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Kesavaraja C, Sengottuvel S, Patel R, Selvaraj RJ, Satheesh S, Mani A. Enhancing the efficiency and cost-effectiveness of magnetocardiography by optimal channel selection for cardiac diagnosis. Biomed Phys Eng Express 2024; 10:025023. [PMID: 38277702 DOI: 10.1088/2057-1976/ad233e] [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: 11/01/2023] [Accepted: 01/26/2024] [Indexed: 01/28/2024]
Abstract
Background. Magnetocardiography (MCG) is a non-invasive and non-contact technique that measures weak magnetic fields generated by the heart. It is highly effective in the diagnosis of heart abnormalities. Multichannel MCG provides detailed spatio-temporal information of the measured magnetic fields. While multichannel MCG systems are costly, usage of the optimal number of measurement channels to characterize cardiac magnetic fields without any appreciable loss of signal information would be economically beneficial and promote the widespread use of MCG technology.Methods. An optimization method based on the sequential selection approach is used to choose channels containing the maximum signal information while avoiding redundancy. The study comprised 40 healthy individuals, along with two subjects having ischemic heart disease and one subject with premature ventricular contraction. MCG measured using a 37 channel MCG system. After revisiting the existing methods of optimization, the mean error and correlation of the optimal set of measurement channels with those of all 37 channels are evaluated for different sets, and it has been found that 18 channels are adequate.Results. The chosen 18 optimal channels exhibited a strong correlation (0.99 ± 0.006) between the original and reconstructed magnetic field maps for a cardiac cycle in healthy subjects. The root mean square error is 0.295 pT, indicating minimal deviation.Conclusion. This selection method provides an efficient approach for choosing MCG, which could be used for minimizing the number of channels as well as in practical unforeseen measurement conditions where few channels are noisy during the measurement.
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Affiliation(s)
- C Kesavaraja
- Indira Gandhi Centre for Atomic Research, A CI of Homi Bhabha National Institute, Kalpakkam-603102, Tamil Nadu, India
| | - S Sengottuvel
- SQUIDs Applications section, SQUID & Detector Technology Division, Materials Science Group, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam-603102, Tamil Nadu, India
| | - Rajesh Patel
- SQUIDs Applications section, SQUID & Detector Technology Division, Materials Science Group, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam-603102, Tamil Nadu, India
| | - Raja J Selvaraj
- Department of Cardiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry-605006, India
| | - Santhosh Satheesh
- Department of Cardiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry-605006, India
| | - Awadhesh Mani
- Indira Gandhi Centre for Atomic Research, A CI of Homi Bhabha National Institute, Kalpakkam-603102, Tamil Nadu, India
- Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam-603102, Tamil Nadu, India
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Karittevlis C, Papadopoulos M, Lima V, Orphanides GA, Tiwari S, Antonakakis M, Papadopoulou Lesta V, Ioannides AA. First activity and interactions in thalamus and cortex using raw single-trial EEG and MEG elicited by somatosensory stimulation. Front Syst Neurosci 2024; 17:1305022. [PMID: 38250330 PMCID: PMC10797085 DOI: 10.3389/fnsys.2023.1305022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 12/06/2023] [Indexed: 01/23/2024] Open
Abstract
Introduction One of the primary motivations for studying the human brain is to comprehend how external sensory input is processed and ultimately perceived by the brain. A good understanding of these processes can promote the identification of biomarkers for the diagnosis of various neurological disorders; it can also provide ways of evaluating therapeutic techniques. In this work, we seek the minimal requirements for identifying key stages of activity in the brain elicited by median nerve stimulation. Methods We have used a priori knowledge and applied a simple, linear, spatial filter on the electroencephalography and magnetoencephalography signals to identify the early responses in the thalamus and cortex evoked by short electrical stimulation of the median nerve at the wrist. The spatial filter is defined first from the average EEG and MEG signals and then refined using consistency selection rules across ST. The refined spatial filter is then applied to extract the timecourses of each ST in each targeted generator. These ST timecourses are studied through clustering to quantify the ST variability. The nature of ST connectivity between thalamic and cortical generators is then studied within each identified cluster using linear and non-linear algorithms with time delays to extract linked and directional activities. A novel combination of linear and non-linear methods provides in addition discrimination of influences as excitatory or inhibitory. Results Our method identifies two key aspects of the evoked response. Firstly, the early onset of activity in the thalamus and the somatosensory cortex, known as the P14 and P20 in EEG and the second M20 for MEG. Secondly, good estimates are obtained for the early timecourse of activity from these two areas. The results confirm the existence of variability in ST brain activations and reveal distinct and novel patterns of connectivity in different clusters. Discussion It has been demonstrated that we can extract new insights into stimulus processing without the use of computationally costly source reconstruction techniques which require assumptions and detailed modeling of the brain. Our methodology, thanks to its simplicity and minimal computational requirements, has the potential for real-time applications such as in neurofeedback systems and brain-computer interfaces.
