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electrical impedance tomography

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https://www.readbyqxmd.com/read/29770490/functional-magnetic-resonance-electrical-impedance-tomography-fmreit-sensitivity-analysis-using-an-active-bidomain-finite-element-model-of-neural-tissue
#1
Rosalind J Sadleir, Fanrui Fu, Munish Chauhan
PURPOSE: A direct method of imaging neural activity was simulated to determine typical signal sizes. METHODS: An active bidomain finite-element model was used to estimate approximate perturbations in MR phase data as a result of neural tissue activity, and when an external MR electrical impedance tomography imaging current was added to the region containing neural current sources. RESULTS: Modeling-predicted, activity-related conductivity changes should produce measurable differential phase signals in practical MR electrical impedance tomography experiments conducted at moderate resolution at noise levels typical of high field systems...
May 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29761349/intracochlear-administration-of-steroids-with-a-catheter-during-human-cochlear-implantation-a-safety-and-feasibility-study
#2
Nils K Prenzler, Rolf Salcher, Max Timm, Lutz Gaertner, Thomas Lenarz, Athanasia Warnecke
Suppression of foreign body reaction, improvement of electrode-nerve interaction, and preservation of residual hearing are essential research topics in cochlear implantation. Intracochlear pharmaco- or cell-based therapies can open new horizons in this field. Local drug delivery strategies are desirable as higher local concentrations of agents can be realized and side effects can be minimized compared to systemic administrations. When administered locally at accessible, basal parts of the cochlea, drugs reach apical regions later and in much lower concentrations due to poor diffusion patterns in cochlear fluids...
May 14, 2018: Drug Delivery and Translational Research
https://www.readbyqxmd.com/read/29753106/feasibility-of-imaging-evoked-activity-throughout-the-rat-brain-using-electrical-impedance-tomography
#3
Mayo Faulkner, Sana Hannan, Kirill Aristovich, James Avery, David Holder
Electrical Impedance Tomography (EIT) is an emerging technique which has been used to image evoked activity during whisker displacement in the cortex of an anaesthetised rat with a spatiotemporal resolution of 200 μm and 2 ms. The aim of this work was to extend EIT to image not only from the cortex but also from deeper structures active in somatosensory processing, specifically the ventral posterolateral (VPL) nucleus of the thalamus. The direct response in the cortex and VPL following 2 Hz forepaw stimulation were quantified using a 57-channel epicortical electrode array and a 16-channel depth electrode...
May 9, 2018: NeuroImage
https://www.readbyqxmd.com/read/29726838/estimating-regions-of-air-trapping-from-electrical-impedance-tomography-data
#4
Jennifer L Mueller, Peter A Muller, Michelle Mellenthin, Rashmi Murthy, Michael Capps, Melody Alsaker, Robin Deterding, Scott D Sagel, Emily DeBoer
OBJECTIVE: Electrical impedance tomography (EIT) has been shown as a viable non-invasive, bedside imaging modality to monitor lung function.This paper introduces a method for identifying regions of air trapping from EIT data collected during tidal breathing and breath-holding maneuvers. APPROACH: Ventilation-perfusion index maps are computed from dynamic EIT images. These maps are then used to identify regions of air trapping in the area of the lung as regions that are poorly ventilated but well perfused throughout the breathing and cardiac cycles...
May 4, 2018: Physiological Measurement
https://www.readbyqxmd.com/read/29708892/continuous-negative-abdominal-pressure-reduces-ventilator-induced-lung-injury-in-a-porcine-model
#5
Takeshi Yoshida, Doreen Engelberts, Gail Otulakowski, Bhushan Katira, Martin Post, Niall D Ferguson, Laurent Brochard, Marcelo B P Amato, Brian P Kavanagh
BACKGROUND: In supine patients with acute respiratory distress syndrome, the lung typically partitions into regions of dorsal atelectasis and ventral aeration ("baby lung"). Positive airway pressure is often used to recruit atelectasis, but often overinflates ventral (already aerated) regions. A novel approach to selective recruitment of dorsal atelectasis is by "continuous negative abdominal pressure." METHODS: A randomized laboratory study was performed in anesthetized pigs...
