi, Andy Adler, Jean-Philippe Thiran, Josep Sola
<i>Objective</i>: Electrical impedance tomography (EIT) shows potential for radiation-free and non-invasive hemodynamic monitoring. However, many factors degrade the accuracy and repeatability of these measurements. Our goal is to estimate the impact of this variability on EIT-based monitoring of two important central hemodynamic parameters: stroke volume (SV) and pulmonary artery pressure (PAP). <i>Approach</i>: We performed simulations on a 4D (3D + t) bioimpedance model of a human volunteer to study the influence of four potential confounding factors (electrode belt displacement, electrode detachment, changes in hematocrit and lung air volume) on the performance of EIT-based SV and PAP estimation...
November 3, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/29060676/gamma-variate-modeling-of-indicator-dilution-curves-in-electrical-impedance-tomography
#5
Benjamin Hentze, Thomas Muders, Henning Luepschen, Steffen Leonhardt, Christian Putensen, Marian Walter
Electrical impedance tomography (EIT) is a non-invasive imaging technique, that can be used to monitor regional lung ventilation (V̇) in intensive care units (ICU) at bedside. This work introduces a method to extract regional lung perfusion (Q̇) from EIT image streams in order to quantify regional gas exchange in the lungs. EIT data from a single porcine animal trial, recorded during injection of a contrast agent (NaCl 10%) into a central venous catheter (CVC), are used for evaluation. Using semi-negative matrix factorization (Semi-NMF) a set of source signals is extracted from the data...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29060135/an-electrical-impedance-tomography-eit-multi-electrode-needle-probe-device-for-local-assessment-of-heterogeneous-tissue-impeditivity
#6
Davide Meroni, Camilla Carpano Maglioli, Dario Bovio, Francesco G Greco, Andrea Aliverti
Electrical Impedance Tomography (EIT) is an image reconstruction technique applied in medicine for the electrical imaging of living tissues. In literature there is the evidence that a large resistivity variation related to the differences of the human tissues exists. As a result of this interest for the electrical characterization of the biological samples, recently the attention is also focused on the identification and characterization of the human tissue, by studying the homogeneity of its structure. An 8 electrodes needle-probe device has been developed with the intent of identifying the structural inhomogeneities under the surface layers...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29059926/feasibility-study-of-imaging-fast-neural-activity-in-retinal-tissue-using-electrical-impedance-tomography
#7
Danyi Zhu, Xiunan Fang, Calvin Eiber, James Avery, David Holder, Alistair McEwan
Electrical Impedance Tomography has been recently applied to image fast neural activity in the somatosensory cerebral cortex. This non-invasive imaging modality has the unique advantage of high spatial-temporal resolution in millimeters over milliseconds. This work was designed to test an existing 32-channel EIT system, a modified UCL ScouseTom, and to discuss the feasibility of imaging neural activity in retinal tissue through computer simulation. The finite element method was used to model a retinal slice with a realistic conductivity-depth profile of the macaque eye...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29059883/monitoring-of-cardiac-output-and-lung-ventilation-by-electrical-impedance-tomography-in-a-porcine-model-of-acute-lung-injury
#8
Nadine Hochhausen, Henriette Dohmeier, Rolf Rossaint, Michael Czaplik
Adequate medical treatment of the Acute Respiratory Distress Syndrome is still challenging since patient-individual aspects have to be taken into account. Lung protective ventilation and hemodynamic stability have always been two of the most crucial aims of intensive care therapy. For both aspects, a continuous - preferably non-invasive - monitoring is desirable that is available at the bedside. Unfortunately, there is no technique clinically established yet, that provides both measurement of cardiac stroke volume and ventilation dynamics in real-time...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29059882/imaging-of-regional-air-distributions-in-porcine-lungs-using-high-performance-electrical-impedance-tomography-system
#9
G Y Jang, Y B Kim, H Wi, T I Oh, C R Chung, G Y Suh, E J Woo
