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Escalona-Vargas D, Siegel ER, Bolin EH, Eswaran H. Fetal magnetocardiographic recordings with a prototype bed-based array system of optically-pumped magnetometers. Med Eng Phys 2024; 128:104175. [PMID: 38789219 PMCID: PMC11307323 DOI: 10.1016/j.medengphy.2024.104175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 04/23/2024] [Accepted: 05/06/2024] [Indexed: 05/26/2024]
Abstract
OBJECTIVE To record and extract features of fetal cardiac activities with a semi-rigid prototype optically-pumped magnetometers (OPM) sensor array. METHODS Fetal magnetocardiography (fMCG) data were collected from 15 pregnant women between 28 and 40 weeks gestation. Mothers were lying flat in a customized bed with sensors touching their abdomen from below using a prototype grid. fMCG was extracted to perform standard fetal heart rate variability (FHRV) analysis. RESULTS fMCG was observed in 13 of the 15 pregnant women. OPM FHRV indicators were in the range of previous SQUID studies. CONCLUSION Semi-rigid prototype OPM system has the ability to record quality fMCG. fMCG is capable of identifying lethal cardiac rhythm disturbances in the fetus. Our novel application of OPM technology may lower costs and increase maternal comfort, thus expanding fMCG's generalizability.
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Affiliation(s)
- Diana Escalona-Vargas
- Department of Pediatrics, Division of Neurology, University of Arkansas for Medical Sciences, Arkansas Children's Hospital, Little Rock, AR, USA; Department of Obstetrics and Gynecology, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
| | - Eric R Siegel
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Elijah H Bolin
- Department of Pediatrics, Division of Cardiology, University of Arkansas for Medical Sciences, Arkansas Children's Hospital, Little Rock, AR, USA
| | - Hari Eswaran
- Department of Obstetrics and Gynecology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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2
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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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3
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Killen SAS, Strasburger JF. Diagnosis and Management of Fetal Arrhythmias in the Current Era. J Cardiovasc Dev Dis 2024; 11:163. [PMID: 38921663 PMCID: PMC11204159 DOI: 10.3390/jcdd11060163] [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: 04/15/2024] [Revised: 05/18/2024] [Accepted: 05/20/2024] [Indexed: 06/27/2024] Open
Abstract
Diagnosis and management of fetal arrhythmias have changed over the past 40-50 years since propranolol was first used to treat fetal tachycardia in 1975 and when first attempts were made at in utero pacing for complete heart block in 1986. Ongoing clinical trials, including the FAST therapy trial for fetal tachycardia and the STOP-BLOQ trial for anti-Ro-mediated fetal heart block, are working to improve diagnosis and management of fetal arrhythmias for both mother and fetus. We are also learning more about how "silent arrhythmias", like long QT syndrome and other inherited channelopathies, may be identified by recognizing "subtle" abnormalities in fetal heart rate, and while echocardiography yet remains the primary tool for diagnosing fetal arrhythmias, research efforts continue to advance the clinical envelope for fetal electrocardiography and fetal magnetocardiography. Pharmacologic management of fetal arrhythmias remains one of the most successful achievements of fetal intervention. Patience, vigilance, and multidisciplinary collaboration are key to successful diagnosis and treatment.
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Affiliation(s)
- Stacy A. S. Killen
- Thomas P. Graham Jr. Division of Pediatric Cardiology, Department of Pediatrics, Vanderbilt University Medical Center, Monroe Carell Jr. Children’s Hospital at Vanderbilt, 2200 Children’s Way, Suite 5230, Nashville, TN 37232, USA
| | - Janette F. Strasburger
- Division of Cardiology, Departments of Pediatrics and Biomedical Engineering, Children’s Wisconsin, Herma Heart Institute, Medical College of Wisconsin, Milwaukee, WI 53226, USA;
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4
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Su S, Xu Z, He X, Zhang G, Wu H, Gao Y, Ma Y, Yin C, Ruan Y, Li K, Lin Q. Vector magnetocardiography using compact optically-pumped magnetometers. Heliyon 2024; 10:e29092. [PMID: 38601529 PMCID: PMC11004653 DOI: 10.1016/j.heliyon.2024.e29092] [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: 07/21/2023] [Revised: 03/29/2024] [Accepted: 03/31/2024] [Indexed: 04/12/2024] Open
Abstract
Optically pumped magnetometers can provide functionality for bio-magnetic field detection and mapping. This has attracted widespread attention from researchers in the biomedical science field. Magnetocardiography has been proven to be an effective method for examining heart disease. Notably, vector magnetocardiography obtains more spatial information than the conventional method by only taking a component that is perpendicular to the chest surface. In this work, a spin-exchange-relaxation-free (SERF) magnetometer with a compact size of 14 mm × 25 mm × 90 mm was developed. The device has a high sensitivity of 25 fT/ Hz . Meanwhile, in the multichannel working mode, synchronous sensor manipulation and data acquisition can be achieved through our control software without additional data acquisition boards. Since a typical SERF magnetometer only responds to dual-axis magnetic fields, two sensors are orthogonally arranged to form a vector detection channel. Our system consists of seven channels and allows 7 × 9 vector MCG mapping by scanning. High-quality heart vector signals are measured, and P peak, QRS peak, and T peak can be distinguished clearly. To better demonstrate the vectorial information, a vector scatter plot form is also provided. Through a basic bio-electric current model, it demonstrates that triaxial MCG measurements capture a richer spatial current information than traditional uniaxial MCG, offering substantial diagnostic potential for heart diseases and shedding more light on the inversion of cardiac issues.
