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Roth BJ. The magnetocardiogram. BIOPHYSICS REVIEWS 2024; 5:021305. [PMID: 38827563 PMCID: PMC11139488 DOI: 10.1063/5.0201950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 05/06/2024] [Indexed: 06/04/2024]
Abstract
The magnetic field produced by the heart's electrical activity is called the magnetocardiogram (MCG). The first 20 years of MCG research established most of the concepts, instrumentation, and computational algorithms in the field. Additional insights into fundamental mechanisms of biomagnetism were gained by studying isolated hearts or even isolated pieces of cardiac tissue. Much effort has gone into calculating the MCG using computer models, including solving the inverse problem of deducing the bioelectric sources from biomagnetic measurements. Recently, most magnetocardiographic research has focused on clinical applications, driven in part by new technologies to measure weak biomagnetic fields.
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Affiliation(s)
- Bradley J. Roth
- Department of Physics, Oakland University, Rochester, Michigan 48309, USA
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Khan MU, Aziz S, Iqtidar K, Fernandez-Rojas R. Computer-aided diagnosis system for cardiac disorders using variational mode decomposition and novel cepstral quinary patterns. Biomed Signal Process Control 2023. [DOI: 10.1016/j.bspc.2022.104509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Elzenheimer E, Bald C, Engelhardt E, Hoffmann J, Hayes P, Arbustini J, Bahr A, Quandt E, Höft M, Schmidt G. Quantitative Evaluation for Magnetoelectric Sensor Systems in Biomagnetic Diagnostics. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22031018. [PMID: 35161764 PMCID: PMC8838141 DOI: 10.3390/s22031018] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/21/2022] [Accepted: 01/25/2022] [Indexed: 05/19/2023]
Abstract
Dedicated research is currently being conducted on novel thin film magnetoelectric (ME) sensor concepts for medical applications. These concepts enable a contactless magnetic signal acquisition in the presence of large interference fields such as the magnetic field of the Earth and are operational at room temperature. As more and more different ME sensor concepts are accessible to medical applications, the need for comparative quality metrics significantly arises. For a medical application, both the specification of the sensor itself and the specification of the readout scheme must be considered. Therefore, from a medical user's perspective, a system consideration is better suited to specific quantitative measures that consider the sensor readout scheme as well. The corresponding sensor system evaluation should be performed in reproducible measurement conditions (e.g., magnetically, electrically and acoustically shielded environment). Within this contribution, an ME sensor system evaluation scheme will be described and discussed. The quantitative measures will be determined exemplarily for two ME sensors: a resonant ME sensor and an electrically modulated ME sensor. In addition, an application-related signal evaluation scheme will be introduced and exemplified for cardiovascular application. The utilized prototype signal is based on a magnetocardiogram (MCG), which was recorded with a superconducting quantum-interference device. As a potential figure of merit for a quantitative signal assessment, an application specific capacity (ASC) is introduced. In conclusion, this contribution highlights metrics for the quantitative characterization of ME sensor systems and their resulting output signals in biomagnetism. Finally, different ASC values and signal-to-noise ratios (SNRs) could be clearly presented for the resonant ME sensor (SNR: -90 dB, ASC: 9.8×10-7 dB Hz) and also the electrically modulated ME sensor (SNR: -11 dB, ASC: 23 dB Hz), showing that the electrically modulated ME sensor is better suited for a possible MCG application under ideal conditions. The presented approach is transferable to other magnetic sensors and applications.
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Affiliation(s)
- Eric Elzenheimer
- Digital Signal Processing and System Theory, Institute of Electrical Engineering and Information Technology, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany; (E.E.); (C.B.); (E.E.); (J.H.)
| | - Christin Bald
- Digital Signal Processing and System Theory, Institute of Electrical Engineering and Information Technology, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany; (E.E.); (C.B.); (E.E.); (J.H.)
| | - Erik Engelhardt
- Digital Signal Processing and System Theory, Institute of Electrical Engineering and Information Technology, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany; (E.E.); (C.B.); (E.E.); (J.H.)
| | - Johannes Hoffmann
- Digital Signal Processing and System Theory, Institute of Electrical Engineering and Information Technology, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany; (E.E.); (C.B.); (E.E.); (J.H.)
| | - Patrick Hayes
- Inorganic Functional Materials, Institute for Materials Science, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany; (P.H.); (E.Q.)
| | - Johan Arbustini
- Sensor System Electronics, Institute of Electrical Engineering and Information Technology, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany; (J.A.); (A.B.)
| | - Andreas Bahr
- Sensor System Electronics, Institute of Electrical Engineering and Information Technology, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany; (J.A.); (A.B.)
| | - Eckhard Quandt
- Inorganic Functional Materials, Institute for Materials Science, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany; (P.H.); (E.Q.)
| | - Michael Höft
- Microwave Engineering, Institute of Electrical Engineering and Information Technology, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany;
| | - Gerhard Schmidt
- Digital Signal Processing and System Theory, Institute of Electrical Engineering and Information Technology, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany; (E.E.); (C.B.); (E.E.); (J.H.)
- Correspondence: ; Tel.: +49-431-880-6125
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Spetzler B, Wiegand P, Durdaut P, Höft M, Bahr A, Rieger R, Faupel F. Modeling and Parallel Operation of Exchange-Biased Delta-E Effect Magnetometers for Sensor Arrays. SENSORS (BASEL, SWITZERLAND) 2021; 21:7594. [PMID: 34833678 PMCID: PMC8619412 DOI: 10.3390/s21227594] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 11/10/2021] [Accepted: 11/14/2021] [Indexed: 02/02/2023]
Abstract
Recently, Delta-E effect magnetic field sensors based on exchange-biased magnetic multilayers have shown the potential of detecting low-frequency and small-amplitude magnetic fields. Their design is compatible with microelectromechanical system technology, potentially small, and therefore, suitable for arrays with a large number N of sensor elements. In this study, we explore the prospects and limitations for improving the detection limit by averaging the output of N sensor elements operated in parallel with a single oscillator and a single amplifier to avoid additional electronics and keep the setup compact. Measurements are performed on a two-element array of exchange-biased sensor elements to validate a signal and noise model. With the model, we estimate requirements and tolerances for sensor elements using larger N. It is found that the intrinsic noise of the sensor elements can be considered uncorrelated, and the signal amplitude is improved if the resonance frequencies differ by less than approximately half the bandwidth of the resonators. Under these conditions, the averaging results in a maximum improvement in the detection limit by a factor of N. A maximum N≈200 exists, which depends on the read-out electronics and the sensor intrinsic noise. Overall, the results indicate that significant improvement in the limit of detection is possible, and a model is presented for optimizing the design of delta-E effect sensor arrays in the future.