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Affiliation(s)
- Christodoulos Karittevlis
- AAI Scientific Cultural Services Ltd., Nicosia, Cyprus
- Department of Computer Science, European University Cyprus, Nicosia, Cyprus
| | | | - Vinicius Lima
- Aix Marseille Université, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
| | - Gregoris A. Orphanides
- AAI Scientific Cultural Services Ltd., Nicosia, Cyprus
- Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Shubham Tiwari
- Department of Geography, Durham University, Durham, United Kingdom
| | - Marios Antonakakis
- School of Electrical and Computer Engineering, Technical University of Crete, Chania, Greece
- Institute for Biomagnetism and Biosignal Analysis, Medicine Faculty, University of Münster, Münster, Germany
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Engelhardt E, Elzenheimer E, Hoffmann J, Meledeth C, Frey N, Schmidt G. Non-Invasive Electroanatomical Mapping: A State-Space Approach for Myocardial Current Density Estimation. Bioengineering (Basel) 2023; 10:1432. [PMID: 38136023 PMCID: PMC10741003 DOI: 10.3390/bioengineering10121432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 12/05/2023] [Accepted: 12/13/2023] [Indexed: 12/24/2023] Open
Abstract
Electroanatomical mapping is a method for creating a model of the electrophysiology of the human heart. Medical professionals routinely locate and ablate the site of origin of cardiac arrhythmias with invasive catheterization. Non-invasive localization takes the form of electrocardiographic (ECG) or magnetocardiographic (MCG) imaging, where the goal is to reconstruct the electrical activity of the human heart. Non-invasive alternatives to catheter electroanatomical mapping would reduce patients' risks and open new venues for treatment planning and prevention. This work introduces a new system state-based method for estimating the electrical activity of the human heart from MCG measurements. Our model enables arbitrary propagation paths and velocities. A Kalman filter optimally estimates the current densities under the given measurements and model parameters. In an outer optimization loop, these model parameters are then optimized via gradient descent. This paper aims to establish the foundation for future research by providing a detailed mathematical explanation of the algorithm. We demonstrate the feasibility of our method through a simplified one-layer simulation. Our results show that the algorithm can learn the propagation paths from the magnetic measurements. A threshold-based segmentation into healthy and pathological tissue yields a DICE score of 0.84, a recall of 0.77, and a precision of 0.93.