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Affiliation(s)
- Shengran Su
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou, 310000, China
| | - Zhenyuan Xu
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou, 310000, China
| | - Xiang He
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou, 310000, China
| | - Guoyi Zhang
- Hangzhou Q-MAG Technology Co.,Ltd., Hangzhou, 310000, China
| | - Haijun Wu
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou, 310000, China
| | - Yalan Gao
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou, 310000, China
| | - Yueliang Ma
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou, 310000, China
| | - Chanling Yin
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou, 310000, China
| | - Yi Ruan
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou, 310000, China
| | - Kan Li
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou, 310000, China
| | - Qiang Lin
- Zhejiang Provincial Key Laboratory and Collaborative Innovation Center for Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou, 310000, China
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5
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Pȩczalski K, Sobiech J, Buchner T, Kornack T, Foley E, Janczak D, Jakubowska M, Newby D, Ford N, Zajdel M. Synchronous recording of magnetocardiographic and electrocardiographic signals. Sci Rep 2024; 14:4098. [PMID: 38374368 DOI: 10.1038/s41598-024-54126-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Accepted: 02/08/2024] [Indexed: 02/21/2024] Open
Abstract
We present a system for simultaneous recording of the electrocardiogram and the magnetocardiogram. The measurement system contained of printed carbon electrodes and SERF magnetometer. The use of this system confirms that the position of the end of the magnetic T wave extends further than the electric T wave, which is an important indicator for the diagnosis of cardiological patients and for drug arrhythmogenicity. We analyze this phenomenon in depth, and demonstrate, that it originates from the fundamental difference between electric and magnetic measurements. The measured value is always bipolar since the electric measurements require two electrodes. We demonstrate how the dual electric and magnetic measuring system adds a new information to the commonly used electrocardiographic diagnosis. The ECG should be interpreted as the spatial asymmetry of the electric cardiac potential, and not as the potential itself. The results seem to prove, that the relation between the magnetic and the electric imaging of neural activities may be broadly applied for the benefit of medical diagnosis in cardiology and many other fields, where the neural activity is measured. This is a pilot study which requires further confirmation at the clinical level.
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Affiliation(s)
| | - Judyta Sobiech
- Faculty of Physics, Warsaw University of Technology, Warsaw, Poland.
| | - Teodor Buchner
- Faculty of Physics, Warsaw University of Technology, Warsaw, Poland
| | | | | | - Daniel Janczak
- Faculty of Mechanical and Industrial Engineering, Warsaw University of Technology, Warsaw, Poland
| | - Małgorzata Jakubowska
- Faculty of Mechanical and Industrial Engineering, Warsaw University of Technology, Warsaw, Poland
| | | | - Nancy Ford
- Twinleaf LLC, Plainsboro, NJ, 08536, USA
| | - Maryla Zajdel
- Faculty of Physics, Warsaw University of Technology, Warsaw, Poland
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6
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Jaros R, Tomicova E, Martinek R. Template subtraction based methods for non-invasive fetal electrocardiography extraction. Sci Rep 2024; 14:630. [PMID: 38182757 PMCID: PMC10770155 DOI: 10.1038/s41598-024-51213-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 01/02/2024] [Indexed: 01/07/2024] Open
Abstract
Assessment of fetal heart rate (fHR) through non-invasive fetal electrocardiogram (fECG) is challenging task. This study compares the performance of five template subtraction (TS) methods on Labor (12 5-min recordings) and Pregnancy datasets (10 20-min recordings). The methods include TS without adaptation, TS using singular value decomposition (TS[Formula: see text]), TS using linear prediction (TS[Formula: see text]), TS using scaling factor (TS[Formula: see text]), and sequential analysis (SA). The influence of the chosen maternal wavelet for the continuous wavelet transform (CWT) detector is also compared. The F1 score was used to measure performance. Each recording in both datasets consisted of four signals, resulting in a total comparison of 88 signals for the TS-based methods. The study reported the following results: F1 = 95.71% with TS, F1 = 95.93% with TS[Formula: see text], F1 = 95.30% with TS[Formula: see text], F1 = 95.82% with TS[Formula: see text], and F1 = 95.99% with SA. The study identified gaus3 as the suitable maternal wavelet for fetal R-peak detection using the CWT detector. Furthermore, the study classified signals from the tested datasets into categories of high, medium, and low quality, providing valuable insights for subsequent fECG signal extraction. This research contributes to advancing the understanding of non-invasive fECG signal processing and lays the groundwork for improving fetal monitoring in clinical settings.
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Affiliation(s)
- Rene Jaros
- Department of Cybernetics and Biomedical Engineering, Faculty of Electrical Engineering and Computer Science, VSB-Technical University of Ostrava, 17. listopadu 2172/15, 708 00, Ostrava, Czechia.
| | - Eva Tomicova
- Department of Cybernetics and Biomedical Engineering, Faculty of Electrical Engineering and Computer Science, VSB-Technical University of Ostrava, 17. listopadu 2172/15, 708 00, Ostrava, Czechia
| | - Radek Martinek
- Department of Cybernetics and Biomedical Engineering, Faculty of Electrical Engineering and Computer Science, VSB-Technical University of Ostrava, 17. listopadu 2172/15, 708 00, Ostrava, Czechia
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7
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Yoshida K, Inaba T, Horigome H, Nogami A, Aonuma K, Ieda M. Magnetocardiographic risk stratification in patients with Brugada-pattern ST-elevation. J Interv Card Electrophysiol 2024; 67:35-37. [PMID: 37691081 DOI: 10.1007/s10840-023-01641-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 09/04/2023] [Indexed: 09/12/2023]
Affiliation(s)
- Kentaro Yoshida
- Department of Cardiology, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Japan.