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Affiliation(s)
- Benjamin Spetzler
- Institute of Materials Science, Faculty of Engineering, Kiel University, 24143 Kiel, Germany
| | - Patrick Wiegand
- Institute of Materials Science, Faculty of Engineering, Kiel University, 24143 Kiel, Germany
| | - Phillip Durdaut
- Institute of Materials Science, Faculty of Engineering, Kiel University, 24143 Kiel, Germany
| | - Michael Höft
- Institute of Materials Science, Faculty of Engineering, Kiel University, 24143 Kiel, Germany
| | - Andreas Bahr
- Institute of Materials Science, Faculty of Engineering, Kiel University, 24143 Kiel, Germany
| | - Robert Rieger
- Institute of Materials Science, Faculty of Engineering, Kiel University, 24143 Kiel, Germany
| | - Franz Faupel
- Institute of Materials Science, Faculty of Engineering, Kiel University, 24143 Kiel, Germany
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Yang Y, Xu M, Liang A, Yin Y, Ma X, Gao Y, Ning X. A new wearable multichannel magnetocardiogram system with a SERF atomic magnetometer array. Sci Rep 2021; 11:5564. [PMID: 33692397 PMCID: PMC7970947 DOI: 10.1038/s41598-021-84971-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 02/23/2021] [Indexed: 11/30/2022] Open
Abstract
In this study, a wearable multichannel human magnetocardiogram (MCG) system based on a spin exchange relaxation-free regime (SERF) magnetometer array is developed. The MCG system consists of a magnetically shielded device, a wearable SERF magnetometer array, and a computer for data acquisition and processing. Multichannel MCG signals from a healthy human are successfully recorded simultaneously. Independent component analysis (ICA) and empirical mode decomposition (EMD) are used to denoise MCG data. MCG imaging is realized to visualize the magnetic and current distribution around the heart. The validity of the MCG signals detected by the system is verified by electrocardiogram (ECG) signals obtained at the same position, and similar features and intervals of cardiac signal waveform appear on both MCG and ECG. Experiments show that our wearable MCG system is reliable for detecting MCG signals and can provide cardiac electromagnetic activity imaging.
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Affiliation(s)
- Yanfei Yang
- School of Instrumentation Science and Opto-Electronics Engineering, Beihang University, Beijing, 100191, China
| | - Mingzhu Xu
- School of Instrumentation Science and Opto-Electronics Engineering, Beihang University, Beijing, 100191, China
| | - Aimin Liang
- Department of Child Health Care Center, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, 100045, China
| | - Yan Yin
- School of Instrumentation Science and Opto-Electronics Engineering, Beihang University, Beijing, 100191, China
| | - Xin Ma
- Hangzhou Innovation Institute, Beihang University, Hangzhou, 310051, China.,Research Institute for Frontier Science, Beihang University, Beijing, 100191, China
| | - Yang Gao
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China.,School of Physics, Beihang University, Beijing, 100191, China
| | - Xiaolin Ning
- Hangzhou Innovation Institute, Beihang University, Hangzhou, 310051, China. .,Research Institute for Frontier Science, Beihang University, Beijing, 100191, China.
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Huang X, Hua N, Tang F, Zhang S. Effectiveness of magnetocardiography to identify patients in need of coronary artery revascularization: a cross-sectional study. Cardiovasc Diagn Ther 2020; 10:831-840. [PMID: 32968638 PMCID: PMC7487377 DOI: 10.21037/cdt-20-121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 07/09/2020] [Indexed: 07/25/2023]
Abstract
BACKGROUND Patients with angina-like symptoms need invasive or non-invasive angiography to determine whether revascularization is necessary. For patients in need of revascularization, undergoing coronary computed tomography angiography (CCTA) may delay the treatment of revascularization and increase exposure to contrast agents and radiation. The aim of this cross-sectional study was to accessed the effectiveness of magnetocardiography (MCG) to identify patients who should undergo coronary revascularization. METHODS A total of 203 patients who were suffering from angina-like symptoms and underwent percutaneous coronary angiography (PCA) between July 27, 2015 and April 10, 2017 at the 8th Medical Center of Chinese PLA General Hospital, were enrolled in this cross-sectional study. In all patients, 12-lead electrocardiography (ECG) and MCG test were performed before PCA. For each subject. The value at every single sampling point was extracted from T wave of each MCG channel in time sequence. Pearson's correlation coefficients were calculated for each two T-waves. A binary logistic regression diagnosis model of these coefficients was established to identify patients in need of revascularization. RESULTS Ten pairings of coefficients were entered into diagnostic regression model as covariates. The area under the receiver operating characteristic (ROC) curve (AUC) was 0.747 (95% CI: 0.680-0.815), and the asymptotic P value was less than 0.001. At the cut-off value of 0.55, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were 72.9%, 65.9%, 74.8%, 63.6% and 69.9%, and the positive and negative post-test probabilities were 65.9% and 25.7%. The accuracy, sensitivity, specificity, PPV and NPV for 12-lead ECG were 67.0%, 62.7%, 63.5%, 70.5% and 55.1%, respectively. However, when those acute myocardial infarction (AMI) patients were ruled out from both groups, the MCG model had an accuracy of 68.2%, a sensitivity of 70.1%, a specificity of 66.3%, a PPV of 68.5% and an NPV of 67.9%. But, the accuracy, sensitivity, specificity, PPV and NPV for 12-lead ECG were 60.0%, 55.2%, 65.1%, 62.3% and 58.1%, respectively. CONCLUSIONS Patients suffering from angina-like symptoms, with a logistic regression model value over 0.55, should be recommended for PCA.