April 27, 2018: Anesthesiology
https://www.readbyqxmd.com/read/29680680/pneumolabyrinth-intracochlear-and-vestibular-fluid-loss-after-cochlear-implantation
#6
Hideaki Moteki, Yasunari Fujinaga, Tetsuya Goto, Shin-Ichi Usami
The present case was a 38-year-old male who presented with progressive hearing loss, resulting in profound bilateral hearing loss. He had a past history of childhood medulloblastoma, which was treated with posterior fossa craniotomy and radiotherapy. A ventriculoperitoneal (VP) shunt was put in place to manage the hydrocephalus. Cochlear implantation (CI) was carried out on his right ear by a standard procedure. At CI activation, the electric impedance of the electrode was very high, and computed tomography revealed that there was no area of liquid density, suggesting depletion of the perilymph in the cochlea and vestibule...
April 18, 2018: Auris, Nasus, Larynx
https://www.readbyqxmd.com/read/29667932/fused-data-transrectal-eit-for-prostate-cancer-imaging
#7
Ethan K Murphy, Xiaotian Wu, Ryan J Halter
OBJECTIVE: Prostate cancer is a significant problem affecting 1 in 7 men. Unfortunately, the diagnostic gold-standard of ultrasound-guided biopsy misses 10-30% of all cancers. The objective of this study was to develop an Electrical Impedance Tomography (EIT) approach that has the potential to image the entire prostate using multiple impedance measurements recorded between electrodes integrated onto an end-fired transrectal ultrasound (TRUS) device and a biopsy probe (BP). APPROACH: Simulations and sensitivity analyses were used to investigate the best combination of electrodes, and measured tank experiments were used to evaluate a fused-data transrectal EIT (fd-TREIT) and BP approach...
April 18, 2018: Physiological Measurement
https://www.readbyqxmd.com/read/29621032/electrical-impedance-tomography-for-confirmation-of-lung-isolation-during-one-lung-ventilation-erratum
#8
(no author information available yet)
No abstract text is available yet for this article.
April 5, 2018: Anesthesiology
https://www.readbyqxmd.com/read/29614341/lung-pathologies-analyzed-with-multi-frequency-electrical-impedance-tomography-pilot-animal-study
#9
Susana Aguiar Santos, Michael Czaplik, Jakob Orschulik, Nadine Hochhausen, Steffen Leonhardt
In critically ill patients, correct diagnosis of lung disease is essential for successful therapy. Therefore, this study investigated whether new multi-frequency electrical impedance tomography (mfEIT) can detect, monitor and differentiate between pathologies associated with the acute respiratory distress syndrome (ARDS). For this pilot study, 12 pigs were randomized into an ARDS (bronchoalveolar lavage) group (n=7) and a healthy control group (n=5). Animals were monitored by means of mfEIT. In addition to functional images, a new impaired-ventilation (rImpVent) index was developed and frequency-difference images were computed and analyzed...
March 31, 2018: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/29610075/low-frequency-conductivity-tensor-imaging-of-the-human-head-in-vivo-using-dt-mreit-first-study
#10
Munish Chauhan, Aprinda Indahlastari, Aditya K Kasinadhuni, Michael Schar, Thomas H Mareci, Rosalind J Sadleir
We present the first in vivo images of anisotropic conductivity distribution in the human head, measured at a frequency of approximately 10 Hz. We used magnetic resonance electrical impedance tomography techniques to encode phase changes caused by current flow within the head via two independent electrode pairs. These results were then combined with diffusion tensor imaging data to reconstruct full anisotropic conductivity distributions in 5-mm-thick slices of the brains of two participants. Conductivity values recovered in this paper were broadly consistent with literature values...