- Department of Cardiology, Ibaraki Prefectural Central Hospital, Kasama, Japan.
| | - Takeshi Inaba
- Department of Cardiology, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Japan
| | - Hitoshi Horigome
- Department of Child Health, Institute of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Akihiko Nogami
- Department of Cardiology, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Japan
| | - Kazutaka Aonuma
- Department of Cardiology, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Japan
| | - Masaki Ieda
- Department of Cardiology, Institute of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Japan
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8
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Xu K, Ren X, Xiang Y, Zhang M, Zhao X, Ma K, Tian Y, Wu D, Zeng Z, Wang G. Multi-Parameter Optimization of Rubidium Laser Optically Pumped Magnetometers with Geomagnetic Field Intensity. SENSORS (BASEL, SWITZERLAND) 2023; 23:8919. [PMID: 37960618 PMCID: PMC10648743 DOI: 10.3390/s23218919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 10/25/2023] [Accepted: 10/26/2023] [Indexed: 11/15/2023]
Abstract
Rubidium laser optically pumped magnetometers (OPMs) are widely used magnetic sensors based on the Zeeman effect, laser pumping, and magnetic resonance principles. They measure the magnetic field by measuring the magnetic resonance signal passing through a rubidium atomic gas cell. The quality of the magnetic resonance signal is a necessary condition for a magnetometer to achieve high sensitivity. In this research, to obtain the best magnetic resonance signal of rubidium laser OPMs in the Earth's magnetic field intensity, the experiment system of rubidium laser OPMs is built with a rubidium atomic gas cell as the core component. The linewidth and amplitude ratio (LAR) of magnetic resonance signals is utilized as the optimization objective function. The magnetic resonance signals of the magnetometer experiment system are experimentally measured for different laser frequencies, radio frequency (RF) intensities, laser powers, and atomic gas cell temperatures in a background magnetic field of 50,765 nT. The experimental results indicate that optimizing these parameters can reduce the LAR by one order of magnitude. This shows that the optimal parameter combination can effectively improve the sensitivity of the magnetometer. The sensitivity defined using the noise spectral density measured under optimal experimental parameters is 1.5 pT/Hz1/2@1 Hz. This work will provide key technical support for rubidium laser OPMs' product development.
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Affiliation(s)
| | - Xiuyan Ren
- Department of Nuclear Technology and Application, China Institute of Atomic Energy, Beijing 102413, China
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9
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Wang Y, Zhao ZG, Chai Z, Fang JC, Chen M. Electromagnetic field and cardiovascular diseases: A state-of-the-art review of diagnostic, therapeutic, and predictive values. FASEB J 2023; 37:e23142. [PMID: 37650634 DOI: 10.1096/fj.202300201rr] [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: 02/04/2023] [Revised: 07/20/2023] [Accepted: 08/02/2023] [Indexed: 09/01/2023]
Abstract
Despite encouraging advances in early diagnosis and treatment, cardiovascular diseases (CVDs) remained a leading cause of morbidity and mortality worldwide. Increasing evidence has shown that the electromagnetic field (EMF) influences many biological processes, which has attracted much attention for its potential therapeutic and diagnostic modalities in multiple diseases, such as musculoskeletal disorders and neurodegenerative diseases. Nonionizing EMF has been studied as a therapeutic or diagnostic tool in CVDs. In this review, we summarize the current literature ranging from in vitro to clinical studies focusing on the therapeutic potential (external EMF) and diagnostic potential (internal EMF generated from the heart) of EMF in CVDs. First, we provided an overview of the therapeutic potential of EMF and associated mechanisms in the context of CVDs, including cardiac arrhythmia, myocardial ischemia, atherosclerosis, and hypertension. Furthermore, we investigated the diagnostic and predictive value of magnetocardiography in CVDs. Finally, we discussed the critical steps necessary to translate this promising approach into clinical practice.
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Affiliation(s)
- Yan Wang
- Laboratory of Heart Valve Disease, West China Hospital, Sichuan University, Chengdu, Sichuan, China
- Department of Cardiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Zhen-Gang Zhao
- Laboratory of Heart Valve Disease, West China Hospital, Sichuan University, Chengdu, Sichuan, China
- Department of Cardiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Zheng Chai
- Laboratory of Heart Valve Disease, West China Hospital, Sichuan University, Chengdu, Sichuan, China
- Department of Cardiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Jian-Cheng Fang
- School of Instrumentation Science and Opto-Electronics Engineering, Beihang University, Beijing, China
| | - Mao Chen
- Laboratory of Heart Valve Disease, West China Hospital, Sichuan University, Chengdu, Sichuan, China
- Department of Cardiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
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10
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Joglar JA, Kapa S, Saarel EV, Dubin AM, Gorenek B, Hameed AB, Lara de Melo S, Leal MA, Mondésert B, Pacheco LD, Robinson MR, Sarkozy A, Silversides CK, Spears D, Srinivas SK, Strasburger JF, Tedrow UB, Wright JM, Zelop CM, Zentner D. 2023 HRS expert consensus statement on the management of arrhythmias during pregnancy. Heart Rhythm 2023; 20:e175-e264. [PMID: 37211147 DOI: 10.1016/j.hrthm.2023.05.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 05/12/2023] [Indexed: 05/23/2023]
Abstract
This international multidisciplinary expert consensus statement is intended to provide comprehensive guidance that can be referenced at the point of care to cardiac electrophysiologists, cardiologists, and other health care professionals, on the management of cardiac arrhythmias in pregnant patients and in fetuses. This document covers general concepts related to arrhythmias, including both brady- and tachyarrhythmias, in both the patient and the fetus during pregnancy. Recommendations are provided for optimal approaches to diagnosis and evaluation of arrhythmias; selection of invasive and noninvasive options for treatment of arrhythmias; and disease- and patient-specific considerations when risk stratifying, diagnosing, and treating arrhythmias in pregnant patients and fetuses. Gaps in knowledge and new directions for future research are also identified.