Electrical impedance tomography (EIT) allows functional imaging of regional lung ventilation for real-time bedside monitoring of mechanically ventilated patients. Images showing time-changes of regional air distributions in the lungs can provide valuable diagnostic information for lung protective mechanical ventilation. This paper reports in vivo porcine imaging experiments of regional lung ventilation using a 16-channel parallel EIT system. Real-time time-difference chest images of 10 animals were reconstructed during mechanical ventilations with a temporal resolution of 50 frame/s...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29059834/electrical-properties-of-phantoms-for-mimicking-breast-tissue
#10
Vinicius G Sirtoli, Kaue Morcelles, Pedro Bertemes-Filho
In order to test and calibrate an EIT (Electrical Impedance Tomography) system, many researchers rely on phantoms mimicking breast tissues. These phantoms are usually made of saline solutions, agar and/or vegetables, allowing the user to set the conductivity of the material by changing the salt concentration. Due to that fact that the dispersion behavior in the vicinity of megahertz is fundamental to detect carcinoma, this work aims to propose a phantom composed by a mixture of agar and gelatin (emulating the normal tissue) and a piece of carrot (emulating the carcinoma)...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29059801/integration-of-piezo-capacitive-and-piezo-electric-nanoweb-based-pressure-sensors-for-imaging-of-static-and-dynamic-pressure-distribution
#11
Y J Jeong, T I Oh, E J Woo, K J Kim
Recently, highly flexible and soft pressure distribution imaging sensor is in great demand for tactile sensing, gait analysis, ubiquitous life-care based on activity recognition, and therapeutics. In this study, we integrate the piezo-capacitive and piezo-electric nanowebs with the conductive fabric sheets for detecting static and dynamic pressure distributions on a large sensing area. Electrical impedance tomography (EIT) and electric source imaging are applied for reconstructing pressure distribution images from measured current-voltage data on the boundary of the hybrid fabric sensor...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/29045567/individualized-positive-end-expiratory-pressure-in-obese-patients-during-general-anaesthesia-a-randomized-controlled-clinical-trial-using-electrical-impedance-tomography
#12
C Nestler, P Simon, D Petroff, S Hammermüller, D Kamrath, S Wolf, A Dietrich, L M Camilo, A Beda, A R Carvalho, A Giannella-Neto, A W Reske, H Wrigge, Jonathan Thompson
Background: General anaesthesia leads to atelectasis, reduced end-expiratory lung volume (EELV), and diminished arterial oxygenation in obese patients. We hypothesized that a combination of a recruitment manoeuvre (RM) and individualized positive end-expiratory pressure (PEEP) can avoid these effects. Methods: Patients with a BMI ≥35 kg m -2 undergoing elective laparoscopic surgery were randomly allocated to mechanical ventilation with a tidal volume of 8 ml kg -1 predicted body weight and (i) an RM followed by individualized PEEP titrated using electrical impedance tomography (PEEP IND ) or (ii) no RM and PEEP of 5 cm H 2 O (PEEP 5 )...
December 1, 2017: British Journal of Anaesthesia
https://www.readbyqxmd.com/read/29037075/optimal-distance-of-multi-plane-sensor-in-three-dimensional-electrical-impedance-tomography
#13
Zhenhua Hao, Shihong Yue, Benyuan Sun, Huaxiang Wang
Electrical impedance tomography (EIT) is a visual imaging technique for obtaining the conductivity and permittivity distributions in the domain of interest. As an advanced technique, EIT has the potential to be a valuable tool for continuously bedside monitoring of pulmonary function. The EIT applications in any three-dimensional (3 D) field are very limited to the 3 D effects, i.e. the distribution of electric field spreads far beyond the electrode plane. The 3 D effects can result in measurement errors and image distortion...
October 16, 2017: Computer Assisted Surgery (Abingdon, England)
https://www.readbyqxmd.com/read/29035213/a-fidelity-embedded-regularization-method-for-robust-electrical-impedance-tomography
#14
Kyounghun Lee, Eung Je Woo, Jin Keun Seo
Electrical impedance tomography (EIT) provides functional images of an electrical conductivity distribution inside the human body. Since the 1980s, many potential clinical applications have arisen using inexpensive portable EIT devices. EIT acquires multiple trans-impedance measurements across the body from an array of surface electrodes around a chosen imaging slice. The conductivity image reconstruction from the measured data is a fundamentally ill-posed inverse problem notoriously vulnerable to measurement noise and artifacts...
