1
|
Gao Z, Darma PN, Sun B, Kawashima D, Takei M. A noise-controlling method by hybrid current-stimulation and voltage-measurement for electrical impedance tomography (HCSVM-EIT). Biomed Phys Eng Express 2023; 9:065002. [PMID: 37659392 DOI: 10.1088/2057-1976/acf61a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 09/02/2023] [Indexed: 09/04/2023]
Abstract
Image reconstruction in electrical impedance tomography (EIT) is a typical ill-posed inverse problem, from which the stability of conductivity reconstruction affects the reliability of physiological parameters evaluation. In order to improve the stability, the effect of boundary voltage noise on conductivity reconstruction should be controlled. A noise-controlling method based on hybrid current-stimulation and voltage-measurement for EIT (HCSVM-EIT) is proposed for stable conductivity reconstruction. In HCSVM-EIT, the boundary voltage is measured by one current-stimulation and voltage-measurement pattern (high-SNRpattern) with a higher signal-to-noise ratio (SNR); the sensitivity matrix is calculated by another current-stimulation and voltage-measurement pattern (low-condpattern) with a lower condition number; the boundary voltage is then transformed from thehigh-SNRpattern into thelow-condpattern by multiplying by an optimized transformation matrix for image reconstruction. The stability of conductivity reconstruction is improved by combining the advantages of thehigh-SNRpattern for boundary voltage measurement and thelow-condpattern for sensitivity matrix calculation. The simulation results show that the HCSVM-EIT increases the correlation coefficient (CC) of conductivity reconstruction. The experiment results show that theCCof conductivity reconstruction of the human lower limb is increased from 0.3424 to 0.5580 by 62.97% compared to the quasi-adjacent pattern, and from 0.4942 to 0.5580 by 12.91% compared to the adjacent pattern. In conclusion, the stable conductivity reconstruction with higherCCin HCSVM-EIT improves the reliability of physiological parameters evaluation for disease detection.
Collapse
Affiliation(s)
- Zengfeng Gao
- Division of Fundamental Engineering, Graduate School of Science and Engineering, Chiba University, Chiba 263-8522, Japan
| | - Panji Nursetia Darma
- Division of Fundamental Engineering, Graduate School of Engineering, Chiba University, Chiba 263-8522, Japan
| | - Bo Sun
- School of Mechanical and Precision Instrument Engineering, Xi'an University of Technology, Xi'an 710048, People's Republic of China
| | - Daisuke Kawashima
- Division of Fundamental Engineering, Graduate School of Engineering, Chiba University, Chiba 263-8522, Japan
| | - Masahiro Takei
- Division of Fundamental Engineering, Graduate School of Engineering, Chiba University, Chiba 263-8522, Japan
| |
Collapse
|
2
|
Devaraj H, K Murphy E, J Halter R. Design of electrical impedance spectroscopy sensing surgical drill using computational modelling and experimental validation. Biomed Phys Eng Express 2022; 9:10.1088/2057-1976/ac9f4d. [PMID: 36322960 PMCID: PMC9988190 DOI: 10.1088/2057-1976/ac9f4d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 11/02/2022] [Indexed: 11/07/2022]
Abstract
Electrical Impedance Spectroscopy (EIS) sensing surgical instruments could provide valuable and real-time feedback to surgeons about hidden tissue boundaries, therefore reducing the risk of iatrogenic injuries. In this paper, we present an EIS sensing surgical drill as an example instrument and introduce a strategy to optimize the mono-polar electrode geometry using a finite element method (FEM)-based computational model and experimental validation. An empirical contact impedance model and an adaptive mesh refinement protocol were developed to accurately preserve the behaviour of sensing electrodes as they approach high impedance boundaries. Specifically, experiments with drill-bit, cylinder, and conical geometries suggested a 15%-35% increase in resistance as the sensing electrode approached a high impedance boundary. Simulations achieved a maximum mean experiment-to-simulation mismatch of +1.7% for the drill-bit and +/-11% range for other electrode geometries. The simulations preserved the increase in resistance behaviour near the high impedance boundary. This highly accurate simulation framework allows us a mechanism for optimizing sensor geometry without costly experimental evaluation.