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Affiliation(s)
- Erik Engelhardt
- Department of Electrical Information Engineering, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany; (E.E.); (E.E.)
| | - Eric Elzenheimer
- Department of Electrical Information Engineering, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany; (E.E.); (E.E.)
| | - Johannes Hoffmann
- Department of Electrical Information Engineering, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany; (E.E.); (E.E.)
| | - Christy Meledeth
- Internal Medicine 1—Cardiology and Internal Intensive Care Medicine, Med Campus III, Kepler University Hospital, Krankenhausstraße 9, 4021 Linz, Austria;
| | - Norbert Frey
- Department of Internal Medicine III (Cardiology, Angiology and Pneumonology), University Medical Center Heidelberg, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany;
| | - Gerhard Schmidt
- Department of Electrical Information Engineering, Faculty of Engineering, Kiel University, Kaiserstr. 2, 24143 Kiel, Germany; (E.E.); (E.E.)
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Han X, Pang J, Xu D, Wang R, Xie F, Yang Y, Sun J, Li Y, Li R, Yin X, Xu Y, Fan J, Dong Y, Wu X, Yang X, Yu D, Wang D, Gao Y, Xiang M, Xu F, Sun J, Chen Y, Ning X. Magnetocardiography-based coronary artery disease severity assessment and localization using spatiotemporal features. Physiol Meas 2023; 44:125002. [PMID: 37995382 DOI: 10.1088/1361-6579/ad0f70] [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: 10/10/2023] [Accepted: 11/23/2023] [Indexed: 11/25/2023]
Abstract
Objective.This study aimed to develop an automatic and accurate method for severity assessment and localization of coronary artery disease (CAD) based on an optically pumped magnetometer magnetocardiography (MCG) system.Approach.We proposed spatiotemporal features based on the MCG one-dimensional signals, including amplitude, correlation, local binary pattern, and shape features. To estimate the severity of CAD, we classified the stenosis as absence or mild, moderate, or severe cases and extracted a subset of features suitable for assessment. To localize CAD, we classified CAD groups according to the location of the stenosis, including the left anterior descending artery (LAD), left circumflex artery (LCX), and right coronary artery (RCA), and separately extracted a subset of features suitable for determining the three CAD locations.Main results.For CAD severity assessment, a support vector machine (SVM) achieved the best result, with an accuracy of 75.1%, precision of 73.9%, sensitivity of 67.0%, specificity of 88.8%, F1-score of 69.8%, and area under the curve of 0.876. The highest accuracy and corresponding model for determining locations LAD, LCX, and RCA were 94.3% for the SVM, 84.4% for a discriminant analysis model, and 84.9% for the discriminant analysis model.Significance. The developed method enables the implementation of an automated system for severity assessment and localization of CAD. The amplitude and correlation features were key factors for severity assessment and localization. The proposed machine learning method can provide clinicians with an automatic and accurate diagnostic tool for interpreting MCG data related to CAD, possibly promoting clinical acceptance.
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Affiliation(s)
- Xiaole Han
- Key Laboratory of Ultra-Weak Magnetic Field Measurement Technology, Ministry of Education, School of Instrumentation and Optoelectronic Engineering, Beihang University, People's Republic of China
- Zhejiang Provincial Key Laboratory of Ultra-Weak Magnetic-Field Space and Applied Technology, Hangzhou Innovation Institute, Beihang University, Hangzhou 310051, People's Republic of China
| | - Jiaojiao Pang
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
| | - Dong Xu
- National Institute of Extremely-Weak Magnetic Field Infrastructure, Hangzhou, People's Republic of China
| | - Ruizhe Wang
- Key Laboratory of Ultra-Weak Magnetic Field Measurement Technology, Ministry of Education, School of Instrumentation and Optoelectronic Engineering, Beihang University, People's Republic of China
- Zhejiang Provincial Key Laboratory of Ultra-Weak Magnetic-Field Space and Applied Technology, Hangzhou Innovation Institute, Beihang University, Hangzhou 310051, People's Republic of China
| | - Fei Xie
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
| | - Yanfei Yang
- Key Laboratory of Ultra-Weak Magnetic Field Measurement Technology, Ministry of Education, School of Instrumentation and Optoelectronic Engineering, Beihang University, People's Republic of China