April 2018: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/29597327/a-simultaneous-and-continuous-excitation-method-for-high-speed-electrical-impedance-tomography-with-reduced-transients-and-noise-sensitivity
#11
Antoine Dupré, Saba Mylvaganam
This paper presents a concept for soft field tomographic scan of all the projections of electromagnetic waves emanating from an array of electrodes. Instead of the sequential excitation of all pairs of electrodes in the list of all projections, the new method present here consists of a single and continuous excitation. This excitation signal is the linear combination of the excitation signals in the projection set at different AC frequencies. The response to a given projection is discriminated by selecting the corresponding AC frequency component in the signal spectra of the digitally demodulated signals...
March 28, 2018: Sensors
https://www.readbyqxmd.com/read/29578863/electrical-impedance-tomography-for-confirmation-of-lung-isolation-during-one-lung-ventilation
#12
Gunther Hempel, Gero Schulze, Hubert Wirtz, Hermann Wrigge
No abstract text is available yet for this article.
April 5, 2018: Anesthesiology
https://www.readbyqxmd.com/read/29565263/evaluation-of-surrogate-measures-of-pulmonary-function-derived-from-electrical-impedance-tomography-data-in-children-with-cystic-fibrosis
#13
Peter A Muller, Jennifer L Mueller, Michelle Mellenthin, Rashmi Murthy, Michael Capps, Brandie Wagner, Melody Alsaker, Robin Deterding, Scott D Sagel, Jordana Hoppe
Lung function monitoring by spiromety plays a critical role in the clinical care of pediatric cystic fibrosis (CF) patients, but many young children are unable to perform spirometry, and the outputs are often normal even in the presence of lung disease. Measures derived from electrical impedance tomography (EIT) images were studied for their utility as potential surrogates for spirometry in CF patients and to assess response to intravenous antibiotic treatment for acute pulmonary exacerbations (PEx) in a subset of patients...
March 22, 2018: Physiological Measurement
https://www.readbyqxmd.com/read/29564137/regional-overdistension-during-prone-positioning-in-a-patient-with-acute-respiratory-failure-who-was-ventilated-with-a-low-tidal-volume-a-case-report
#14
Toru Kotani, Masanori Hanaoka, Shinya Hirahara, Hisashi Yamanaka, Eckhard Teschner, Atsuko Shono
Background: Prone positioning may provide a uniform distribution of transpulmonary pressure and contribute to prevent ventilator-induced lung injury. However, despite moderate positive end-expiratory pressure and low tidal volumes, there is still a risk of regional overdistension. Case presentation: A man with refractory hypoxemia was mechanically ventilated with prone positioning. Although prone positioning with a plateau pressure of 18 cmH2 O and a positive end-expiratory pressure of 8 cmH2 O promptly improved oxygenation, regional ventilation monitoring using electrical impedance tomography initially detected decreased distribution in the dorsal region but increased in the ventral, suggesting overdistension...
2018: Journal of Intensive Care
https://www.readbyqxmd.com/read/29556346/non-invasive-electrical-impedance-tomography-for-multi-scale-detection-of-liver-fat-content
#15
Yuan Luo, Parinaz Abiri, Shell Zhang, Chih-Chiang Chang, Amir H Kaboodrangi, Rongsong Li, Ashish K Sahib, Alex Bui, Rajesh Kumar, Mary Woo, Zhaoping Li, René R Sevag Packard, Yu-Chong Tai, Tzung K Hsiai
Introduction: Obesity is associated with an increased risk of nonalcoholic fatty liver disease (NAFLD). While Magnetic Resonance Imaging (MRI) is a non-invasive gold standard to detect fatty liver, we demonstrate a low-cost and portable electrical impedance tomography (EIT) approach with circumferential abdominal electrodes for liver conductivity measurements. Methods and Results: A finite element model (FEM) was established to simulate decremental liver conductivity in response to incremental liver lipid content...