October 13, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/29019006/ventilation-inhomogeneity-in-obstructive-lung-diseases-measured-by-electrical-impedance-tomography-a-simulation-study
#15
B Schullcke, S Krueger-Ziolek, B Gong, R A Jörres, U Mueller-Lisse, K Moeller
Electrical impedance tomography (EIT) has mostly been used in the Intensive Care Unit (ICU) to monitor ventilation distribution but is also promising for the diagnosis in spontaneously breathing patients with obstructive lung diseases. Beside tomographic images, several numerical measures have been proposed to quantitatively assess the lung state. In this study two common measures, the 'Global Inhomogeneity Index' and the 'Coefficient of Variation' were compared regarding their capability to reflect the severity of lung obstruction...
October 10, 2017: Journal of Clinical Monitoring and Computing
https://www.readbyqxmd.com/read/28976087/noninvasive-diagnosis-in-dermatology
#16
Julia Welzel, Sandra Schuh
In addition to dermoscopy, there are other imaging and biophysical methods for the noninvasive diagnosis of skin lesions. Confocal laser microscopy allows for high-resolution imaging of the epidermis and upper dermis. It is particularly suitable in the differential diagnosis of melanocytic lesions. Optical coherence tomography (OCT) has a lower resolution compared to confocal laser microscopy but a greater depth of penetration. It is primarily used for imaging epithelial skin cancer, especially in the context of monitoring the effectiveness of nonsurgical therapies...
October 2017: Journal der Deutschen Dermatologischen Gesellschaft, Journal of the German Society of Dermatology: JDDG
https://www.readbyqxmd.com/read/28971420/applications-for-electrical-impedance-tomography-eit-and-electrical-properties-of-the-human-body
#17
Georgios Lymperopoulos, Panagiotis Lymperopoulos, Victoria Alikari, Chrisoula Dafogianni, Sofia Zyga, Nikoletta Margari
Electrical Impedance Tomography (EIT) is a promising application that displays changes in conductivity within a body. The basic principle of the method is the repeated measurement of surface voltages of a body, which are a result of rolling injection of known and small-volume sinusoidal AC current to the body through the electrodes attached to its surface. This method finds application in biomedicine, biology and geology. The objective of this paper is to present the applications of Electrical Impedance Tomography, along with the method's capabilities and limitations due to the electrical properties of the human body...
2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/28964244/design-of-current-source-for-multi-frequency-simultaneous-electrical-impedance-tomography
#18
Bing Han, Yanbin Xu, Feng Dong
Multi-frequency electrical impedance tomography has been evolving from the frequency-sweep approach to the multi-frequency simultaneous measurement technique which can reduce measuring time and will be increasingly attractive for time-varying biological applications. The accuracy and stability of the current source are the key factors determining the quality of the image reconstruction. This article presents a field programmable gate array-based current source for a multi-frequency simultaneous electrical impedance tomography system...
September 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28961282/physiologic-effects-of-alveolar-recruitment-and-inspiratory-pauses-during-moderately-high-frequency-ventilation-delivered-by-a-conventional-ventilator-in-a-severe-lung-injury-model
#19
Ricardo Luiz Cordioli, Eduardo Leite Vieira Costa, Luciano Cesar Pontes Azevedo, Susimeire Gomes, Marcelo Britto Passos Amato, Marcelo Park
BACKGROUND AND AIMS: To investigate whether performing alveolar recruitment or adding inspiratory pauses could promote physiologic benefits (VT) during moderately-high-frequency positive pressure ventilation (MHFPPV) delivered by a conventional ventilator in a porcine model of severe acute respiratory distress syndrome (ARDS). METHODS: Prospective experimental laboratory study with eight pigs. Induction of acute lung injury with sequential pulmonary lavages and injurious ventilation was initially performed...
2017: PloS One
https://www.readbyqxmd.com/read/28952939/a-parametric-level-set-method-for-electrical-impedance-tomography
#20
Dong Liu, Anil Kumar Khambampati, Jiangfeng Du
This paper presents an image reconstruction method based on parametric level set (PLS) method using electrical impedance tomography. The conductivity to be reconstructed was assumed to be piecewise constant and the geometry of the anomaly was represented by a shape-based PLS function, which we represent using Gaussian radial basis functions (GRBF). The representation of the PLS function significantly reduces the number of unknowns, and circumvents many difficulties that are associated with traditional level set (TLS) methods, such as regularization, re-initialization and use of signed distance function...
September 25, 2017: IEEE Transactions on Medical Imaging
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