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Affiliation(s)
- Xiao Huang
- Department of Cardiovascular, The 8th Medical Center of Chinese PLA General Hospital, Beijing, China
| | - Ning Hua
- Department of Cardiovascular, The 8th Medical Center of Chinese PLA General Hospital, Beijing, China
| | - Fakuan Tang
- Department of Cardiovascular, The 8th Medical Center of Chinese PLA General Hospital, Beijing, China
| | - Shulin Zhang
- Institute of Microsystem and Information Technology, Chinese Academy of Science, Shanghai, China
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Abstract
Here we report on designing a magnetic field sensor based on magnetoplasmonic crystal made of noble and ferromagnetic metals deposited on one-dimensional subwavelength grating. The experimental data demonstrate resonant transverse magneto-optical Kerr effect (TMOKE) at a narrow spectral region of 50 nm corresponding to the surface plasmon-polaritons excitation and maximum modulation of the reflected light intensity of 4.5% in a modulating magnetic field with the magnitude of 16 Oe. Dependences of TMOKE on external alternating current (AC) and direct current (DC) magnetic field demonstrate that it is a possibility to use the magnetoplasmonic crystal as a high-sensitive sensing probe. The achieved sensitivity to DC magnetic field is up to 10-6 Oe at local area of 1 mm2.
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Shin ES, Chung JH, Park SG, Saleh A, Lam YY, Bhak J, Jung F, Morita S, Brachmann J. Comparison of exercise electrocardiography and magnetocardiography for detection of coronary artery disease using ST-segment fluctuation score. Clin Hemorheol Microcirc 2019; 73:283-291. [DOI: 10.3233/ch-180485] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Eun-Seok Shin
- Department of Cardiology, Ulsan Medical Center, Ulsan Hospital, Ulsan, South Korea
| | - Ju-Hyun Chung
- Department of Cardiology, Ulsan Medical Center, Ulsan Hospital, Ulsan, South Korea
| | - Seung Gu Park
- Korean Genomics Industrialization and Commercialization Center (KOGIC), Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea
| | - Ahmed Saleh
- Coburg Hospital, 2nd Medical Department, Coburg, Germany
| | - Yat-Yin Lam
- Prince of Wales Hospital, Chinese University of Hong Kong, Hong Kong
| | - Jong Bhak
- Korean Genomics Industrialization and Commercialization Center (KOGIC), Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea
- Department of Biomedical Engineering, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea
| | - Friedrich Jung
- Institute of Biomaterial Science and Berlin-Brandenburg, Center for Regenerative Therapies (BCRT), Helmholtz Zentrum Geesthacht, Teltow, Germany
| | - Sumio Morita
- Department of Cardiology, Charité Campus Benjamin Franklin, Charité-Universitätsmedizin Berlin, Berlin, Germany
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Shin ES, Park SG, Saleh A, Lam YY, Bhak J, Jung F, Morita S, Brachmann J. Magnetocardiography scoring system to predict the presence of obstructive coronary artery disease. Clin Hemorheol Microcirc 2019; 70:365-373. [DOI: 10.3233/ch-189301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Eun-Seok Shin
- Division of Cardiology, Ulsan Medical Center, Ulsan Hospital, Ulsan, Korea
| | - Seung Gu Park
- Korean Genomics Industrialization and Commercialization Center (KOGIC), Ulsan National Institute of Science and Technology (UNIST), Ulsan, Korea
| | - Ahmed Saleh
- 2nd Medical Department, Coburg Hospital, Coburg, Germany
| | - Yat-Yin Lam
- Prince of Wales Hospital, Chinese University of Hong Kong, Hong Kong
| | - Jong Bhak
- Korean Genomics Industrialization and Commercialization Center (KOGIC), Ulsan National Institute of Science and Technology (UNIST), Ulsan, Korea
- Department of Biomedical Engineering, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Korea
| | - Friedrich Jung
- Institute of Biomaterial Science and Berlin-Brandenburg, Center for Regenerative Therapies (BCRT), Helmholtz Zentrum Geesthacht, Teltow, Germany
| | - Sumio Morita
- Department of Cardiology, Charité Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin, Berlin, Germany
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Ogata Y, Tanaka T, Hata Y, Kakinuma B, Ueda T, Kobayashi K. Study of Spatial Filter for Magnetocardiography Measurements without a Magnetically Shielded Room. ADVANCED BIOMEDICAL ENGINEERING 2019. [DOI: 10.14326/abe.8.170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Amirsolaimani B, Gangopadhyay P, Persoons AP, Showghi SA, LaComb LJ, Norwood RA, Peyghambarian N. High sensitivity magnetometer using nanocomposite polymers with large magneto-optic response. OPTICS LETTERS 2018; 43:4615-4618. [PMID: 30272705 DOI: 10.1364/ol.43.004615] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/14/2018] [Indexed: 06/08/2023]
Abstract
Miniaturized magnetic field sensors are increasingly used in various applications, such as geophysical exploration for minerals and oil, volcanology, earthquake studies, and biomedical imaging. Existing magnetometers lack either the spatial or the temporal resolution or are restricted to costly shielded labs and cannot operate in an unshielded environment. Increasing spatio-temporal resolution would allow for real-time measurements of magnetic fluctuations with high resolution. Here we report on a new nanocomposite-based system for miniaturized magnetic field sensing. The sensor is based on Dy3+-doped magnetite and cobalt ferrite nanoparticles dispersed in a polymer matrix. Operation is feasible at room temperature and in an unshielded environment. A compact fiber-optic interferometer is used as the detection mechanism with 20 fT/√Hz sensitivity. We investigated the magnetic field response of the sensor and demonstrated the measurement of the human heartbeat as a potential application.
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Patel R, Sengottuvel S, Gireesan K, Janawadkar MP, Radhakrishnan TS. Designing a Low-Cost, Single-Supply ECG System for Suppression of Movement Artifact from Contaminated Magnetocardiogram. SLAS Technol 2018; 23:463-469. [PMID: 29447023 DOI: 10.1177/2472630318759063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Measurement of the late potentials and His-bundle activity is crucial for many clinical studies using the noncontact and noninvasive magnetocardiography (MCG) technique; these weak signals are extracted by averaging many cardiac cycles aligned using the R-peak of the cardiac cycle identified using an electrocardiography (ECG) lead. ECG is measured simultaneously with MCG using a conventional dual-supply ECG amplifier, which requires either two separate batteries or a single battery with a switching voltage inverter circuit for its proper operation. The ECG circuitry based on two separate batteries requires a relatively large voltage supply (-18 to +18 V). The single-supply (low voltage: 0-9 V) ECG circuitry may be implemented using a switching voltage inverter; however, this mode of operation introduces switching noise in the system. The objective of the present work is to overcome these problems by carefully designing a low-voltage, single-supply ECG system, which can be used simultaneously with the MCG setup without introducing a significant level of additional noise in the MCG measurement system.
