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Murthy R, Lin YH, Shin K, Mueller JL. A DIRECT RECONSTRUCTION ALGORITHM FOR THE ANISOTROPIC INVERSE CONDUCTIVITY PROBLEM BASED ON CALDERÓN'S METHOD IN THE PLANE. INVERSE PROBLEMS 2020; 36:125008. [PMID: 33353992 PMCID: PMC7751953 DOI: 10.1088/1361-6420/abbe5f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A direct reconstruction algorithm based on Calderón's linearization method for the reconstruction of isotropic conductivities is proposed for anisotropic conductivities in two-dimensions. To overcome the non-uniqueness of the anisotropic inverse conductivity problem, the entries of the unperturbed anisotropic tensors are assumed known a priori, and it remains to reconstruct the multiplicative scalar field. The quasi-conformal map in the plane facilitates the Calderón-based approach for anisotropic conductivities. The method is demonstrated on discontinuous radially symmetric conductivities of high and low contrast.
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Affiliation(s)
- Rashmi Murthy
- Department of Mathematics, University of Helsinki, Finland
| | - Yi-Hsuan Lin
- Department of Applied Mathematics, National Chiao Tung University, Hsinchu, Taiwan
| | - Kwancheol Shin
- Department of Mathematics, Colorado State University, USA
| | - Jennifer L Mueller
- Department of Mathematics and School of Biomedical Engineering, Colorado State University, USA
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Khalighi M, Mikaeili M. Modified weighted back-projection algorithm (MWBP) for 3D electrical impedance mammography systems with the planar electrode array. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/ab4ec2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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de Castro Martins T, Sato AK, de Moura FS, de Camargo EDLB, Silva OL, Santos TBR, Zhao Z, Möeller K, Amato MBP, Mueller JL, Lima RG, de Sales Guerra Tsuzuki M. A Review of Electrical Impedance Tomography in Lung Applications: Theory and Algorithms for Absolute Images. ANNUAL REVIEWS IN CONTROL 2019; 48:442-471. [PMID: 31983885 PMCID: PMC6980523 DOI: 10.1016/j.arcontrol.2019.05.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Electrical Impedance Tomography (EIT) is under fast development, the present paper is a review of some procedures that are contributing to improve spatial resolution and material properties accuracy, admitivitty or impeditivity accuracy. A review of EIT medical applications is presented and they were classified into three broad categories: ARDS patients, obstructive lung diseases and perioperative patients. The use of absolute EIT image may enable the assessment of absolute lung volume, which may significantly improve the clinical acceptance of EIT. The Control Theory, the State Observers more specifically, have a developed theory that can be used for the design and operation of EIT devices. Electrode placement, current injection strategy and electrode electric potential measurements strategy should maximize the number of observable and controllable directions of the state vector space. A non-linear stochastic state observer, the Unscented Kalman Filter, is used directly for the reconstruction of absolute EIT images. Historically, difference images were explored first since they are more stable in the presence of modelling errors. Absolute images require more detailed models of contact impedance, stray capacitance and properly refined finite element mesh where the electric potential gradient is high. Parallelization of the forward program computation is necessary since the solution of the inverse problem often requires frequent solutions of the forward problem. Several reconstruction algorithms benefit by the Bayesian inverse problem approach and the concept of prior information. Anatomic and physiologic information are used to form the prior information. An already tested methodology is presented to build the prior probability density function using an ensemble of CT scans and in vivo impedance measurements. Eight absolute EIT image algorithms are presented.