Collapse
Affiliation(s)
- Harshavardhan Devaraj
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03766, United States of America
| | - Ethan K Murphy
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03766, United States of America
| | - Ryan J Halter
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03766, United States of America
- Geisel School of Medicine, Dartmouth College, Hanover, NH 03766, United States of America
| |
Collapse
|
3
|
Ogura T. Development of multi-frequency impedance scanning electron microscopy. PLoS One 2022; 17:e0263098. [PMID: 35077509 PMCID: PMC8789111 DOI: 10.1371/journal.pone.0263098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 01/11/2022] [Indexed: 11/23/2022] Open
Abstract
Nanometre-scale observation of specimens in water is indispensable in many scientific fields like biology, chemistry, material science and nanotechnology. Scanning electron microscopy (SEM) allows high-resolution images of biological samples to be obtained under high vacuum conditions but requires specific sample-preparation protocols. Therefore, there is a need for convenient and minimally invasive methods of observing samples in solution. We have developed a new type of impedance microscopy, namely multi-frequency impedance SEM (IP-SEM), which allows nanoscale imaging of various specimens in water while minimising radiation damage. By varying the frequency of the input voltage signal of the sine wave, the present system can detect dielectric properties of the sample’s composition at nanometre resolution. It also enables examination of unstained biological specimens and material samples in water. Furthermore, it can be used for diverse samples in liquids across a broad range of scientific subjects such as nanoparticles, nanotubes and organic and catalytic materials.
Collapse
Affiliation(s)
- Toshihiko Ogura
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan
- * E-mail:
| |
Collapse
|
4
|
Hu CL, Cheng IC, Huang CH, Liao YT, Lin WC, Tsai KJ, Chi CH, Chen CW, Wu CH, Lin IT, Li CJ, Lin CW. Dry Wearable Textile Electrodes for Portable Electrical Impedance Tomography. SENSORS 2021; 21:s21206789. [PMID: 34696002 PMCID: PMC8537054 DOI: 10.3390/s21206789] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 10/08/2021] [Accepted: 10/09/2021] [Indexed: 11/16/2022]
Abstract
Electrical impedance tomography (EIT), a noninvasive and radiation-free medical imaging technique, has been used for continuous real-time regional lung aeration. However, adhesive electrodes could cause discomfort and increase the risk of skin injury during prolonged measurement. Additionally, the conductive gel between the electrodes and skin could evaporate in long-term usage and deteriorate the signal quality. To address these issues, in this work, textile electrodes integrated with a clothing belt are proposed to achieve EIT lung imaging along with a custom portable EIT system. The simulation and experimental results have verified the validity of the proposed portable EIT system. Furthermore, the imaging results of using the proposed textile electrodes were compared with commercial electrocardiogram electrodes to evaluate their performance.
Collapse
Affiliation(s)
- Chang-Lin Hu
- Industrial Technology Research Institute, Hsinchu 310, Taiwan; (I.-C.C.); (K.-J.T.); (C.-J.L.); (C.-W.L.)
- Correspondence:
| | - I-Cheng Cheng
- Industrial Technology Research Institute, Hsinchu 310, Taiwan; (I.-C.C.); (K.-J.T.); (C.-J.L.); (C.-W.L.)
| | - Chih-Hsien Huang
- Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan; (C.-H.H.); (C.-H.W.)
| | - Yu-Te Liao
- Department of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan; (Y.-T.L.); (I.-T.L.)
| | - Wei-Chieh Lin
- Division of Critical Care Medicine, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan; (W.-C.L.); (C.-W.C.)
| | - Kun-Ju Tsai
- Industrial Technology Research Institute, Hsinchu 310, Taiwan; (I.-C.C.); (K.-J.T.); (C.-J.L.); (C.-W.L.)
| | - Chih-Hsien Chi
- Department of Emergency Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan;
| | - Chang-Wen Chen
- Division of Critical Care Medicine, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan; (W.-C.L.); (C.-W.C.)
| | - Chia-Hsi Wu
- Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan; (C.-H.H.); (C.-H.W.)
| | - I-Te Lin
- Department of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan; (Y.-T.L.); (I.-T.L.)
| | - Chien-Ju Li
- Industrial Technology Research Institute, Hsinchu 310, Taiwan; (I.-C.C.); (K.-J.T.); (C.-J.L.); (C.-W.L.)
| | - Chii-Wann Lin
- Industrial Technology Research Institute, Hsinchu 310, Taiwan; (I.-C.C.); (K.-J.T.); (C.-J.L.); (C.-W.L.)