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Affiliation(s)
- José A Joglar
- The University of Texas Southwestern Medical Center, Dallas, Texas
| | | | - Elizabeth V Saarel
- St. Luke's Health System, Boise, Idaho, and Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, Ohio
| | | | | | | | | | | | | | - Luis D Pacheco
- The University of Texas Medical Branch at Galveston, Galveston, Texas
| | | | - Andrea Sarkozy
- University Hospital of Antwerp, University of Antwerp, Antwerp, Belgium
| | | | - Danna Spears
- University Health Network, Toronto, Ontario, Canada
| | - Sindhu K Srinivas
- University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | | | | | | | - Carolyn M Zelop
- The Valley Health System, Ridgewood, New Jersey; New York University Grossman School of Medicine, New York, New York
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11
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Brisinda D, Fenici P, Fenici R. Clinical magnetocardiography: the unshielded bet-past, present, and future. Front Cardiovasc Med 2023; 10:1232882. [PMID: 37636301 PMCID: PMC10448194 DOI: 10.3389/fcvm.2023.1232882] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 06/23/2023] [Indexed: 08/29/2023] Open
Abstract
Magnetocardiography (MCG), which is nowadays 60 years old, has not yet been fully accepted as a clinical tool. Nevertheless, a large body of research and several clinical trials have demonstrated its reliability in providing additional diagnostic electrophysiological information if compared with conventional non-invasive electrocardiographic methods. Since the beginning, one major objective difficulty has been the need to clean the weak cardiac magnetic signals from the much higher environmental noise, especially that of urban and hospital environments. The obvious solution to record the magnetocardiogram in highly performant magnetically shielded rooms has provided the ideal setup for decades of research demonstrating the diagnostic potential of this technology. However, only a few clinical institutions have had the resources to install and run routinely such highly expensive and technically demanding systems. Therefore, increasing attempts have been made to develop cheaper alternatives to improve the magnetic signal-to-noise ratio allowing MCG in unshielded hospital environments. In this article, the most relevant milestones in the MCG's journey are reviewed, addressing the possible reasons beyond the currently long-lasting difficulty to reach a clinical breakthrough and leveraging the authors' personal experience since the early 1980s attempting to finally bring MCG to the patient's bedside for many years thus far. Their nearly four decades of foundational experimental and clinical research between shielded and unshielded solutions are summarized and referenced, following the original vision that MCG had to be intended as an unrivaled method for contactless assessment of the cardiac electrophysiology and as an advanced method for non-invasive electroanatomical imaging, through multimodal integration with other non-fluoroscopic imaging techniques. Whereas all the above accounts for the past, with the available innovative sensors and more affordable active shielding technologies, the present demonstrates that several novel systems have been developed and tested in multicenter clinical trials adopting both shielded and unshielded MCG built-in hospital environments. The future of MCG will mostly be dependent on the results from the ongoing progress in novel sensor technology, which is relatively soon foreseen to provide multiple alternatives for the construction of more compact, affordable, portable, and even wearable devices for unshielded MCG inside hospital environments and perhaps also for ambulatory patients.
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Affiliation(s)
- D. Brisinda
- Dipartimento Scienze dell'invecchiamento, ortopediche e reumatologiche, Fondazione Policlinico Universitario Agostino Gemelli, IRCCS, Rome, Italy
- School of Medicine and Surgery, Catholic University of the Sacred Heart, Rome, Italy
- Biomagnetism and Clinical Physiology International Center (BACPIC), Rome, Italy
| | - P. Fenici
- School of Medicine and Surgery, Catholic University of the Sacred Heart, Rome, Italy
- Biomagnetism and Clinical Physiology International Center (BACPIC), Rome, Italy
| | - R. Fenici
- Biomagnetism and Clinical Physiology International Center (BACPIC), Rome, Italy
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12
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Wurm D, Ewert P, Fierlinger P, Wakai RT, Wallner V, Wunderl L, Wacker-Gußmann A. A Small Scale Optically Pumped Fetal Magnetocardiography System. J Clin Med 2023; 12:jcm12103380. [PMID: 37240486 DOI: 10.3390/jcm12103380] [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: 02/21/2023] [Revised: 04/26/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023] Open
Abstract
INTRODUCTION Fetal magnetocardiography (fMCG) is considered the best technique for diagnosis of fetal arrhythmia. It is superior to more widely used methods such as fetal, fetal electrocardiography, and cardiotocography for evaluation of fetal rhythm. The combination of fMCG and fetal echocardiography can provide a more comprehensive evaluation of fetal cardiac rhythm and function than is currently possible. In this study, we demonstrate a practical fMCG system based on optically pumped magnetometers (OPMs). METHODS Seven pregnant women with uncomplicated pregnancies underwent fMCG at 26-36 weeks' gestation. The recordings were made using an OPM-based fMCG system and a person-sized magnetic shield. The shield is much smaller than a shielded room and provides easy access with a large opening that allows the pregnant woman to lie comfortably in a prone position. RESULTS The data show no significant loss of quality compared to data acquired in a shielded room. Measurements of standard cardiac time intervals yielded the following results: PR = 104 ± 6 ms, QRS = 52.6 ± 1.5 ms, and QTc = 387 ± 19 ms. These results are compatible with those from prior studies performed using superconducting quantum interference device (SQUID) fMCG systems. CONCLUSIONS To our knowledge, this is the first European fMCG device with OPM technology commissioned for basic research in a pediatric cardiology unit. We demonstrated a patient-friendly, comfortable, and open fMCG system. The data yielded consistent cardiac intervals, measured from time-averaged waveforms, compatible with published SQUID and OPM data. This is an important step toward making the method widely accessible.