- Zhejiang Provincial Key Laboratory of Ultra-Weak Magnetic-Field Space and Applied Technology, Hangzhou Innovation Institute, Beihang University, Hangzhou 310051, People's Republic of China
| | - Jiguang Sun
- Hangzhou Nuochi Life Science Co., Ltd, People's Republic of China
| | - Yu Li
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
| | - Ruochuan Li
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
| | - Xiaofei Yin
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
| | - Yansong Xu
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
| | - Jiaxin Fan
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
| | - Yiming Dong
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
| | - Xiaohui Wu
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
| | - Xiaoyun Yang
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
- Department of Gastroenterology, Qilu Hospital of Shandong University, Shandong Provincial Clinical Research Center for Digestive Disease, People's Republic of China
| | - Dexin Yu
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
- Department of Radiology, Qilu Hospital of Shandong University, People's Republic of China
| | - Dawei Wang
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
- Department of Radiology, Qilu Hospital of Shandong University, People's Republic of China
| | - Yang Gao
- Key Laboratory of Ultra-Weak Magnetic Field Measurement Technology, Ministry of Education, School of Instrumentation and Optoelectronic Engineering, Beihang University, People's Republic of China
- Zhejiang Provincial Key Laboratory of Ultra-Weak Magnetic-Field Space and Applied Technology, Hangzhou Innovation Institute, Beihang University, Hangzhou 310051, People's Republic of China
- National Institute of Extremely-Weak Magnetic Field Infrastructure, Hangzhou, People's Republic of China
- Institute of Large-Scale Scientific Facility and Centre for Zero Magnetic Field Science, Beihang University, People's Republic of China
| | - Min Xiang
- Key Laboratory of Ultra-Weak Magnetic Field Measurement Technology, Ministry of Education, School of Instrumentation and Optoelectronic Engineering, Beihang University, People's Republic of China
- Zhejiang Provincial Key Laboratory of Ultra-Weak Magnetic-Field Space and Applied Technology, Hangzhou Innovation Institute, Beihang University, Hangzhou 310051, People's Republic of China
- National Institute of Extremely-Weak Magnetic Field Infrastructure, Hangzhou, People's Republic of China
- Institute of Large-Scale Scientific Facility and Centre for Zero Magnetic Field Science, Beihang University, People's Republic of China
- Hefei National Laboratory, People's Republic of China
| | - Feng Xu
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
| | - Jinji Sun
- Key Laboratory of Ultra-Weak Magnetic Field Measurement Technology, Ministry of Education, School of Instrumentation and Optoelectronic Engineering, Beihang University, People's Republic of China
- Zhejiang Provincial Key Laboratory of Ultra-Weak Magnetic-Field Space and Applied Technology, Hangzhou Innovation Institute, Beihang University, Hangzhou 310051, People's Republic of China
- National Institute of Extremely-Weak Magnetic Field Infrastructure, Hangzhou, People's Republic of China
- Institute of Large-Scale Scientific Facility and Centre for Zero Magnetic Field Science, Beihang University, People's Republic of China
- Hefei National Laboratory, People's Republic of China
| | - Yuguo Chen
- Shandong Key Laboratory for Magnetic Field-free Medicine & Functional Imaging, Institute of Magnetic Field-free Medicine & Functional Imaging, Shandong University, People's Republic of China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, People's Republic of China
- National Innovation Platform for Industry-Education Intearation in Medicine-Engineering Interdisciplinary, Shandong University, People's Republic of China
| | - Xiaolin Ning
- Key Laboratory of Ultra-Weak Magnetic Field Measurement Technology, Ministry of Education, School of Instrumentation and Optoelectronic Engineering, Beihang University, People's Republic of China
- Zhejiang Provincial Key Laboratory of Ultra-Weak Magnetic-Field Space and Applied Technology, Hangzhou Innovation Institute, Beihang University, Hangzhou 310051, People's Republic of China
- National Institute of Extremely-Weak Magnetic Field Infrastructure, Hangzhou, People's Republic of China
- Institute of Large-Scale Scientific Facility and Centre for Zero Magnetic Field Science, Beihang University, People's Republic of China
- Hefei National Laboratory, People's Republic of China