- Department of Biomedical Engineering, National Taiwan University, Taipei 106, Taiwan
| |
Collapse
|
5
|
Measurement-Based Domain Parameter Optimization in Electrical Impedance Tomography Imaging. SENSORS 2021; 21:s21072507. [PMID: 33916751 PMCID: PMC8038345 DOI: 10.3390/s21072507] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/29/2021] [Accepted: 03/31/2021] [Indexed: 12/22/2022]
Abstract
This paper discusses the optimization of domain parameters in electrical impedance tomography-based imaging. Precise image reconstruction requires accurate, well-correlated physical and numerical finite element method (FEM) models; thus, we employed the Nelder–Mead algorithm and a complete electrode model to evaluate the individual parameters, including the initial conductivity, electrode misplacement, and shape deformation. The optimization process was designed to calculate the parameters of the numerical model before the image reconstruction. The models were verified via simulation and experimental measurement with single source current patterns. The impact of the optimization on the above parameters was reflected in the applied image reconstruction process, where the conductivity error dropped by 6.16% and 11.58% in adjacent and opposite driving, respectively. In the shape deformation, the inhomogeneity area ratio increased by 11.0% and 48.9%; the imprecise placement of the 6th electrode was successfully optimized with adjacent driving; the conductivity error dropped by 12.69%; and the inhomogeneity localization exhibited a rise of 66.7%. The opposite driving option produces undesired duality resulting from the measurement pattern. The designed optimization process proved to be suitable for correlating the numerical and the physical models, and it also enabled us to eliminate imaging uncertainties and artifacts.
Collapse
|
6
|
Direct observation of unstained biological samples in water using newly developed impedance scanning electron microscopy. PLoS One 2019; 14:e0221296. [PMID: 31430321 PMCID: PMC6701803 DOI: 10.1371/journal.pone.0221296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 08/03/2019] [Indexed: 11/26/2022] Open
Abstract
Nanometre-scale observation of specimens in water is indispensable in several scientific fields, such as biology, chemistry, materials science and nanotechnology. Scanning electron microscopy (SEM) obtains high-resolution images of biological samples under high vacuum conditions but requires specific sample-preparation protocols. Observations of unstained biological samples in water require more convenient and less invasive methods. Herein, we have developed a new type of impedance microscopy, namely impedance SEM (IP-SEM), which allows the imaging and sub-micrometer scale examination of various specimens in water. By varying the frequency of the input signal, the proposed system can detect the impedance properties of the sample’s composition at sub-micrometer scale resolution. Besides examining various unstained biological specimens and material samples in water. Furthermore, the proposed system can be used for diverse liquid samples across a broad range of scientific fields, such as nanoparticles, nanotubes and organic and catalytic materials.
Collapse
|
7
|
Murphy EK, Amoh J, Arshad SH, Halter RJ, Odame K. Noise-robust bioimpedance approach for cardiac output measurement. Physiol Meas 2019; 40:074004. [PMID: 30840932 DOI: 10.1088/1361-6579/ab0d45] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Congestive heart failure is a problem affecting millions of Americans. A continuous, non-invasive, telemonitoring device that can accurately monitor cardiac metrics could greatly help this population, reducing unnecessary hospitalizations and cost. APPROACH Machine learning (ML) algorithms trained on electrical-impedance tomography (EIT) data are presented for portable cardiac monitoring. The approach was validated on a simulated thorax and a measured tank experiment. A highly detailed 4D chest model (finite element method mesh and conductivity profiles) was developed utilizing the 4D XCAT phantom to provide realistic data. The ML algorithms were trained using databases that assumed the presence of poorly contacting electrodes without any assumptions of knowing which electrodes would be bad in the experiment. The trained ML algorithms were compared to EIT evaluated with and without removing bad electrodes. MAIN RESULTS A regression support vector machine and a deep neural network (DNN) were found to be the most accurate and robust to poorly contacting electrodes while not needing to know which electrodes were in poor contact in the simulated and measured experiments, respectively. SIGNIFICANCE Although the ML algorithms are not always better than EIT (with bad electrodes removed), the comparable results without needing a priori knowledge of which electrodes are bad is seen as a very promising feature. An evaluation of computational costs showed that the DNN required comparable computational power to the other methods while requiring less memory, which could make the DNNs an attractive algorithm for a low-power, portable system. This work represents an important validation of the method using measured data, and model development, which is needed to apply this method on real clinical data. Additionally, the developed 4D simulated thorax model could be an important tool within the EIT community.