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Affiliation(s)
- David Wurm
- Chair E66, School of Natural Sciences, Technical University of Munich, 80636 Munich, Germany
| | - Peter Ewert
- Department of Congenital Heart Disease and Pediatric Cardiology, German Heart Center, 80636 Munich, Germany
| | - Peter Fierlinger
- Chair E66, School of Natural Sciences, Technical University of Munich, 80636 Munich, Germany
| | - Ronald T Wakai
- Department of Medical Physics, University of Wisconsin Madison, Madison, WI 53706, USA
| | - Verena Wallner
- Chair E66, School of Natural Sciences, Technical University of Munich, 80636 Munich, Germany
| | - Lena Wunderl
- Chair E66, School of Natural Sciences, Technical University of Munich, 80636 Munich, Germany
| | - Annette Wacker-Gußmann
- Department of Congenital Heart Disease and Pediatric Cardiology, German Heart Center, 80636 Munich, Germany
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13
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Tardelli GP, Phan T, Strasburger J, Baffa O, Wakai R. Ferrite Shield to Enhance the Performance of Optically Pumped Magnetometers for Fetal Magnetocardiography. J Clin Med 2023; 12:jcm12093078. [PMID: 37176519 PMCID: PMC10179327 DOI: 10.3390/jcm12093078] [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: 03/01/2023] [Revised: 04/08/2023] [Accepted: 04/21/2023] [Indexed: 05/15/2023] Open
Abstract
Fetal magnetocardiography (fMCG) has proven to be an important tool for the prenatal monitoring of electrical cardiac activity; however, the high cost of superconducting quantum instrumentation (SQUID) poses a limitation for the dissemination of fMCG as a routine clinical technique. Recently, optically pumped magnetometers (OPMs) operating within person-sized, cylindrical shields have made fMCG more practical, but environmental magnetic interference entering through the shield opening substantially degrades the quality of fMCG signals. The goal of this study was to further attenuate these interferences by placing the OPM array within a small ferrite shield. FMCG recordings were made with and without the ferrite shield in ten subjects inside a person-sized, three-layer mu-metal cylindrical shield. Although the fetal signal was slightly attenuated, the environmental interference was reduced substantially, and maternal interference was also diminished. This increased the signal-to-noise ratio significantly and improved the resolution of the smaller waveform components. The performance improvement was highest in the axial direction and compensated for a major weakness of open-ended, person-sized shields. The ferrite shield is especially beneficial for the deployment of triaxial OPM sensors, which require effective shielding in all directions.
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Affiliation(s)
- Gabriela P Tardelli
- Department of Medical Physics, Wisconsin Institute for Medical Research, University of Wisconsin-Madison, Madison, WI 53705, USA
- Department of Physics, School of Philosophy, Science and Letters at Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-900, SP, Brazil
| | - Tan Phan
- Department of Medical Physics, Wisconsin Institute for Medical Research, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Janette Strasburger
- Division of Cardiology, Department of Pediatrics, Children's Hospital of Wisconsin-Milwaukee, Milwaukee, WI 53226, USA
| | - Oswaldo Baffa
- Department of Physics, School of Philosophy, Science and Letters at Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-900, SP, Brazil
| | - Ronald Wakai
- Department of Medical Physics, Wisconsin Institute for Medical Research, University of Wisconsin-Madison, Madison, WI 53705, USA
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14
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Phan T, Strasburger JF, Tardelli GP, Eckstein G, Wakai RT. Magnetomechanical fetal cardiac imaging: Feasibility of a new multimodal technique. Heart Rhythm 2023; 20:633-634. [PMID: 36566889 PMCID: PMC10065896 DOI: 10.1016/j.hrthm.2022.12.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 12/13/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022]
Affiliation(s)
- Tan Phan
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin
| | - Janette F Strasburger
- Department of Pediatrics, Division of Cardiology, Children's Hospital of Wisconsin, Milwaukee, Wisconsin
| | - Gabriela Pazin Tardelli
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin; Departamento de Física-FFCLRP, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Gretchen Eckstein
- Department of Pediatrics, Division of Cardiology, Children's Hospital of Wisconsin, Milwaukee, Wisconsin
| | - Ronald T Wakai
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin.
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15
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Xiao W, Sun C, Shen L, Feng Y, Liu M, Wu Y, Liu X, Wu T, Peng X, Guo H. A movable unshielded magnetocardiography system. SCIENCE ADVANCES 2023; 9:eadg1746. [PMID: 36989361 PMCID: PMC10058232 DOI: 10.1126/sciadv.adg1746] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 02/28/2023] [Indexed: 06/19/2023]
Abstract
Magnetocardiography (MCG), which uses high-sensitivity magnetometers to record magnetic field signals generated by electrical activity in the heart, is a noninvasive method for evaluating heart diseases such as arrhythmia and ischemia. The MCG measurements usually require the participant keeping still in a magnetically shielded room due to the immovable sensor and noisy external environments. These requirements limit MCG applications, such as exercise MCG tests and long-term MCG observations, which are useful for early detections of heart diseases. Here, we introduce a movable MCG system that can clearly record MCG signals of freely behaving participants in an unshielded environment. On the basis of optically pumped magnetometers with a sensitivity of 140 fT/Hz1/2, we successfully demonstrated the resting MCG and the exercise MCG tests. Our method is promising to realize a practical movable multichannel unshielded MCG system that nearly sets no limits to participants and brings another kind of insight into the medical diagnosis of heart disease.