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Affiliation(s)
- Rajesh Patel
- 1 SQUIDs and Applications Section, Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, India
| | - S Sengottuvel
- 1 SQUIDs and Applications Section, Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, India
| | - K Gireesan
- 1 SQUIDs and Applications Section, Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, India
| | - M P Janawadkar
- 1 SQUIDs and Applications Section, Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, India
| | - T S Radhakrishnan
- 1 SQUIDs and Applications Section, Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, India
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Shen HM, Hu L, Fu X. Integrated Giant Magnetoresistance Technology for Approachable Weak Biomagnetic Signal Detections. SENSORS (BASEL, SWITZERLAND) 2018; 18:E148. [PMID: 29316670 PMCID: PMC5795475 DOI: 10.3390/s18010148] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 12/27/2017] [Accepted: 01/05/2018] [Indexed: 01/19/2023]
Abstract
With the extensive applications of biomagnetic signals derived from active biological tissue in both clinical diagnoses and human-computer-interaction, there is an increasing need for approachable weak biomagnetic sensing technology. The inherent merits of giant magnetoresistance (GMR) and its high integration with multiple technologies makes it possible to detect weak biomagnetic signals with micron-sized, non-cooled and low-cost sensors, considering that the magnetic field intensity attenuates rapidly with distance. This paper focuses on the state-of-art in integrated GMR technology for approachable biomagnetic sensing from the perspective of discipline fusion between them. The progress in integrated GMR to overcome the challenges in weak biomagnetic signal detection towards high resolution portable applications is addressed. The various strategies for 1/f noise reduction and sensitivity enhancement in integrated GMR technology for sub-pT biomagnetic signal recording are discussed. In this paper, we review the developments of integrated GMR technology for in vivo/vitro biomagnetic source imaging and demonstrate how integrated GMR can be utilized for biomagnetic field detection. Since the field sensitivity of integrated GMR technology is being pushed to fT/Hz0.5 with the focused efforts, it is believed that the potential of integrated GMR technology will make it preferred choice in weak biomagnetic signal detection in the future.
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Affiliation(s)
- Hui-Min Shen
- School of Mechanical Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
| | - Liang Hu
- State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310028, China.
| | - Xin Fu
- State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310028, China.
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Shin ES, Lam YY, Her AY, Brachmann J, Jung F, Park JW. Incremental diagnostic value of combined quantitative and qualitative parameters of magnetocardiography to detect coronary artery disease. Int J Cardiol 2017; 228:948-952. [PMID: 27912204 DOI: 10.1016/j.ijcard.2016.11.165] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Accepted: 11/06/2016] [Indexed: 11/25/2022]
Abstract
BACKGROUND/OBJECTIVES Magnetocardiography (MCG) has been proposed as a non-invasive and functional technique with high accuracy for diagnosis of myocardial ischemia. This study sought to investigate the incremental diagnostic value of combined quantitative and qualitative parameters of MCG to detect coronary artery disease (CAD). METHODS Ninety six patients with suspected CAD who underwent coronary angiography were enrolled in the analysis to test the diagnostic accuracy of 2 MCG parameters (a quantitative parameter of the percent change of ST-segment fluctuation score and a qualitative parameter of non-dipole phenomenon). RESULTS The best cut-off value for the percent change of ST-segment fluctuation score was -51.0%. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were 78.1, 73.9, 82.0, 79.1, and 77.4, in the percent change of ST-segment fluctuation score and 86.5, 84.8, 88.0, 86.7, and 86.3 in non-dipole phenomenon. The area under the curve of receiver-operating characteristics was 0.79 for the percent change of ST-segment fluctuation score and 0.86 for non-dipole phenomenon (p<0.001). However, the incorporation of non-dipole phenomenon into a model with the percent change of ST-segment fluctuation score significantly improved C-statistics, indicating the enhancement of diagnostic performance in the detection of significant CAD (0.790 to 0.930; p<0.001). CONCLUSIONS Qualitative assessment of non-dipole phenomenon has a better diagnostic value than the quantitative parameter of percent change of ST-segment fluctuation score in the detection of significant CAD. Furthermore, this study found that the incorporation of non-dipole phenomenon into the percent change of ST-segment fluctuation score significantly improved the diagnostic performance of CAD detection.
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Affiliation(s)
- Eun-Seok Shin
- Department of Cardiology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, South Korea
| | - Yat-Yin Lam
- Prince of Wales Hospital, Chinese University of Hong Kong, Hong Kong
| | - Ae-Young Her
- Division of Cardiology, Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, South Korea
| | | | - Friedrich Jung
- Institute of Biomaterial Science and Berlin-Brandenburg, Center for Regenerative Therapies (BCRT), Helmholtz Zentrum Geesthacht, Teltow, Germany
| | - Jai-Wun Park
- Coburg Hospital, 2nd Medical Department, Coburg, Germany.
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Colombo AP, Carter TR, Borna A, Jau YY, Johnson CN, Dagel AL, Schwindt PDD. Four-channel optically pumped atomic magnetometer for magnetoencephalography. OPTICS EXPRESS 2016; 24:15403-16. [PMID: 27410816 PMCID: PMC5025229 DOI: 10.1364/oe.24.015403] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We have developed a four-channel optically pumped atomic magnetometer for magnetoencephalography (MEG) that incorporates a passive diffractive optical element (DOE). The DOE allows us to achieve a long, 18-mm gradiometer baseline in a compact footprint on the head. Using gradiometry, the sensitivities of the channels are < 5 fT/Hz1/2, and the 3-dB bandwidths are approximately 90 Hz, which are both sufficient to perform MEG. Additionally, the channels are highly uniform, which offers the possibility of employing standard MEG post-processing techniques. This module will serve as a building block of an array for magnetic source localization.