Collapse
Affiliation(s)
- Ethan K Murphy
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, United States of America
| | | | | | | | | |
Collapse
|
8
|
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.
Collapse
|
9
|
Yang L, Dai M, Xu C, Zhang G, Li W, Fu F, Shi X, Dong X. The Frequency Spectral Properties of Electrode-Skin Contact Impedance on Human Head and Its Frequency-Dependent Effects on Frequency-Difference EIT in Stroke Detection from 10Hz to 1MHz. PLoS One 2017; 12:e0170563. [PMID: 28107524 PMCID: PMC5249181 DOI: 10.1371/journal.pone.0170563] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 01/08/2017] [Indexed: 11/18/2022] Open
Abstract
Frequency-difference electrical impedance tomography (fdEIT) reconstructs frequency-dependent changes of a complex impedance distribution. It has a potential application in acute stroke detection because there are significant differences in impedance spectra between stroke lesions and normal brain tissues. However, fdEIT suffers from the influences of electrode-skin contact impedance since contact impedance varies greatly with frequency. When using fdEIT to detect stroke, it is critical to know the degree of measurement errors or image artifacts caused by contact impedance. To our knowledge, no study has systematically investigated the frequency spectral properties of electrode-skin contact impedance on human head and its frequency-dependent effects on fdEIT used in stroke detection within a wide frequency band (10 Hz-1 MHz). In this study, we first measured and analyzed the frequency spectral properties of electrode-skin contact impedance on 47 human subjects’ heads within 10 Hz-1 MHz. Then, we quantified the frequency-dependent effects of contact impedance on fdEIT in stroke detection in terms of the current distribution beneath the electrodes and the contact impedance imbalance between two measuring electrodes. The results showed that the contact impedance at high frequencies (>100 kHz) significantly changed the current distribution beneath the electrode, leading to nonnegligible errors in boundary voltages and artifacts in reconstructed images. The contact impedance imbalance at low frequencies (<1 kHz) also caused significant measurement errors. We conclude that the contact impedance has critical frequency-dependent influences on fdEIT and further studies on reducing such influences are necessary to improve the application of fdEIT in stroke detection.
Collapse
Affiliation(s)
- Lin Yang
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Meng Dai
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Canhua Xu
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Ge Zhang
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Weichen Li
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Feng Fu
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Xuetao Shi
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| | - Xiuzhen Dong
- Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China
| |
Collapse
|
10
|
Boverman G, Isaacson D, Newell JC, Saulnier GJ, Kao TJ, Amm BC, Wang X, Davenport DM, Chong DH, Sahni R, Ashe JM. Efficient Simultaneous Reconstruction of Time-Varying Images and Electrode Contact Impedances in Electrical Impedance Tomography. IEEE Trans Biomed Eng 2016; 64:795-806. [PMID: 27295649 DOI: 10.1109/tbme.2016.2578646] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE In electrical impedance tomography (EIT), we apply patterns of currents on a set of electrodes at the external boundary of an object, measure the resulting potentials at the electrodes, and, given the aggregate dataset, reconstruct the complex conductivity and permittivity within the object. It is possible to maximize sensitivity to internal conductivity changes by simultaneously applying currents and measuring potentials on all electrodes but this approach also maximizes sensitivity to changes in impedance at the interface. METHODS We have, therefore, developed algorithms to assess contact impedance changes at the interface as well as to efficiently and simultaneously reconstruct internal conductivity/permittivity changes within the body. We use simple linear algebraic manipulations, the generalized singular value decomposition, and a dual-mesh finite-element-based framework to reconstruct images in real time. We are also able to efficiently compute the linearized reconstruction for a wide range of regularization parameters and to compute both the generalized cross-validation parameter as well as the L-curve, objective approaches to determining the optimal regularization parameter, in a similarly efficient manner. RESULTS Results are shown using data from a normal subject and from a clinical intensive care unit patient, both acquired with the GE GENESIS prototype EIT system, demonstrating significantly reduced boundary artifacts due to electrode drift and motion artifact.