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Affiliation(s)
| | - André Kubagawa Sato
- Computational Geometry Laboratory, Escola Politécnica da Universidade de São Paulo, Brazil
| | - Fernando Silva de Moura
- Universidade Federal do ABC, Center of Engineering, Modeling and Applied Social Sciences, Brazil
| | | | - Olavo Luppi Silva
- Universidade Federal do ABC, Center of Engineering, Modeling and Applied Social Sciences, Brazil
| | | | - Zhanqi Zhao
- Institute of Technical Medicine, Furtwangen University, Germany
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Knut Möeller
- Institute of Technical Medicine, Furtwangen University, Germany
| | - Marcelo Brito Passos Amato
- Respiratory Intensive Care Unit, Pulmonary Division, Hospital das Clínicas, Universidade de São Paulo, Brazil
| | - Jennifer L Mueller
- Department of Mathematics, and School of Biomedical Engineering, Colorado State University, United States of America
| | - Raul Gonzalez Lima
- Department of Mechanical Engineering, Escola Politécnica da Universidade de São Paulo, Brazil
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Optimal combination of electrodes and conductive gels for brain electrical impedance tomography. Biomed Eng Online 2018; 17:186. [PMID: 30572888 PMCID: PMC6302411 DOI: 10.1186/s12938-018-0617-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 12/12/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Electrical impedance tomography (EIT) is an emerging imaging technology that has been used to monitor brain injury and detect acute stroke. The time and frequency properties of electrode-skin contact impedance are important for brain EIT because brain EIT measurement is performed over a long period when used to monitor brain injury, and is carried out across a wide range of frequencies when used to detect stroke. To our knowledge, no study has simultaneously investigated the time and frequency properties of both electrode and conductive gel for brain EIT. METHODS In this study, the contact impedance of 16 combinations consisting of 4 kinds of clinical electrode and five types of commonly used conductive gel was measured on ten volunteers' scalp for a period of 1 h at frequencies from 100 Hz to 1 MHz using the two-electrode method. And then the performance of each combination was systematically evaluated in terms of the magnitude of contact impedance, and changes in contact impedance with time and frequency. RESULTS Results showed that combination of Ag+/Ag+Cl- powder electrode and low viscosity conductive gel performed best overall (Ten 20® in this study); it had a relatively low magnitude of contact impedance and superior performance regarding contact impedance with time (p < 0.05) and frequency (p < 0.05). CONCLUSIONS Experimental results indicates that the combination of Ag+/Ag+Cl- powder electrode and low viscosity conductive gel may be the best choice for brain EIT.
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Packham B, Barnes G, Dos Santos GS, Aristovich K, Gilad O, Ghosh A, Oh T, Holder D. Empirical validation of statistical parametric mapping for group imaging of fast neural activity using electrical impedance tomography. Physiol Meas 2016; 37:951-67. [PMID: 27203477 PMCID: PMC5717540 DOI: 10.1088/0967-3334/37/6/951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Electrical impedance tomography (EIT) allows for the reconstruction of internal conductivity from surface measurements. A change in conductivity occurs as ion channels open during neural activity, making EIT a potential tool for functional brain imaging. EIT images can have >10 000 voxels, which means statistical analysis of such images presents a substantial multiple testing problem. One way to optimally correct for these issues and still maintain the flexibility of complicated experimental designs is to use random field theory. This parametric method estimates the distribution of peaks one would expect by chance in a smooth random field of a given size. Random field theory has been used in several other neuroimaging techniques but never validated for EIT images of fast neural activity, such validation can be achieved using non-parametric techniques. Both parametric and non-parametric techniques were used to analyze a set of 22 images collected from 8 rats. Significant group activations were detected using both techniques (corrected p < 0.05). Both parametric and non-parametric analyses yielded similar results, although the latter was less conservative. These results demonstrate the first statistical analysis of such an image set and indicate that such an analysis is an approach for EIT images of neural activity.
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Affiliation(s)
- B Packham
- Department of Medical Physics & Bioengineering, University College London, UK
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Chen X, Kao TJ, Ashe JM, Boverman G, Sabatini JE, Davenport DM. Multi-channel electrical impedance tomography for regional tissue hydration monitoring. Physiol Meas 2014; 35:1137-47. [DOI: 10.1088/0967-3334/35/6/1137] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Zhao M, Wi H, Mostofa Kamal AH, McEwan AL, Woo EJ, Oh TI. High density trans-admittance mammography development and preliminary phantom tests. Biomed Eng Online 2012; 11:75. [PMID: 23009288 PMCID: PMC3537578 DOI: 10.1186/1475-925x-11-75] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 09/05/2012] [Indexed: 11/29/2022] Open
Abstract
Background Malignant breast tumor tissue has a significantly different electrical impedance spectrum than surrounding normal tissues. This has led to the development of impedance imaging as a supplementary or alternative method to X-ray mammography for screening and assessment of breast cancers. However low spatial resolution and poor signal to noise ratio has limited the clinical application. Methods In order to improve spatial resolution we developed a trans-admittance mammography (TAM) system including an array of 60×60 current sensing electrodes. We adopted a similar setup to X-ray mammography where the breast is situated between two holding plates. The top plate is a large solid metal electrode for applying a sinusoidal voltage over a range of frequencies from 50 Hz to 500 kHz. The bottom plate has 3600 current sensing electrodes that are kept at the ground potential. Currents are generated from the top voltage-applying electrode and spread throughout the breast, entering the TAM system through the array of current sensing electrodes on the bottom plate. The TAM system measures the exit currents through 6 switching modules connected to 600 electrodes each. Each switching module is connected to 12 ammeter channels which are switched sequentially to 50 of the 600 electrodes each measurement time. Each ammeter channel is comprised of a current-to-voltage converter, a gain amplifier, filters, an analog to digital converter, and a digital phase sensitive demodulator. Results We found an average noise level of 38 nA, amplitude stability of less than 0.2%, crosstalk of better than -60 dB and 70 dB signal to noise ratio over all channels and operating frequencies. Images were obtained in time difference and frequency difference modes in a saline phantom. Conclusion We describe the design, construction, and calibration of a high density TAM system in detail. Successful high resolution time and frequency difference images showed regions of interest with the expected admittivity changes in the frequency spectrum.