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Affiliation(s)
| | - Tony R. Carter
- Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185,
USA
| | - Amir Borna
- Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185,
USA
| | - Yuan-Yu Jau
- Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185,
USA
| | - Cort N. Johnson
- Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185,
USA
- Currently with the Charles Stark Draper Laboratory, 555 Technology Square, Cambridge, MA 02139,
USA
| | - Amber L. Dagel
- Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185,
USA
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Shin ES, Ann SH, Brachmann J, Lam YY, Jung F, Park JW. Noninvasive detection of myocardial ischemia: a case of magnetocardiography. Clin Hemorheol Microcirc 2015; 60:163-9. [PMID: 26409321 DOI: 10.3233/ch-151945] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Eun-Seok Shin
- Department of Cardiology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea
| | - Soe Hee Ann
- Department of Cardiology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea
| | | | - Yat-Yin Lam
- Prince of Wales Hospital, Chinese University of Hong Kong, Hong Kong
| | - Friedrich Jung
- Institute for Clinical Hemostasiology and Transfusion Medicine, Saarland University, Homburg/Saar, Germany
| | - Jai-Wun Park
- Department of Cardiology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea
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18
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Mariyappa N, Sengottuvel S, Rajesh Patel, Parasakthi C, Gireesan K, Janawadkar M, Radhakrishnan T, Sundar C. Denoising of multichannel MCG data by the combination of EEMD and ICA and its effect on the pseudo current density maps. Biomed Signal Process Control 2015. [DOI: 10.1016/j.bspc.2014.12.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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19
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Nakayama S, Uchiyama T. Real-time measurement of biomagnetic vector fields in functional syncytium using amorphous metal. Sci Rep 2015; 5:8837. [PMID: 25744476 DOI: 10.1038/srep08837] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 02/06/2015] [Indexed: 11/09/2022] Open
Abstract
Magnetic field detection of biological electric activities would provide a non-invasive and aseptic estimate of the functional state of cellular organization, namely a syncytium constructed with cell-to-cell electric coupling. In this study, we investigated the properties of biomagnetic waves which occur spontaneously in gut musculature as a typical functional syncytium, by applying an amorphous metal-based gradio-magneto sensor operated at ambient temperature without a magnetic shield. The performance of differentiation was improved by using a single amorphous wire with a pair of transducer coils. Biomagnetic waves of up to several nT were recorded ~1 mm below the sample in a real-time manner. Tetraethyl ammonium (TEA) facilitated magnetic waves reflected electric activity in smooth muscle. The direction of magnetic waves altered depending on the relative angle of the muscle layer and magneto sensor, indicating the existence of propagating intercellular currents. The magnitude of magnetic waves rapidly decreased to ~30% by the initial and subsequent 1 mm separations between sample and sensor. The large distance effect was attributed to the feature of bioelectric circuits constructed by two reverse currents separated by a small distance. This study provides a method for detecting characteristic features of biomagnetic fields arising from a syncytial current.
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Affiliation(s)
- Shinsuke Nakayama
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Tusyoshi Uchiyama
- Department of Electronics, Nagoya University of Graduate School of Engineering, Nagoya 464-8603, Japan
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20
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Mariyappa N, Sengottuvel S, Parasakthi C, Gireesan K, Janawadkar MP, Radhakrishnan TS, Sundar CS. Baseline drift removal and denoising of MCG data using EEMD: role of noise amplitude and the thresholding effect. Med Eng Phys 2014; 36:1266-76. [PMID: 25074650 DOI: 10.1016/j.medengphy.2014.06.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Revised: 05/14/2014] [Accepted: 06/29/2014] [Indexed: 10/25/2022]
Abstract
We adopt the Ensemble Empirical Mode Decomposition (EEMD) method, with an appropriate thresholding on the Intrinsic Mode Functions (IMFs), to denoise the magnetocardiography (MCG) signal. To this end, we discuss the two associated problems that relate to: (i) the amplitude of noise added to the observed signal in the EEMD method with a view to prevent mode mixing and (ii) the effect of direct thresholding that causes discontinuities in the reconstructed denoised signal. We then denoise the MCG signals, having various signal-to-noise ratios, by using this method and compare the results with those obtained by the standard wavelet based denoising method. We also address the problem of eliminating the high frequency baseline drift such as the sudden and discontinuous changes in the baseline of the experimentally measured MCG signal using the EEMD based method. We show that the EEMD method used for denoising and the elimination of baseline drift is superior in performance to other standard methods such as wavelet based techniques and Independent Component Analysis (ICA).
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Affiliation(s)
- N Mariyappa
- Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India.
| | - S Sengottuvel
- Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
| | - C Parasakthi
- Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
| | - K Gireesan
- Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
| | - M P Janawadkar
- Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
| | - T S Radhakrishnan
- Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
| | - C S Sundar
- Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
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21
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Abstract
Magnetocardiography is a noninvasive contactless method to measure the magnetic field generated by the same ionic currents that create the electrocardiogram. The time course of magnetocardiographic and electrocardiographic signals are similar. However, compared with surface potential recordings, multichannel magnetocardiographic mapping (MMCG) is a faster and contactless method for 3D imaging and localization of cardiac electrophysiologic phenomena with higher spatial and temporal resolution. For more than a decade, MMCG has been mostly confined to magnetically shielded rooms and considered to be at most an interesting matter for research activity. Nevertheless, an increasing number of papers have documented that magnetocardiography can also be useful to improve diagnostic accuracy. Most recently, the development of standardized instrumentations for unshielded MMCG, and its ease of use and reliability even in emergency rooms has triggered a new interest from clinicians for magnetocardiography, leading to several new installations of unshielded systems worldwide. In this review, clinical applications of magnetocardiography are summarized, focusing on major milestones, recent results of multicenter clinical trials and indicators of future developments.
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Affiliation(s)
- Riccardo Fenici
- Clinical Physiology - Biomagnetism Center, Catholic University of Sacred Heart, Rome, Italy.
