A 3-D impedance method to calculate power deposition in biological bodies subjected to time varying magnetic fields

Orcutt, N.; Gandhi, O.P.

doi:10.1109/10.4590

Cited by 163 publications

(70 citation statements)

References 4 publications

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“…For the calculations of simulated electric current field in the human head model, we used a 3-D impedance method [27][28][29]. The head model is described using a uniform 3-D Cartesian grid and composed of small cubical cells, called voxels, 1x1x1 mm.…”

Section: B Impedance Methodsmentioning

confidence: 99%

Electrical Bioimpedance Cerebral Monitoring. A Study of the Current Density Distribution and Impedance Sensitivity Maps on a 3D Realistic Head Model

Seoane

Lindecrantz

2007

2007 3rd International IEEE/EMBS Conference on Neural Engineering

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Abstract-There have been several studies of the application of electrical bioimpedance technology for brain monitoring in the past years. They have targeted a variety of events and injuries e.g. epilepsy or stroke. The current density distribution and the voltage lead field associated with an impedance measurement setup is of critical importance for the proper analysis of any dynamics in the impedance measurement or for an accurate reconstruction of an EIT image, specially a dynamic type. In this work for the first time, the current density distribution is calculated in a human head with anatomical accuracy and resolution down to 1 mm, containing up to 24 tissues and considering the frequency dependency of the conductivity of each tissue. The obtained current densities and the subsequent sensitivity maps are analyzed with a special focus on the dependency of the electrode arrangement and also the measurement frequency. The obtained results provide us with interesting and relevant information to consider in the design of any tool for Electrical Bioimpedance Cerebral Monitoring.

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Section: B Impedance Methodsmentioning

confidence: 99%

Electrical Bioimpedance Cerebral Monitoring. A Study of the Current Density Distribution and Impedance Sensitivity Maps on a 3D Realistic Head Model

Seoane

Lindecrantz

2007

2007 3rd International IEEE/EMBS Conference on Neural Engineering

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“…For low-frequency dosimetry problems, the impedance method has been found to be highly efficient as a numerical procedure for calculations of internal current densities and induced electric fields [Armitage et al, 1983;Gandhi et al, 1984;DeFord and Gandhi, 1985;Orcutt and Gandhi, 1988;Tofani et al, 19951. In this method, the biological body or the exposed part thereof is represented by a three-dimensional (3-D) network of impedances whose individual values are obtained from the complex conductivities (3 + j o e for the various locations of the body.…”

Section: Impedance Methodsmentioning

confidence: 99%

Spectral analysis of magnetic fields from domestic appliances and corresponding induced current densities in an anatomically based model of the human head

Tofani

Anglesio

Ossola

et al. 1995

Bioelectromagnetics

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Magnetic fields emitted by electric appliances such as razors, hair dryers, and drills were measured in the frequency domain. Results show the presence of high-frequency components (up to 96 kHz for razors, up to 3.4 kHz for hair dryers, and up to 8.6 kHz for drills) in the harmonic content of the fields. The measured fields were used to calculate the induced current densities in an anatomically based model of the human head (resolution 1.31 cm) by using the impedance method. The harmonic field contribution to the current density was higher than that from the carrier frequency for all the tested appliances.

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Section: B Impedance Methodsmentioning

confidence: 99%

Electrical Bioimpedance Cerebral Monitoring

Seoane

Lindecrantz

2008

Encyclopedia of Healthcare Information Systems

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-i - A B S T R A C TNeurologically related injuries cause a similar number of deaths as cancer, and brain damage is the second commonest cause of death in the world and probably the leading cause of permanent disability. The devastating effects of most cases of brain damage could be avoided if it were detected and medical treatment initiated in time. The passive electrical properties of biological tissue have been investigated for almost a century and electrical bioimpedance studies in neurology have been performed for more than 50 years. Even considering the extensive efforts dedicated to investigating potential applications of electrical bioimpedance for brain monitoring, especially in the last 20 years, and the specifically acute need for such non-invasive and efficient diagnosis support tools, Electrical Bioimpedance technology has not made the expected breakthrough into clinical application yet. In order to reach this stage in the age of evidence-based medicine, the first essential step is to demonstrate the biophysical basis of the method under study. The present research work confirms that the cell swelling accompanying the hypoxic/ischemic injury mechanism modifies the electrical properties of brain tissue, and shows that by measuring the complex electrical bioimpedance it is possible to detect the changes resulting from brain damage. For the development of a successful monitoring method, after the vital biophysical validation it is critical to have available the proper electrical bioimpedance technology and to implement an efficient protocol of use. Electronic instrumentation is needed for broadband spectroscopy measurements of complex electrical bioimpedance; the selection of the electrode setup is crucial to obtain clinically relevant measurements, and the proper biosignal analysis and processing is the core of the diagnosis support system. This work has focused on all these aspects since they are fundamental for providing the solid medico-technological background necessary to enable the clinical usage of Electrical Bioimpedance for cerebral monitoring.Keywords: Electrical Bioimpedance Spectroscopy, Hypoxia, Ischemia, Stroke, Brain Monitoring, Impedance Measurements, Biomedical Instrumentation, Non-invasive Monitoring.-iiPreface -iii - P R E F A C EThis research work has been performed mainly in collaboration between the following research and academic institutions: the School of Engineering at University College of Borås, the Department of Signals and Systems at Chalmers University of Technology, the Sahlgrenska University Hospital, and the Sahlgrenska Academy at Göteborg University.Specific activities of this research work have been carried out in collaboration with the Department of Electronic Engineering at the Polytechnic University of Catalonia, Spain.This research work has been mainly funded by the Swedish Research Council (Vetenskapsrådet) through a research grant (No. 2002-5487). The research activity performed has also been part of the following European Network of Excellence: "Comp...

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A 3-D impedance method to calculate power deposition in biological bodies subjected to time varying magnetic fields

Cited by 163 publications

References 4 publications

Electrical Bioimpedance Cerebral Monitoring. A Study of the Current Density Distribution and Impedance Sensitivity Maps on a 3D Realistic Head Model

Electrical Bioimpedance Cerebral Monitoring. A Study of the Current Density Distribution and Impedance Sensitivity Maps on a 3D Realistic Head Model

Spectral analysis of magnetic fields from domestic appliances and corresponding induced current densities in an anatomically based model of the human head

Electrical Bioimpedance Cerebral Monitoring

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