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Affiliation(s)
- Mingkang Zhao
- Department of Biomedical Engineering, Kyung Hee University, Yongin-si, Gyeonggi-do 446-701, Korea
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V A C, Y V G, A V K, S A S, T S T. An electrical impedance tomography system for gynecological application GIT with a tiny electrode array. Physiol Meas 2012; 33:849-62. [PMID: 22531280 DOI: 10.1088/0967-3334/33/5/849] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The paper describes the development of an electrical impedance tomography (EIT) system for gynecologic research. The GIT (gynecological impedance tomography) system has 48 electrodes and is embedded on a small space (30 mm diameter and 20 mm height) inside of the vaginal probe. The system provides real-time (one shot per second) 3D visualization of the spatial distribution of the static electrical properties of the cervix tissue. History, advantages, disadvantages and aspects of the system development are also described. The algorithm for the tiny measuring array organization is given. New details of the backprojection method on the non-regular electrode array are discussed. Some pictures reconstructed from numerical simulated data are offered. 3D visualization of the test object and cervix is presented.
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Affiliation(s)
- Cherepenin V A
- Kotel'nikov Institute of Radioengineering and Electronics, RAS, Moscow, Russia
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Martins TDC, de Camargo EDLB, Lima RG, Amato MBP, Tsuzuki MDSG. Image reconstruction using interval simulated annealing in electrical impedance tomography. IEEE Trans Biomed Eng 2012; 59:1861-70. [PMID: 22361655 DOI: 10.1109/tbme.2012.2188398] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Electrical impedance tomography (EIT) is an imaging technique that attempts to reconstruct the impedance distribution inside an object from the impedance between electrodes placed on the object surface. The EIT reconstruction problem can be approached as a nonlinear nonconvex optimization problem in which one tries to maximize the matching between a simulated impedance problem and the observed data. This nonlinear optimization problem is often ill-posed, and not very suited to methods that evaluate derivatives of the objective function. It may be approached by simulated annealing (SA), but at a large computational cost due to the expensive evaluation process of the objective function, which involves a full simulation of the impedance problem at each iteration. A variation of SA is proposed in which the objective function is evaluated only partially, while ensuring boundaries on the behavior of the modified algorithm.
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Affiliation(s)
- Thiago de Castro Martins
- Department of Mechatronics and Mechanical Systems Engineering, Escola Politécnica University of São Paulo, São Paulo 05508-030, Brazil.
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Kantartzis P, Liatsis P. On sparse forward solutions in non-stationary domains for the EIT imaging problem. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2011; 2011:3892-3896. [PMID: 22255190 DOI: 10.1109/iembs.2011.6090967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In the forward EIT-problem numerical solutions of an elliptic partial differential equation are required. Given the arbitrary geometries encountered, the Finite Element Method (FEM) is, naturally, the method of choice. Nowadays, in EIT applications, there is an increasing demand for finer Finite Element mesh models. This in turn results to a soaring number of degrees of freedom and an excessive number of unknowns. As such, only piece-wise linear basis functions can practically be employed to maintain inexpensive computations. In addition, domain reduction and/or compression schemes are often sought to further counteract for the growing number of unknowns. In this paper, we replace the piece-wise linear with wavelet basis functions (coupled with the domain embedding method) to enable sparse approximations of the forward computations. Given that the forward solutions are repeatedly, if not extensively, utilised during the image reconstruction process, considerable computational savings can be recorded whilst maintaining O(N) forward problem complexity. We verify with numerical results that, in practice, less than 5% of the involved coefficients are actually required for computations and, hence, needs to be stored. We finalise this work by addressing the impact to the inverse problem. It is worth underlining that the proposed scheme is independent of the actual family of wavelet basis functions of compact support.