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22
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Johnson CN, Schwindt PDD, Weisend M. Multi-sensor magnetoencephalography with atomic magnetometers. Phys Med Biol 2013; 58:6065-77. [PMID: 23939051 DOI: 10.1088/0031-9155/58/17/6065] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The authors have detected magnetic fields from the human brain with two independent, simultaneously operating rubidium spin-exchange-relaxation-free magnetometers. Evoked responses from auditory stimulation were recorded from multiple subjects with two multi-channel magnetometers located on opposite sides of the head. Signal processing techniques enabled by multi-channel measurements were used to improve signal quality. This is the first demonstration of multi-sensor atomic magnetometer magnetoencephalography and provides a framework for developing a non-cryogenic, whole-head magnetoencephalography array for source localization.
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Affiliation(s)
- Cort N Johnson
- Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185-1082, USA.
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23
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Uchiyama T, Nakayama S. Magnetic sensors using amorphous metal materials: detection of premature ventricular magnetic waves. Physiol Rep 2013; 1:e00030. [PMID: 24303116 PMCID: PMC3831925 DOI: 10.1002/phy2.30] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 06/13/2013] [Accepted: 06/14/2013] [Indexed: 11/07/2022] Open
Abstract
The detection of magnetic activity enables noncontact and noninvasive evaluation of electrical activity in humans. We review the detection of biomagnetic fields using amorphous metal wire-based magnetic sensors with the sensitivity of a pico-Tesla (pT) level. We measured magnetic fields close to the thoracic wall in a healthy subject sitting on a chair. The magnetic sensor head was mounted perpendicularly against the thoracic wall. Simultaneous measurements with ECG showed that changes in the magnetic field were synchronized with the cardiac electric activity, and that the magnetic wave pattern changed reflecting electrical activity of the atrium and ventricle, despite a large variation. Furthermore, magnetic waves reflecting ventricular arrhythmia were recorded in the same healthy subject. These results suggest that this magnetic sensor technology is applicable to human physiology and pathophysiology research. We also discuss future applications of amorphous wire-based magnetic sensors as well as possible improvements.
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Affiliation(s)
- Tsuyoshi Uchiyama
- Department of Electronics, Nagoya University of Graduate School of Engineering Nagoya, 464-8603, Japan
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24
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Dominguez-Nicolas SM, Juarez-Aguirre R, Herrera-May AL, Garcia-Ramirez P, Figueras E, Gutierrez-D EA, Tapia JA, Trejo A, Manjarrez E. Respiratory magnetogram detected with a MEMS device. Int J Med Sci 2013; 10:1445-50. [PMID: 24046516 PMCID: PMC3775099 DOI: 10.7150/ijms.4732] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 11/26/2012] [Indexed: 11/28/2022] Open
Abstract
Magnetic fields generated by the brain or the heart are very useful in clinical diagnostics. Therefore, magnetic signals produced by other organs are also of considerable interest. Here we show first evidence that thoracic muscles can produce a strong magnetic flux density during respiratory activity, that we name respiratory magnetogram. We used a small magnetometer based on microelectromechanical systems (MEMS), which was positioned inside the open thoracic cage of anaesthetized and ventilated rats. With this new MEMS sensor of about 20 nT resolution, we recorded a strong and rhythmic respiratory magnetogram of about 600 nT.
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Affiliation(s)
- Saul M Dominguez-Nicolas
- 1. Research Center for Micro and Nano Technology, Universidad Veracruzana, Calzada Adolfo Ruíz Cortines 455, 94294, Boca del Río, Ver., Mexico
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25
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Nakayama S, Sawamura K, Mohri K, Uchiyama T. Pulse-driven magnetoimpedance sensor detection of cardiac magnetic activity. PLoS One 2011; 6:e25834. [PMID: 22022453 PMCID: PMC3192116 DOI: 10.1371/journal.pone.0025834] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 09/12/2011] [Indexed: 11/19/2022] Open
Abstract
This study sought to establish a convenient method for detecting biomagnetic activity in the heart. Electrical activity of the heart simultaneously induces a magnetic field. Detection of this magnetic activity will enable non-contact, noninvasive evaluation to be made. We improved the sensitivity of a pulse-driven magnetoimpedance (PMI) sensor, which is used as an electric compass in mobile phones and as a motion sensor of the operation handle in computer games, toward a pico-Tesla (pT) level, and measured magnetic fields on the surface of the thoracic wall in humans. The changes in magnetic field detected by this sensor synchronized with the electric activity of the electrocardiogram (ECG). The shape of the magnetic wave was largely altered by shifting the sensor position within 20 mm in parallel and/or perpendicular to the thoracic wall. The magnetic activity was maximal in the 4th intercostals near the center of the sterna. Furthermore, averaging the magnetic activity at 15 mm in the distance between the thoracic wall and the sensor demonstrated magnetic waves mimicking the P wave and QRS complex. The present study shows the application of PMI sensor in detecting cardiac magnetic activity in several healthy subjects, and suggests future applications of this technology in medicine and biology.
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Affiliation(s)
- Shinsuke Nakayama
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kenta Sawamura
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kaneo Mohri
- Department of Electronics, Nagoya University of Graduate School of Engineering, Nagoya, Japan
| | - Tsuyoshi Uchiyama
- Department of Electronics, Nagoya University of Graduate School of Engineering, Nagoya, Japan
- * E-mail:
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26
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Nakayama S, Atsuta S, Shinmi T, Uchiyama T. Pulse-driven magnetoimpedance sensor detection of biomagnetic fields in musculatures with spontaneous electric activity. Biosens Bioelectron 2011; 27:34-9. [PMID: 21741817 DOI: 10.1016/j.bios.2011.05.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2011] [Revised: 05/26/2011] [Accepted: 05/26/2011] [Indexed: 01/22/2023]
Abstract
We measured biomagnetic fields in musculatures with spontaneous electric activity using a pulse-driven magnetoimpedance (PMI) sensor with the sensitivity improved toward a pico-Tesla (pT) level. Due to the sufficiently short operation interval of 1 μs, this magnetic sensor enabled quasi-real time recordings of the magnetic field for biological electric activity. Isolated small musculatures from the guinea-pig stomach, taenia caeci, portal vein and urinary bladder were incubated in an organ bath at a body temperature. The improved PMI sensor mounted approximately 1mm below the preparations detected oscillatory magnetic fields reflecting spontaneous electric activities of musculature preparations. In the taenia caeci, application of tetraethyl ammonium (TEA), a K(+) channel blocker, significantly enhanced the magnetic activity estimated by histogram analysis. Also, in some musculature preparations, simultaneous measurements with electric activity revealed that the observed magnetic activities were attributed to biological electric activity. PMI technology is promising for applications in biology and medicine.