Collapse
|
11
|
Ogura T. Non-destructive observation of intact bacteria and viruses in water by the highly sensitive frequency transmission electric-field method based on SEM. Biochem Biophys Res Commun 2014; 450:1684-9. [DOI: 10.1016/j.bbrc.2014.07.062] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 07/14/2014] [Indexed: 12/21/2022]
|
12
|
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]
|
13
|
Ogura T. Direct observation of unstained biological specimens in water by the frequency transmission electric-field method using SEM. PLoS One 2014; 9:e92780. [PMID: 24651483 PMCID: PMC3961424 DOI: 10.1371/journal.pone.0092780] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 02/25/2014] [Indexed: 11/18/2022] Open
Abstract
Scanning electron microscopy (SEM) is a powerful tool for the direct visualization of biological specimens at nanometre-scale resolution. However, images of unstained specimens in water using an atmospheric holder exhibit very poor contrast and heavy radiation damage. Here, we present a new form of microscopy, the frequency transmission electric-field (FTE) method using SEM, that offers low radiation damage and high-contrast observation of unstained biological samples in water. The wet biological specimens are enclosed in two silicon nitride (SiN) films. The metal-coated SiN film is irradiated using a focused modulation electron beam (EB) at a low-accelerating voltage. A measurement terminal under the sample holder detects the electric-field frequency signal, which contains structural information relating to the biological specimens. Our results in very little radiation damage to the sample, and the observation image is similar to the transmission image, depending on the sample volume. Our developed method can easily be utilized for the observation of various biological specimens in water.
Collapse
Affiliation(s)
- Toshihiko Ogura
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Umezono, Tsukuba, Ibaraki, Japan
- * E-mail:
| |
Collapse
|
14
|
Mamatjan Y, Grychtol B, Gaggero P, Justiz J, Koch VM, Adler A. Evaluation and real-time monitoring of data quality in electrical impedance tomography. IEEE TRANSACTIONS ON MEDICAL IMAGING 2013; 32:1997-2005. [PMID: 23799682 DOI: 10.1109/tmi.2013.2269867] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Electrical impedance tomography (EIT) is a noninvasive method to image conductivity distributions within a body. One promising application of EIT is to monitor ventilation in patients as a real-time bedside tool. Thus, it is essential that an EIT system reliably provide meaningful information, or alert clinicians when this is impossible. Because the reconstructed images are very sensitive to system instabilities (primarily from electrode connection variability and movement), EIT systems should continuously monitor and, if possible, correct for such errors. Motivated by this requirement, we describe a novel approach to quantitatively measure EIT data quality. Our goals are to define the requirements of a data quality metric, develop a metric q which meets these requirements, and an efficient way to calculate it. The developed metric q was validated using data from saline tank experiments and a retrospective clinical study. Additionally, we show that q may be used to compare the performance of EIT systems using phantom measurements. Results suggest that the calculated metric reflects well the quality of reconstructed EIT images for both phantom and clinical data. The proposed measure can thus be used for real-time assessment of EIT data quality and, hence, to indicate the reliability of any derived physiological information.
Collapse
|
15
|
Hassan AM, El-Shenawee M. Review of electromagnetic techniques for breast cancer detection. IEEE Rev Biomed Eng 2012; 4:103-18. [PMID: 22273794 DOI: 10.1109/rbme.2011.2169780] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Breast cancer is anticipated to be responsible for almost 40,000 deaths in the USA in 2011. The current clinical detection techniques suffer from limitations which motivated researchers to investigate alternative modalities for the early detection of breast cancer. This paper focuses on reviewing the main electromagnetic techniques for breast cancer detection. More specifically, this work reviews the cutting edge research in microwave imaging, electrical impedance tomography, diffuse optical tomography, microwave radiometry, biomagnetic detection, biopotential detection, and magnetic resonance imaging (MRI). The goal of this paper is to provide biomedical researchers with an in-depth review that includes all main electromagnetic techniques in the literature and the latest progress in each of these techniques.