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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: 14] [Impact Index Per Article: 4.7] [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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Eichler CE, Cheng LK, Paskaranandavadivel N, Du P, Bradshaw LA, Avci R. Effects of magnetogastrography sensor configurations in tracking slow wave propagation. Comput Biol Med 2020; 129:104169. [PMID: 33338892 DOI: 10.1016/j.compbiomed.2020.104169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 11/19/2020] [Accepted: 12/03/2020] [Indexed: 10/22/2022]
Abstract
Magnetogastrography (MGG) is a non-invasive method of assessing gastric slow waves (SWs) by recording the resultant magnetic fields. MGG can capture both SW frequency and propagation, and identify SW dysrhythmias that are associated with motility disorders. However, the impact of the restricted spatial coverage and sensor density on SW propagation tracking performance is unknown. This study simulated MGG using multiple anatomically specific torso geometries and two realistic SW propagation patterns to determine the effect of different sensor configurations on tracking SW propagation. The surface current density mapping and center-of-gravity tracking methods were used to compare four magnetometer array configurations: a reference system currently used in GI research and three hypothetical higher density and coverage arrays. SW propagation patterns identified with two hypothetical arrays (with coverage over at least the anterior of the torso) correlated significantly higher with simulated realistic 3 cycle-per-minute SW activity than the reference array (p = 0.016, p = 0.005). Furthermore, results indicated that most of the magnetic fields that contribute to the performance of SW propagation tracking were located on the anterior of the torso as further increasing the coverage did not significantly increase performance. A 30% decrease in sensor spacing within the same spatial coverage of the reference array also significantly increased correlation values by approximately 0.50 when the signal-to-noise ratio was 5 dB. This study provides evidence that higher density and coverage sensor layouts will improve the utility of MGG. Further work is required to investigate optimum sensor configurations across larger anatomical variations and other SW propagation patterns.
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Affiliation(s)
- Chad E Eichler
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Leo K Cheng
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand; Department of Surgery, Vanderbilt University, Nashville, TN, USA
| | | | - Peng Du
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | | | - Recep Avci
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
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Choice of Magnetometers and Gradiometers after Signal Space Separation. SENSORS 2017; 17:s17122926. [PMID: 29258189 PMCID: PMC5751446 DOI: 10.3390/s17122926] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 12/10/2017] [Accepted: 12/13/2017] [Indexed: 01/01/2023]
Abstract
BACKGROUND Modern Elekta Neuromag MEG devices include 102 sensor triplets containing one magnetometer and two planar gradiometers. The first processing step is often a signal space separation (SSS), which provides a powerful noise reduction. A question commonly raised by researchers and reviewers relates to which data should be employed in analyses: (1) magnetometers only, (2) gradiometers only, (3) magnetometers and gradiometers together. The MEG community is currently divided with regard to the proper answer. METHODS First, we provide theoretical evidence that both gradiometers and magnetometers result from the backprojection of the same SSS components. Then, we compare resting state and task-related sensor and source estimations from magnetometers and gradiometers in real MEG recordings before and after SSS. RESULTS SSS introduced a strong increase in the similarity between source time series derived from magnetometers and gradiometers (r² = 0.3-0.8 before SSS and r² > 0.80 after SSS). After SSS, resting state power spectrum and functional connectivity, as well as visual evoked responses, derived from both magnetometers and gradiometers were highly similar (Intraclass Correlation Coefficient > 0.8, r² > 0.8). CONCLUSIONS After SSS, magnetometer and gradiometer data are estimated from a single set of SSS components (usually ≤ 80). Equivalent results can be obtained with both sensor types in typical MEG experiments.