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Affiliation(s)
- Shinsuke Nakayama
- Department of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
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27
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Bradshaw LA, Cheng LK, Richards WO, Pullan AJ. Surface current density mapping for identification of gastric slow wave propagation. IEEE Trans Biomed Eng 2009; 56:2131-9. [PMID: 19403355 DOI: 10.1109/tbme.2009.2021576] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The magnetogastrogram (MGG) records clinically relevant parameters of the electrical slow wave of the stomach noninvasively. Besides slow wave frequency, gastric slow wave propagation velocity is a potentially useful clinical indicator of the state of health of gastric tissue, but it is a difficult parameter to determine from noninvasive bioelectric or biomagnetic measurements. We present a method for computing the surface current density from multichannel MGG recordings that allows computation of the propagation velocity of the gastric slow wave. A moving dipole source model with hypothetical as well as realistic biomagnetometer parameters demonstrates that while a relatively sparse array of magnetometer sensors is sufficient to compute a single average propagation velocity, more detailed information about spatial variations in propagation velocity requires higher density magnetometer arrays. Finally, the method is validated with simultaneous MGG and serosal electromyography measurements in a porcine subject.
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Affiliation(s)
- L Alan Bradshaw
- Department of Surgery, Vanderbilt University, Nashville, TN 37235 USA.
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28
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Lim HK, Kwon H, Chung N, Ko YG, Kim JM, Kim IS, Park YK. Usefulness of magnetocardiogram to detect unstable angina pectoris and non-ST elevation myocardial infarction. Am J Cardiol 2009; 103:448-54. [PMID: 19195500 DOI: 10.1016/j.amjcard.2008.10.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Revised: 10/13/2008] [Accepted: 10/13/2008] [Indexed: 11/28/2022]
Abstract
Electrophysiologic information as well as anatomic information to detect coronary artery disease is important for accurate diagnosis. A diagnostic tool that can detect patients with unstable angina pectoris (UAP) or non-ST elevation myocardial infarction (NSTEMI) with severe stenosis would be beneficial for patients and clinicians. Magnetocardiography has been recognized as a noncontact, noninvasive, fast tool to detect ischemic coronary artery disease and provide direct electrophysiologic information from the heart. In this study, 10 magnetocardiographic (MCG) parameters from 4 groups, including 185 young controls, 19 age-matched controls (AMCs), 110 patients with UAP, and 83 patients with NSTEMIs, were analyzed. A 64-channel MCG system in a magnetically shielded room was used. All 10 parameters showed significant differences (p <0.001) between controls and patients with NSTEMIs, and 6 parameters showed significant differences (p <0.01) between AMCs and patients with UAP. MCG parameters significantly increased when ischemic heart conditions worsened. Of the 10 parameters, the magnetic field map was among the easiest ways to detect the severity of coronary artery disease. Abnormal magnetic field maps were observed frequently with worsening ischemic coronary artery disease (70% of patients with UAP and 92.5% of those with NSTEMIs had abnormal maps). The combination of the binary boundaries of the 10 parameters had 96.4% sensitivity and 85% specificity to detect NSTEMI. In conclusion, the MCG parameters and magnetic field maps may detect UAP and NSTEMI easily when they are considered together.
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Affiliation(s)
- Hyun Kyoon Lim
- Korea Research Institute of Standards and Science, Daejeon, Korea.
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29
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Kyoon Lim H, Kim K, Lee YH, Chung N. Detection of non-ST-elevation myocardial infarction using magnetocardiogram: new information from spatiotemporal electrical activation map. Ann Med 2009; 41:533-46. [PMID: 19626486 DOI: 10.1080/07853890903107883] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
BACKGROUND AND AIM Non-ST-segment elevation myocardial infarction (NSTEMI) cannot be easily detected in the emergency room. We evaluate a method to detect NSTEMI using 64-channel magnetocardiography (MCG). METHODS MCG recordings were made in 20 NSTEMI patients (aged 59.7+/-12.4 years), 15 young (aged 26.8+/-3.4 years), and 13 age-matched control subjects (aged 57.3+/-3.6). We evaluated three approaches to analysis, including 1) determination when individual subjects' MCG results fell outside normal ranges for ten MCG parameters, 2) the magnetic field map at the T-wave peak (T-MFM), and 3) a pair of spatiotemporal activation graphs (STAGs) showing two projections of electrical excitation during repolarization. RESULTS Significant differences were found between normal controls and patients for all MCG parameters. None of the healthy controls had more than four MCG abnormal parameters, whereas 19 NSTEMI patients (95%) were abnormal in more than four parameters. STAGs and T-MFM also showed clear differences between healthy controls and NSTEMI patients. CONCLUSIONS These results suggest that the MCG is sensitive to changes in the cardiac electrical pathway after myocardial infarction as described by these graphs and parameters, and therefore MCG may be a useful tool to detect severe ischemic patients.
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Affiliation(s)
- Hyun Kyoon Lim
- Korea Research Institute of Standards and Science, Daejeon, Korea
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30
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Fenici R, Brisinda D. From 3D to 4D imaging: is that useful for interventional cardiac electrophysiology? ACTA ACUST UNITED AC 2008; 2007:5996-9. [PMID: 18003380 DOI: 10.1109/iembs.2007.4353714] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Three-dimensional electroanatomical imaging is increasingly used in interventional cardiac electrophysiology, to guide catheter ablation of cardiac arrhythmias. At the same time, there is a growing interest for non-invasive methods, such as magnetocardiographic mapping (MCG), to localize the arrhythmogenic substrates, to test their reproducibility and to plan the most appropriate interventional approach. So far electroanatomical imaging has relayed on static mathematical modeling of the heart and more recently on direct merging with three-dimensional rendering of cardiac anatomy from multidetector computer tomography or magnetic resonance imaging. Merging electrophysiological information with static anatomical structures, can surely be a source of uncertainty for MCG-based pre-interventional localization of the arrhythmogenic substrate and causes mismatch between the real-time imaging of moving catheters and the static geometry of the cardiac chambers reconstructed with invasive electroanatomical imaging. The implementation of recent realistic numerical models of the beating heart in a breathing thorax can improve accuracy and fill the gap between non-invasive and interventional electroanatomical imaging.