Collapse
Affiliation(s)
- Ahmed M Hassan
- Department of Electrical Engineering, University of Arkansas, Fayetteville, AR 72701, USA.
| | | |
Collapse
|
16
|
Demidenko E. An analytic solution to the homogeneous EIT problem on the 2D disk and its application to estimation of electrode contact impedances. Physiol Meas 2011; 32:1453-71. [PMID: 21799240 PMCID: PMC3183580 DOI: 10.1088/0967-3334/32/9/008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
An analytic solution of the potential distribution on a 2D homogeneous disk for electrical impedance tomography under the complete electrode model is expressed via an infinite system of linear equations. For the shunt electrode model with two electrodes, our solution coincides with the previously derived solution expressed via elliptic integral (Pidcock et al 1995 Physiol. Meas. 16 77-90). The Dirichlet-to-Neumann map is derived for statistical estimation via nonlinear least squares. The solution is validated in phantom experiments and applied for breast contact impedance estimation in vivo. Statistical hypothesis testing is used to test whether the contact impedances are the same across electrodes or all equal zero. Our solution can be especially useful for a rapid real-time test for bad surface contact in clinical setting.
Collapse
Affiliation(s)
- Eugene Demidenko
- Section of Biostatistics and Epidemiology, Dartmouth Medical School, Hanover, NH 03755, USA.
| |
Collapse
|
17
|
Demidenko E, Borsic A, Wan Y, Halter RJ, Hartov A. Statistical estimation of EIT electrode contact impedance using magic Toeplitz matrix. IEEE Trans Biomed Eng 2011; 58:10.1109/TBME.2011.2125790. [PMID: 21402505 PMCID: PMC3233639 DOI: 10.1109/tbme.2011.2125790] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The goal of the paper is to propose a fast and reliable method of simultaneous estimation of conductivity and electrode contact impedances for a homogeneous 2D disk. Magic Toeplitz matrix as the Neumann-to-Dirichlet map with finite width electrodes plays the central role in our linear model, called the gapZ model. This model enables testing of various hypotheses using the F-test, such as the uniformity of electrode impedances and their statistical significance. The gapZ model is compared with the finite element approximation, and illustrated and validated with a phantom tank experiment filled with saline. Further this model was illustrated with the patient breast EIT data to identify bad contact electrodes.
Collapse
Affiliation(s)
- Eugene Demidenko
- Section of Biostatistics and Epidemiology, Department of Mathematics, Dartmouth College, Lebanon, NH 03756 USA ()
| | - Andrea Borsic
- Thayer School of Engineering, Dartmouth College, Lebanon, NH 03756 USA
| | - Yuqing Wan
- Thayer School of Engineering, Dartmouth College, Lebanon, NH 03756 USA
| | - Ryan J. Halter
- Thayer School of Engineering, Dartmouth College, Lebanon, NH 03756 USA
| | - Alex Hartov
- Thayer School of Engineering, Dartmouth College, Lebanon, NH 03756 USA
| |
Collapse
|
18
|
Bonmassar G, Iwaki S, Goldmakher G, Angelone LM, Belliveau JW, Lev MH. On the Measurement of Electrical Impedance Spectroscopy (EIS) of the Human Head. INTERNATIONAL JOURNAL OF BIOELECTROMAGNETISM 2010; 12:32-46. [PMID: 21152370 PMCID: PMC2997709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We are introducing a system for Electrical Impedance Spectroscopy (EIS) measurements for future use in Neurological Intensive Care Unit (NICU) settings. The system consists mostly of commercially available components and the software was developed in Labview (National Instruments). The system is based on the principle that acute hemorrhagic stroke may produce detectable changes in the impedance spectrum measured on the subject's scalp due to parenchimal local increases of blood volume. EIS measurements were performed on four healthy control subjects to establish a baseline for a real time stroke detector. Measurements were performed using white noise currents in the 0-50 kHz frequency band using ten shielded electrodes placed on a subject's scalp, with electrical potentials measured with a large-dynamic range for increased EIS accuracy. EIS measurements yielded highly symmetrical impedance spectra, which was only obtainable using the proposed continuos spectral electrical impedance estimation.
Collapse
Affiliation(s)
- Giorgio Bonmassar
- AA. Martinos Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129 U.S.A
| | - Sunao Iwaki
- Life Electronics Laboratory at National Institute of Advanced Industrial Science and Technology (AIST), Osaka, Japan
| | - Gregory Goldmakher
- Emergency Neuroradiology and Neurovascular Lab, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114. U.S.A
| | - Leonardo M. Angelone
- AA. Martinos Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129 U.S.A
- Division of Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993. U.S.A
| | - John W. Belliveau
- AA. Martinos Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129 U.S.A
| | - Michael H. Lev
- Emergency Neuroradiology and Neurovascular Lab, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114. U.S.A
| |
Collapse
|