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Affiliation(s)
- Panagiotis Kantartzis
- Information Engineering and Medical Imaging Group, City University London, Northampton square, EC1V 0HB London, UK.
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Habibi M, Klemer DP, Raicu V. Two-dimensional dielectric spectroscopy: implementation and validation of a scanning open-ended coaxial probe. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:075108. [PMID: 20687760 DOI: 10.1063/1.3462974] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Dielectric spectroscopy is a powerful tool for characterizing and classifying materials based on their electrical properties. In order to perform dielectric measurements on a sample with spatially varying properties, the measuring probe typically is repositioned manually on the surface of the sample for each measurement. In this paper, we present a novel technique, based on a reconfigurable multielectrode array, which facilitates the recording of measurements at various different spatial locations without physically moving the measuring electrodes. By electronically selecting one of the electrodes as the inner line and connecting the remainder of the electrodes together to form the outer line, an open-ended coaxial probe is created, which can be repositioned by simply selecting different electrode combinations; hence the name of a "traveling" coaxial probe. The geometric factor, or the cell constant, of each coaxial probe in the array was estimated from measurements on saline solutions with known electrical characteristics. In order to validate the setup for measurement of dielectric properties of biological cells, the plasma membrane capacitance and cytoplasm conductivity of yeast cells suspended in aqueous solutions were measured and compared to results from published reports. Dielectric spectroscopy imaging was carried out on tissue phantoms made of an agar gel with inclusions consisting of concentrated yeast cell suspensions. Measurements were performed on the phantoms, and the dielectric data were spatially mapped with respect to electrode location. The spatial electrical data correlated precisely with locations of yeast cell inclusions within the phantoms.
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Affiliation(s)
- Mohammad Habibi
- Department of Electrical Engineering, University of Wisconsin, Milwaukee, Wisconsin 53211, USA
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Kao TJ, Boverman G, Kim BS, Isaacson D, Saulnier GJ, Newell JC, Choi MH, Moore RH, Kopans DB. Regional admittivity spectra with tomosynthesis images for breast cancer detection: preliminary patient study. IEEE TRANSACTIONS ON MEDICAL IMAGING 2008; 27:1762-8. [PMID: 19033092 PMCID: PMC2758037 DOI: 10.1109/tmi.2008.926049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
It has been known for some time that many tumors have a significantly different conductivity and permittivity from surrounding normal tissue. This high "contrast" in tissue electrical properties, occurring between a few kilohertz and several megahertz, may permit differentiating malignant from benign tissues. Here we show the ability of electrical impedance spectroscopy (EIS) to roughly localize and clearly distinguish cancers from normal tissues and benign lesions. Localization of these lesions is confirmed by simultaneous, in register digital breast tomosynthesis (DBT) mammography or 3-D mammograms.
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Affiliation(s)
- Tzu-Jen Kao
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 USA
| | - Gregory Boverman
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 USA
| | - Bong Seok Kim
- National Cancer Center, Gyeonggi-do 410-769, South Korea
| | - David Isaacson
- Department of Mathematical Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180 USA
| | - Gary J. Saulnier
- Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 USA
| | - Jonathan C. Newell
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 USA
| | - Myoung H. Choi
- Department of Electrical and Electronics Engineering, Kangwon National University, Kangwondo 200-701, Korea
| | - Richard H. Moore
- Department of Radiology, Massachusetts General Hospital, Boston, MA 02114 USA
| | - Daniel B. Kopans
- Department of Radiology, Massachusetts General Hospital, Boston, MA 02114 USA
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Abstract
Multiple biomedical imaging techniques are used in all phases of cancer management. Imaging forms an essential part of cancer clinical protocols and is able to furnish morphological, structural, metabolic and functional information. Integration with other diagnostic tools such as in vitro tissue and fluids analysis assists in clinical decision-making. Hybrid imaging techniques are able to supply complementary information for improved staging and therapy planning. Image guided and targeted minimally invasive therapy has the promise to improve outcome and reduce collateral effects. Early detection of cancer through screening based on imaging is probably the major contributor to a reduction in mortality for certain cancers. Targeted imaging of receptors, gene therapy expression and cancer stem cells are research activities that will translate into clinical use in the next decade. Technological developments will increase imaging speed to match that of physiological processes. Targeted imaging and therapeutic agents will be developed in tandem through close collaboration between academia and biotechnology, information technology and pharmaceutical industries.