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Affiliation(s)
- R Fenici
- Clinical Physiology - Biomagnetism Research Center, Catholic University of Sacred Heart, Largo A. Gemelli 8, 00168 Rome, Italy
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31
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Gapelyuk A, Wessel N, Fischer R, Zacharzowsky U, Koch L, Selbig D, Schütt H, Sawitzki B, Luft FC, Dietz R, Schirdewan A. Detection of patients with coronary artery disease using cardiac magnetic field mapping at rest. J Electrocardiol 2007; 40:401-7. [PMID: 17531250 DOI: 10.1016/j.jelectrocard.2007.03.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2006] [Accepted: 03/01/2007] [Indexed: 10/23/2022]
Abstract
We studied the use of cardiac magnetic field mapping to detect patients with CAD without subjecting them to stress. Fifty-nine healthy control subjects and 101 patients with CAD without previous MI were included. The optimal positions for detecting CAD were located in the left superior parasternal and in the inferior midsternal area. Values for ST slope, ST shift, T peak amplitude, ST-T integral, and magnetic field map orientation differed significantly between the 2 groups. Three parameters together in a multivariate analysis yielded a sensitivity of 84% and a specificity of 83% in distinguishing patients with CAD from control subjects. We suggest that cardiac magnetic field mapping is a promising technique to identify patients with CAD.
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Affiliation(s)
- Andrej Gapelyuk
- Medical Faculty of the Charité, Franz Volhard Klinik, Helios Klinikum-Berlin, Berlin, Germany
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Abstract
Abstract. There are a wide range of sensors for acquiring signals from the human body in noninvasive ways. Some of those in use date back a few decades, and many new technologies have enabled different sensors designs in recent years. This review covers the following classes of sensors: electric, magnetic, electrochemical, mechanical, thermal, and optical. Sensor systems that are portable, safe, and low-cost are now becoming possible. This review provides an overview focussing on the technology behind sensors currently used by psychophysiologists with the objective of illuminating the choices available for acquiring signals that inform us about cognitive processes, emotional states, and behavioural patterns. In previously published encyclopaedic-type reviews of psychophysiology, the focus has been on what is measured, not how it is measured. By focussing on how the sensors and sensor systems work, this review aims to provide users of these technologies with information that will help them decide on the appropriate sensor to use, as well as to facilitate innovation and development of new sensors.
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Affiliation(s)
- Tim R.H. Cutmore
- School of Psychology, Griffith University, Brisbane, Queensland, Australia
| | - Daniel A. James
- School of Micro-Electronics Engineering, Griffith University, Brisbane, Queensland, Australia
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33
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Fenici R, Brisinda D. Bridging noninvasive and interventional electroanatomical imaging: role of magnetocardiography. J Electrocardiol 2007. [DOI: 10.1016/j.jelectrocard.2006.10.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Haberkorn W, Steinhoff U, Burghoff M, Kosch O, Morguet A, Koch H. Pseudo current density maps of electrophysiological heart, nerve or brain function and their physical basis. BIOMAGNETIC RESEARCH AND TECHNOLOGY 2006; 4:5. [PMID: 17040559 PMCID: PMC1660567 DOI: 10.1186/1477-044x-4-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Accepted: 10/13/2006] [Indexed: 01/30/2023]
Abstract
Background In recent years the visualization of biomagnetic measurement data by so-called pseudo current density maps or Hosaka-Cohen (HC) transformations became popular. Methods The physical basis of these intuitive maps is clarified by means of analytically solvable problems. Results Examples in magnetocardiography, magnetoencephalography and magnetoneurography demonstrate the usefulness of this method. Conclusion Hardware realizations of the HC-transformation and some similar transformations are discussed which could advantageously support cross-platform comparability of biomagnetic measurements.
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Affiliation(s)
| | - Uwe Steinhoff
- Physikalisch-Technische Bundesanstalt, Berlin, Germany
| | | | - Olaf Kosch
- Physikalisch-Technische Bundesanstalt, Berlin, Germany
| | - Andreas Morguet
- Charité Campus Benjamin Franklin, Clinic II, Berlin, Germany
| | - Hans Koch
- Physikalisch-Technische Bundesanstalt, Berlin, Germany
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35
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Brisinda D, Caristo ME, Fenici R. Contactless magnetocardiographic mapping in anesthetized Wistar rats: evidence of age-related changes of cardiac electrical activity. Am J Physiol Heart Circ Physiol 2006; 291:H368-78. [PMID: 16373584 DOI: 10.1152/ajpheart.01048.2005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Magnetocardiography (MCG) is the recording of the magnetic field (MF) generated by cardiac electrophysiological activity. Because it is a contactless method, MCG is ideal for noninvasive cardiac mapping of small experimental animals. The aim of this study was to assess age-related changes of cardiac intervals and ventricular repolarization (VR) maps in intact rats by means of MCG mapping. Twenty-four adult Wistar rats (12 male and 12 female) were studied, under anesthesia, with the same unshielded 36-channel MCG instrumentation used for clinical recordings. Two sets of measurements were obtained from each animal: 1) at 5 mo of age (297.5 ± 21 g body wt) and 2) at 14 mo of age (516.8 ± 180 g body wt). RR and PR intervals, QRS segment, and QTpeak, QTend, JTpeak, JTend, and Tpeak-end were measured from MCG waveforms. MCG imaging was automatically obtained as MF maps and as inverse localization of cardiac sources with equivalent current dipole and effective magnetic dipole models. After 300 s of continuous recording were averaged, the signal-to-noise ratio was adequate for study of atrial and ventricular MF maps and for three-dimensional localization of the underlying cardiac sources. Clear-cut age-related differences in VR duration were demonstrated by significantly longer QTend, JTend, and Tpeak-end in older Wistar rats. Reproducible multisite noninvasive cardiac mapping of anesthetized rats is simpler with MCG methodology than with ECG recording. In addition, MCG mapping provides new information based on quantitative analysis of MF and equivalent sources. In this study, statistically significant age-dependent variations in VR intervals were found.
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Affiliation(s)
- Donatella Brisinda
- Biomagnetism Center, Clinical Physiology, Catholic University of the Sacred Heart, Rome, Italy
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