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Affiliation(s)
| | | | - Liang Shen
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics, and Center for Quantum Information Technology, Peking University, Beijing 100871, China
| | - Yulong Feng
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics, and Center for Quantum Information Technology, Peking University, Beijing 100871, China
| | - Meng Liu
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics, and Center for Quantum Information Technology, Peking University, Beijing 100871, China
| | - Yulong Wu
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics, and Center for Quantum Information Technology, Peking University, Beijing 100871, China
| | - Xiyu Liu
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics, and Center for Quantum Information Technology, Peking University, Beijing 100871, China
| | - Teng Wu
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics, and Center for Quantum Information Technology, Peking University, Beijing 100871, China
| | - Xiang Peng
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics, and Center for Quantum Information Technology, Peking University, Beijing 100871, China
| | - Hong Guo
- State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics, and Center for Quantum Information Technology, Peking University, Beijing 100871, China
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16
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Systematic review of long QT syndrome identified during fetal life. Heart Rhythm 2022; 20:596-606. [PMID: 36566891 DOI: 10.1016/j.hrthm.2022.12.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 12/15/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022]
Abstract
Fetal long QT syndrome (LQTS) may present with sinus bradycardia, functional 2:1 atrioventricular block (AVB), and ventricular arrhythmias (ventricular tachycardia [VT]/torsades de pointes [TdP]) and lead to fetal or postnatal death. We performed a systematic review and individual participant data meta-analysis of 83 studies reporting outcomes of 265 fetuses for which suspected LQTS was confirmed postnatally and determined risk of adverse perinatal and postnatal outcomes using logistic and stepwise logistic regression. A longer fetal QTc was more predictive of death than any other antenatal factor (receiver operating characteristic [ROC] area under the curve [AUC] 0.85; 95% confidence interval [CI] 0.66-1.00). Risk of death was significantly increased with fetal QTc >600 ms. Neither fetal heart rate nor heart rate z-score predicted death (ROC AUC 0.51; 95% CI 0.31-0.71; and ROC AUC 0.59; 95% CI 0.37-0.80, respectively). The combination of antenatal VT/TdP or functional 2:1 AVB and lack of family history of LQTS was also highly predictive of death (ROC AUC 0.82; 95% CI 0.76-0.88). Our data provide clinical screening tools to enable prediction and intervention for fetuses with LQTS at risk of death.
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17
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Strasburger JF, Eckstein G, Butler M, Noffke P, Wacker-Gussmann A. Fetal Arrhythmia Diagnosis and Pharmacologic Management. J Clin Pharmacol 2022; 62 Suppl 1:S53-S66. [PMID: 36106782 PMCID: PMC9543141 DOI: 10.1002/jcph.2129] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 07/25/2022] [Indexed: 11/24/2022]
Abstract
One of the most successful achievements of fetal intervention is the pharmacologic management of fetal arrhythmias. This management usually takes place during the second or third trimester. While most arrhythmias in the fetus are benign, both tachy‐ and bradyarrhythmias can lead to fetal hydrops or cardiac dysfunction and require treatment under certain conditions. This review will highlight precise diagnosis by fetal echocardiography and magnetocardiography, the 2 primary means of diagnosing fetuses with arrhythmia. Additionally, transient or hidden arrhythmias such as bundle branch block, QT prolongation, and torsades de pointes, which can lead to cardiomyopathy and sudden unexplained death in the fetus, may also need pharmacologic treatment. The review will address the types of drug therapies; current knowledge of drug usage, efficacy, and precautions; and the transition to neonatal treatments when indicated. Finally, we will highlight new assessments, including the role of the nurse in the care of fetal arrhythmias. The prognosis for the human fetus with arrhythmias continues to improve as we expand our ability to provide intensive care unit–like monitoring, to better understand drug treatments, to optimize subsequent pregnancy monitoring, to effectively predict timing for delivery, and to follow up these conditions into the neonatal period and into childhood. Coordinated initiatives that facilitate clinical fetal research are needed to address gaps in knowledge and to facilitate fetal drug and device development.
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Affiliation(s)
- Janette F Strasburger
- Division of Cardiology, Departments of Pediatrics and Biomedical Engineering, Children's Wisconsin, Herma Heart Institute, and Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Gretchen Eckstein
- Division of Cardiology, Departments of Pediatrics and Biomedical Engineering, Children's Wisconsin, Herma Heart Institute, and Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Mary Butler
- College of Nursing, University of Wisconsin-Oshkosh, Oshkosh, Wisconsin, USA
| | - Patrick Noffke
- Division of Cardiology, Departments of Pediatrics and Biomedical Engineering, Children's Wisconsin, Herma Heart Institute, and Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Annette Wacker-Gussmann
- German Heart Center, Department of Congenital Heart Disease and Pediatric Cardiology Munich, Munchen, Bavaria, Germany
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18
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Wacker-Gussmann A, Strasburger JF, Wakai RT. Contribution of Fetal Magnetocardiography to Diagnosis, Risk Assessment, and Treatment of Fetal Arrhythmia. J Am Heart Assoc 2022; 11:e025224. [PMID: 35904205 PMCID: PMC9375504 DOI: 10.1161/jaha.121.025224] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background Fetal echocardiography has been the mainstay of fetal arrhythmia diagnosis; however, fetal magnetocardiography (fMCG) has recently become clinically available. We sought to determine to what extent fMCG contributed to the precision and accuracy of fetal arrhythmia diagnosis and risk assessment, and in turn, how this altered pregnancy management. Methods and Results We reviewed fMCG tracings and medical records of 215 pregnancies referred to the Biomagnetism Laboratory, UW‐Madison, over the last 10 years, because of fetal arrhythmia or risk of arrhythmia. We compared referral diagnosis and treatment with fMCG diagnosis using a rating scale and restricted our review to the 144 subjects from the tachycardia, bradycardia/AV block, and familial long QT syndrome categories. Additional fMCG findings beyond those of the referring echocardiogram, or an alternative diagnosis were seen in 117/144 (81%), and 81 (56%) were critical changes. Eight (5.5%) had resolution of arrhythmia before fMCG. At least moderate changes in management were seen in 109/144 (76%) fetuses, of which 35/144 (24%) were major. The most diverse fMCG presentation was long QT syndrome, present in all 3 referral categories. Four of 5 stillbirths were seen with long QT syndrome. Nine fetuses showed torsades de pointes ventricular tachycardia, of which only 2 were recognized before fMCG. Conclusions FMCG has a significant impact on prenatal diagnosis and management of arrhythmias or familial arrhythmia risk, which cannot be fully met by existing technology. The combination of fMCG and fetal echocardiography in fetal care centers will be needed in the future to optimize care.