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Affiliation(s)
- Leonard Fass
- GE Healthcare, 352 Buckingham Avenue, Slough, SL1 4ER, UK.
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Granot Y, Ivorra A, Rubinsky B. A new concept for medical imaging centered on cellular phone technology. PLoS One 2008; 3:e2075. [PMID: 18446199 PMCID: PMC2312332 DOI: 10.1371/journal.pone.0002075] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Accepted: 03/18/2008] [Indexed: 12/16/2022] Open
Abstract
According to World Health Organization reports, some three quarters of the world population does not have access to medical imaging. In addition, in developing countries over 50% of medical equipment that is available is not being used because it is too sophisticated or in disrepair or because the health personnel are not trained to use it. The goal of this study is to introduce and demonstrate the feasibility of a new concept in medical imaging that is centered on cellular phone technology and which may provide a solution to medical imaging in underserved areas. The new system replaces the conventional stand-alone medical imaging device with a new medical imaging system made of two independent components connected through cellular phone technology. The independent units are: a) a data acquisition device (DAD) at a remote patient site that is simple, with limited controls and no image display capability and b) an advanced image reconstruction and hardware control multiserver unit at a central site. The cellular phone technology transmits unprocessed raw data from the patient site DAD and receives and displays the processed image from the central site. (This is different from conventional telemedicine where the image reconstruction and control is at the patient site and telecommunication is used to transmit processed images from the patient site). The primary goal of this study is to demonstrate that the cellular phone technology can function in the proposed mode. The feasibility of the concept is demonstrated using a new frequency division multiplexing electrical impedance tomography system, which we have developed for dynamic medical imaging, as the medical imaging modality. The system is used to image through a cellular phone a simulation of breast cancer tumors in a medical imaging diagnostic mode and to image minimally invasive tissue ablation with irreversible electroporation in a medical imaging interventional mode.
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Affiliation(s)
- Yair Granot
- Biophysics Graduate Group, Department of Bioengineering and Department of Mechanical Engineering, University of California, Berkeley, California, United States of America
| | - Antoni Ivorra
- Biophysics Graduate Group, Department of Bioengineering and Department of Mechanical Engineering, University of California, Berkeley, California, United States of America
| | - Boris Rubinsky
- Biophysics Graduate Group, Department of Bioengineering and Department of Mechanical Engineering, University of California, Berkeley, California, United States of America
- Research Center for Bioengineering in the Service of Humanity and Society, School of Computer Science and Engineering, Hebrew University of Jerusalem, Jerusalem, Israel
- * E-mail:
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Mello LAM, de Lima CÍR, Amato MBP, Lima RG, Silva ECN. Three-Dimensional Electrical Impedance Tomography: A Topology Optimization Approach. IEEE Trans Biomed Eng 2008; 55:531-40. [DOI: 10.1109/tbme.2007.912637] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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16
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Ng EYK, Ng WK, Sim LSJ, Rajendra Acharya U. Numerical modelling of biopotential field for detection of breast tumour. Comput Biol Med 2007; 37:1121-32. [PMID: 17145053 DOI: 10.1016/j.compbiomed.2006.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 09/19/2006] [Accepted: 10/11/2006] [Indexed: 11/19/2022]
Abstract
Breast cancer is a disease characterised by the uncontrolled growth of abnormal cells. These cancer cells can travel through the body by way of blood or lymph nodes. Previous studies have indicated that, changes in the electrical properties of abnormal breast are more significant compared to the breast normal tissues. In the present study, a simple 2D models of breast (close to realistic), with and without artificially inserted malignant cancer were simulated, based upon electrical activity within the breast. We developed an inhomogeneous female breast model, closer to the actual, by considering a breast as a hemisphere with various layers of unequal thickness in supine condition. In order to determine the potential distribution developed due to a dipole source, isotropic homogeneous conductivity was assigned to each of these compartments and the volume conductor problem was solved using finite element method. Significant changes in the potential distribution were recoded in the malignant and normal breast regions. The surface potential decreases about 0.5%, for the small malignant region of surface area 13 mm(2) (spherical diameter=2mm). And it (surface potential) decreases about 16.4% for large malignant surface area of 615 mm(2) (spherical diameter=14 mm). Hence, the results show that, the sizes of tumours result in the reduction of surface potential and follows a fourth order polynomial equation. Thus, biofield analysis yields promising results in the detection of the breast cancer of various sizes.
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Affiliation(s)
- E Y K Ng
- School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore.
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