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Zhao C, Jiang S, Wu Y, Zhu J, Zhou D, Hailer B, Gronemeyer D, Van Leeuwen P. An Integrated Maximum Current Density Approach for Noninvasive Detection of Myocardial Infarction. IEEE J Biomed Health Inform 2017; 22:495-502. [PMID: 28092581 DOI: 10.1109/jbhi.2017.2649570] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We present a new approach of integrated maximum current density (IMCD) for the noninvasive detection of myocardial infarction (MI) using magnetocardiography (MCG) data acquired from a superconducting quantum interference device (SQUID) system. In this paper, we investigated the relationship of the maximum current density (MCD) in the current density map and the underlying equivalent current dipole (ECD) based on a novel method of reconstructing the ECD in the extremum circle of the magnetic field map. The performance of IMCD and the integrated ECD (IECD) approaches were also evaluated by using 61-channel MCG data from 39 healthy subjects and 102 patients with ST elevation myocardial infarction (STEMI). Statistical analysis of the healthy and STEMI groups demonstrate that the IMCD approach obtains sensitivity and specificity up to 91.2% and 84.6%, somewhat higher than that of IECD, respectively. The results indicate that IMCD provides spatiotemporal information regarding cardiac electrical activity during ventricular repolarization. This approach may be helpful to diagnose MI in clinic application. The physical concept of the approach is also explained in this paper.
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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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Kim JHK, Bradshaw LA, Pullan AJ, Cheng LK. Characterization of gastric electrical activity using magnetic field measurements: a simulation study. Ann Biomed Eng 2010; 38:177-86. [PMID: 19774463 PMCID: PMC2855966 DOI: 10.1007/s10439-009-9804-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2009] [Accepted: 09/15/2009] [Indexed: 01/08/2023]
Abstract
Gastric disorders are often associated with abnormal propagation of gastric electrical activity (GEA). The identification of clinically relevant parameters of GEA using noninvasive measures would therefore be highly beneficial for clinical diagnosis. While magnetogastrograms (MGG) are known to provide a noninvasive representation of GEA, standard methods for their analysis are limited. It has previously been shown in simplistic conditions that the surface current density (SCD) calculated from multichannel MGG measurements provides an estimate of the gastric source location and propagation velocity. We examine the accuracy of this technique using more realistic source models and an anatomically realistic volume conductor model. The results showed that the SCD method was able to resolve the GEA parameters more reliably when the dipole source was located within 100 mm of the sensor. Therefore, the theoretical accuracy of SCD method would be relatively diminished for patients with a larger body habitus, and particularly in those patients with significant truncal obesity. However, many patients with gastric motility disorders are relatively thin due to food intolerance, meaning that the majority of the population of gastric motility patients could benefit from the methods developed here. Large errors resulted when the source was located deep within the body due to the distorting effects of the secondary sources on the magnetic fields. Larger errors also resulted when the dipole was oriented normal to the sensor plane. This was believed to be due to the relatively small contribution of the dipole source when compared to the field produced by the volume conductor. The use of three orthogonal magnetic field components rather than just one component to calculate the SCD yielded marginally more accurate results when using a realistic dipole source. However, this slight increase in accuracy may not warrant the use of more complex vector channels in future superconducting quantum interference device designs. When multiple slow waves were present in the stomach, the SCD map contained only one maximum point corresponding to the more dominant source located in the distal stomach. Parameters corresponding to the slow wave in the proximal stomach were obtained once the dominant slow terminated at the antrum. Additional validation studies are warranted to address the utility of the SCD method to resolve parameters related to gastric slow waves in a clinical setting.