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Affiliation(s)
- Annette Wacker-Gussmann
- Department of Congential Heart Disease and Pediatric Cardiology German Heart Center Munich Germany
| | - Janette F Strasburger
- Departments of Pediatrics and Biomedical Engineering Children's Wisconsin and Herma Heart Institute Milwaukee WI
| | - Ronald T Wakai
- Department of Medical Physics University of Wisconsin-Madison Madison WI
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19
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Karthik G, Samson Ravindran R. Heuristic RNN-based Kalman filter for fetal electrocardiogram extraction. JOURNAL OF INTELLIGENT & FUZZY SYSTEMS 2022. [DOI: 10.3233/jifs-221549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Fetal Electrocardiogram (FECG) analysis helps in diagnosis of fetal heart. Extracting FECG from composite abdominal signal that contains noises like maternal ECG (MECG), electrical interference etc is a topic of great research interest, and several approaches have been reported. The proposed method is Heuristic RNN-based Kalman Filter for Fetal Electrocardiogram Extraction (HRKFFEE) which is based on redundant noise and signal patterns in the residual signal of FECG and MECG. Two functional blocks are used in the proposed method. The first functional block is based on Heuristic RNN equipped with legacy Long Short-Term Memory (LSTM) for assembling a knowledgebase and the second functional block is RNN-based Kalman filter. Upon testing, the proposed method delivers better average values of accuracy, F Score, Precision and Specificity as 93.118%, 93.106%, 92.9495 % and 92.98% respectively.
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Affiliation(s)
- G.L. Karthik
- Department of Biomedical Engineering, SNS College of Technology (Autonomous), Coimbatore
| | - R. Samson Ravindran
- Department of Electronics and Communication Engineering, Mahendra Engineering College (Autonomous), Namakkal
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20
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B A, J SK, George S, Arora M. Heart rate estimation and validation algorithm for fetal phonocardiography. Physiol Meas 2022; 43. [PMID: 35724646 DOI: 10.1088/1361-6579/ac7a8c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 06/20/2022] [Indexed: 11/11/2022]
Abstract
Fetal heart rate (FHR) is an important parameter for assessing fetal well-being and is usually measured by doppler ultrasound. Fetal phonocardiography can provide non-invasive, easy-to-use and passive alternative for fetal monitoring method if reliable FHR measurements can be made even in noisy clinical environments. In this work we present an automatic algorithm to determine fetal heart rate from the fetal heart sound recordings in a noisy clinical environment. Using an electronic stethoscope fetal heart sounds were recorded from the expecting mother's abdomen, during weeks 30-40 of their pregnancy. Of these, 60 recordings were analyzed manually by two observers to obtain reference heart rate measurement. An algorithm was developed to determine FHR using envelope detection and autocorrelation of the signals. Algorithm performance was improved by implementing peak validation algorithm utilizing knowledge of valid FHR from prior windows and power spectral density function. The improvements in accuracy and reliability of algorithm were measured by mean absolute error and positive precent agreement. By including the validation step, the mean absolute error reduced from 11.50 to 7.54 beats per minute and positive percent agreement improved from 81% to 87%. The proposed algorithms provide good accuracy overall but are sensitive to the noises in recording environment that influence the quality of the signals.
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Affiliation(s)
- Amrutha B
- Centre for Product Design and Manufacturing, Indian Institute of Science, CPDM office, CV raman, road,Devasandra Layout,, road,Devasandra Layout,, road,Devasandra Layout,, road,Devasandra Layout,, Bengalurur, Bangalore, 560012, INDIA
| | - Sidhesh Kumar J
- Indian Institute of Science, CPDM office, CV raman, road,Devasandra Layout,, road,Devasandra Layout,, road,Devasandra Layout,, road,Devasandra Layout,, Bengalurur, Bangalore, Karnataka, 560012, INDIA
| | - Shirley George
- St.Johns medical college Hospital, St. John's National Academy of Health Sciences, Sarjapur Road, Bangalore, 560034, INDIA
| | - Manish Arora
- Centre for Product Design and Manufacturing, Indian Institute of Science, CPDM office, CV raman, road,Devasandra Layout,, road,Devasandra Layout,, road,Devasandra Layout,, road,Devasandra Layout,, Bengalurur, Bangalore, 560012, INDIA
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21
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Zhao W, Tao X, Ye C, Tao Y. Tunnel Magnetoresistance Sensor with AC Modulation and Impedance Compensation for Ultra-Weak Magnetic Field Measurement. SENSORS 2022; 22:s22031021. [PMID: 35161769 PMCID: PMC8838231 DOI: 10.3390/s22031021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 11/20/2022]
Abstract
Tunnel magnetoresistance (TMR) is a kind of magnetic sensor with the advantages of low cost and high sensitivity. For ultra-weak and low-frequency magnetic field measurement, the TMR sensor is affected by the 1/f noise. This paper proposes an AC modulation method with impedance compensation to improve the performance. The DC and AC characteristics of the sensors were measured and are presented here. It was found that both the equivalent resistance and capacitor of the sensors are affected by the external magnetic field. The TMR sensors are connected as a push–pull bridge circuit to measure the magnetic field. To reduce the common-mode noise, two similar bridge circuits form a magnetic gradiometer. Experimental results show that the sensor’s sensitivity in the low-frequency range is obviously improved by the modulation and impedance compensation. The signal-to-noise ratio of the sensor at 1 Hz was increased about 25.3 dB by the AC modulation, impedance compensation, and gradiometer measurement setup. In addition, the sensitivity of the sensor was improved from 165.2 to 222.1 mV/V/mT. Ultra-weak magnetic signals, namely magnetocardiography signals of two human bodies, were measured by the sensor in an unshielded environment. It was seen that the R peak of MCG can be clearly visualized from the recorded signal.