2018: Theranostics
https://www.readbyqxmd.com/read/29547133/a-model-of-electrical-impedance-tomography-implemented-in-nerve-cuff-for-neural-prosthetics-control
#16
James Hope, Frederique Vanholsbeeck, A J McDaid
In neural interfaces for peripheral nerve a trade-off exists between the level of invasiveness and the selectivity of neural recordings. In this study, we implement electrical impedance tomography (EIT) in a nerve cuff with the aim to investigate the achievable level of selectivity.
 Approach: Established modelling approaches in neural-EIT are expanded on to be used, for the first time, on myelinated fibres which are abundant in mammalian peripheral nerves and transmit motor commands. The model is then used to evaluate the viability of using EIT with a nerve cuff to record neural activity in peripheral nerves...
March 16, 2018: Physiological Measurement
https://www.readbyqxmd.com/read/29533921/symmetry-difference-electrical-impedance-tomography-a-novel-modality-for-anomaly-detection
#17
Barry McDermott, Emily Porter, Marggie Jones, Brian McGinley, Martin O'Halloran
OBJECTIVE: The theoretical basis, experimental implementation, and proof of concept of a novel electrical impedance tomography (EIT) imaging technique, called symmetry difference EIT, is described. This technique is applicable in situations where there is inherent symmetry in the region being imaged. METHODS: The sample scenario of the human head is used to describe the technique. The head is largely symmetrical across the sagittal plane. A unilateral lesion such as a haemorrhage or region of ischaemia distorts that symmetry...
April 26, 2018: Physiological Measurement
https://www.readbyqxmd.com/read/29533919/finite-element-modelling-and-image-reconstruction-for-lorentz-force-electrical-impedance-tomography
#18
Nick Polydorides
OBJECTIVE: We propose a numerical framework to simulate the Lorentz force electrical impedance tomography (LFEIT) measurements on accurate electrode models and an image reconstruction scheme for which data on two pairs of electrodes are sufficient. APPROACH: The adopted finite element-based complete electrode model encompasses the electrode's geometry and contact impedance, accounting for the power losses at the contact interface. For image reconstruction, we suggest an approach based on a modified J-substitution algorithm that requires LFEIT and impedance measurements on two pairs of sensors, essentially necessitating no more than three boundary electrodes...
April 26, 2018: Physiological Measurement
https://www.readbyqxmd.com/read/29521020/frequency-dependent-anisotropic-modeling-and-analysis-using-mfeit-a-computer-simulation-study
#19
Tingting Zhang, Rihui Li, Thomas Potter, Jin Keun Seo, Guanglin Li, Yingchun Zhang
Electrical properties of human tissues are usually linked with structure of thin insulating membranes and thereby reflect physiological function of the tissues or organs. It is clinically important to characterize electrical properties of tissues in vivo. Electrical impedance tomography is a recently developed medical imaging technique, which has been exploited to characterize electrical properties (conductivity and permittivity) of human tissues by injecting currents and measuring the resulting voltages at boundary electrodes...
March 8, 2018: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/29516865/clinical-performance-of-a-novel-textile-interface-for-neonatal-chest-electrical-impedance-tomography
#20
L Sophocleous, I Frerichs, M Miedema, M Kallio, T Papadouri, C Karaoli, T Becher, D G Tingay, A H van Kaam, R Bayford, A D Waldmann
OBJECTIVE: Critically ill neonates and infants might particularly benefit from continuous chest electrical impedance tomography (EIT) monitoring at the bedside. In this study a textile 32-electrode interface for neonatal EIT examination has been developed and tested to validate its clinical performance. The objectives were to assess ease of use in a clinical setting, stability of contact impedance at the electrode-skin interface and possible adverse effects. APPROACH: Thirty preterm infants (gestational age: 30...
April 26, 2018: Physiological Measurement
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