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Affiliation(s)
- J. H. K. Kim
- Auckland Bioengineering Institute, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - L. A. Bradshaw
- Department of Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - A. J. Pullan
- Auckland Bioengineering Institute, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
- Department of Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - L. K. Cheng
- Auckland Bioengineering Institute, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
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11
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Abstract
Gastric slow waves propagate in the electrical syncytium of the healthy stomach, being generated at a rate of approximately three times per minute in a pacemaker region along the greater curvature of the antrum and propagating distally towards the pylorus. Disease states are known to alter the normal gastric slow wave. Recent studies have suggested the use of biomagnetic techniques for assessing parameters of the gastric slow wave that have potential diagnostic significance. We present a study in which the gastric syncytium was uncoupled by mechanical division as we recorded serosal electric potentials along with multichannel biomagnetic signals and cutaneous potentials. By computing the surface current density (SCD) from multichannel biomagnetic recordings, we were able to quantify gastric slow wave propagation as well as the frequency and amplitude of the slow wave and to show that these correlate well with similar parameters from serosal electrodes. We found the dominant slow wave frequency to be an unreliable indicator of gastric uncoupling as uncoupling results in the appearance of multiple slow wave sources at various frequencies in external recordings. The percentage of power distributed in specific frequency ranges exhibited significant postdivision changes. Propagation velocity determined from SCD maps was a weak indicator of uncoupling in this work; we believe that the relatively low spatial resolution of our 19-channel biomagnetometer confounds the characterization of spatial variations in slow wave propagation velocities. Nonetheless, the biomagnetic technique represents a non-invasive method for accurate determination of clinically significant parameters of the gastric slow wave.
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Affiliation(s)
- L. A. Bradshaw
- Department of Surgery, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Physics & Astronomy, Vanderbilt University, Nashville, TN, USA,Department of Physics, Lipscomb University, Nashville, TN, USA
| | - A. Irimia
- Department of Radiology, University of California, San Diego, CA, USA
| | - J. A. Sims
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA
| | - W. O. Richards
- Department of Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
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12
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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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Jurkko R, Mäntynen V, Tapanainen JM, Montonen J, Väänänen H, Parikka H, Toivonen L. Non-invasive detection of conduction pathways to left atrium using magnetocardiography: validation by intra-cardiac electroanatomic mapping. Europace 2008; 11:169-77. [PMID: 19074785 DOI: 10.1093/europace/eun335] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Alteration in conduction from right to left atrium (LA) is linked to susceptibility to atrial fibrillation (AF). We examined whether different inter-atrial conduction pathways can be identified non-invasively by magnetocardiographic mapping (MCG). METHODS AND RESULTS In 27 patients undergoing catheter ablation of paroxysmal AF, LA activation sequence was determined during sinus rhythm using invasive electroanatomic mapping. Before this, 99-channel magnetocardiography was recorded over anterior chest. The orientation of the magnetic fields during the early (40-70 ms from P onset) and later part (last 50%) of LA depolarization was determined using pseudocurrent conversion. Breakthrough of electrical activation to LA occurred through Bachmann bundle (BB) in 14, margin of fossa ovalis (FO) in 3, coronary sinus ostial region (CS) in 2, and their combinations in 10 cases by invasive reference in total of 29 different P-waves. Based on the combination of pseudocurrent angles over early and late parts of LA activation, the MCG maps were divided to three types. These types correctly identified the LA breakthrough sites to BB, CS, FO, or their combinations in 27 of 29 (93%) cases. CONCLUSION Magnetocardiographic mapping seems capable of distinguishing inter-atrial conduction pathways. Recognizing the inter-atrial conduction pattern may assist in understanding the pathogenesis of AF and identifying the subgroups for patient-tailored therapy.
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Affiliation(s)
- Raija Jurkko
- Department of Cardiology Helsinki University Central Hospital, Helsinki, Finland.
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Ehman RL, Hendee WR, Welch MJ, Dunnick NR, Bresolin LB, Arenson RL, Baum S, Hricak H, Thrall JH. Blueprint for imaging in biomedical research. Radiology 2007; 244:12-27. [PMID: 17507725 DOI: 10.1148/radiol.2441070058] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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