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Affiliation(s)
- Wenlei Zhao
- School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China; (W.Z.); (X.T.); (C.Y.)
| | - Xinchen Tao
- School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China; (W.Z.); (X.T.); (C.Y.)
| | - Chaofeng Ye
- School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China; (W.Z.); (X.T.); (C.Y.)
- China Shanghai Engineering Research Center of Energy Efficient and Custom AI IC, Shanghai 201210, China
| | - Yu Tao
- School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China; (W.Z.); (X.T.); (C.Y.)
- Correspondence:
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22
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Sometti D, Semeia L, Baek S, Chen H, Righetti G, Dax J, Kronlage C, Kirchgässner M, Romano A, Heilos J, Staber D, Oppold J, Middelmann T, Braun C, Broser P, Marquetand J. Muscle Fatigue Revisited – Insights From Optically Pumped Magnetometers. Front Physiol 2021; 12:724755. [PMID: 34975515 PMCID: PMC8718712 DOI: 10.3389/fphys.2021.724755] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 11/25/2021] [Indexed: 11/13/2022] Open
Abstract
So far, surface electromyography (sEMG) has been the method of choice to detect and evaluate muscle fatigue. However, recent advancements in non-cryogenic quantum sensors, such as optically pumped magnetometers (OPMs), enable interesting possibilities to flexibly record biomagnetic signals. Yet, a magnetomyographic investigation of muscular fatigue is still missing. Here, we simultaneously used sEMG (4 surface electrode) and OPM-based magnetomyography (OPM-MMG, 4 sensors) to detect muscle fatigue during a 3 × 1-min isometric contractions of the left rectus femoris muscle in 7 healthy participants. Both signals exhibited the characteristic spectral compression distinctive for muscle fatigue. OPM-MMG and sEMG slope values, used to quantify the spectral compression of the signals, were positively correlated, displaying similarity between the techniques. Additionally, the analysis of the different components of the magnetic field vector enabled speculations regarding the propagation of the muscle action potentials (MAPs). Altogether these results show the feasibility of the magnetomyographic approach with OPMs and propose a potential alternative to sEMG for the study of muscle fatigue.
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Affiliation(s)
- Davide Sometti
- Department of Neural Dynamics and Magnetoencephalography, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- MEG-Center, University of Tübingen, Tübingen, Germany
- Graduate Training Centre of Neuroscience, International Max Planck Research School, University of Tübingen, Tübingen, Germany
- Center for Pediatric Clinical Studies, University of Tübingen, Tübingen, Germany
| | - Lorenzo Semeia
- Graduate Training Centre of Neuroscience, International Max Planck Research School, University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), IDM/fMEG Center of the Helmholtz Center Munich at the University of Tübingen, University of Tübingen, Tübingen, Germany
| | - Sangyeob Baek
- Department of Neural Dynamics and Magnetoencephalography, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- MEG-Center, University of Tübingen, Tübingen, Germany
| | - Hui Chen
- Department of Neural Dynamics and Magnetoencephalography, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- MEG-Center, University of Tübingen, Tübingen, Germany
| | - Giulia Righetti
- Department of Neural Dynamics and Magnetoencephalography, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- MEG-Center, University of Tübingen, Tübingen, Germany
- Graduate Training Centre of Neuroscience, International Max Planck Research School, University of Tübingen, Tübingen, Germany
- Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Juergen Dax
- Department of Neural Dynamics and Magnetoencephalography, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- MEG-Center, University of Tübingen, Tübingen, Germany
| | - Cornelius Kronlage
- Department of Epileptology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Milena Kirchgässner
- Department of Epileptology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Alyssa Romano
- Department of Epileptology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Johanna Heilos
- Department of Epileptology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Deborah Staber
- Department of Epileptology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Julia Oppold
- Department of Epileptology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Thomas Middelmann
- Department of Biosignals, Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany
| | - Christoph Braun
- Department of Neural Dynamics and Magnetoencephalography, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- MEG-Center, University of Tübingen, Tübingen, Germany
- Center for Mind/Brain Sciences (CIMeC), University of Trento, Rovereto, Italy
- Department of Psychology and Cognitive Science (DiPsCo), University of Trento, Rovereto, Italy
| | - Philip Broser
- Children’s Hospital of Eastern Switzerland, Sankt Gallen, Switzerland
| | - Justus Marquetand
- Department of Neural Dynamics and Magnetoencephalography, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- MEG-Center, University of Tübingen, Tübingen, Germany
- Department of Epileptology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
- *Correspondence: Justus Marquetand,
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23
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Wittevrongel B, Holmes N, Boto E, Hill R, Rea M, Libert A, Khachatryan E, Van Hulle MM, Bowtell R, Brookes MJ. Practical real-time MEG-based neural interfacing with optically pumped magnetometers. BMC Biol 2021; 19:158. [PMID: 34376215 PMCID: PMC8356471 DOI: 10.1186/s12915-021-01073-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 04/25/2021] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Brain-computer interfaces decode intentions directly from the human brain with the aim to restore lost functionality, control external devices or augment daily experiences. To combine optimal performance with wide applicability, high-quality brain signals should be captured non-invasively. Magnetoencephalography (MEG) is a potent candidate but currently requires costly and confining recording hardware. The recently developed optically pumped magnetometers (OPMs) promise to overcome this limitation, but are currently untested in the context of neural interfacing. RESULTS In this work, we show that OPM-MEG allows robust single-trial analysis which we exploited in a real-time 'mind-spelling' application yielding an average accuracy of 97.7%. CONCLUSIONS This shows that OPM-MEG can be used to exploit neuro-magnetic brain responses in a practical and flexible manner, and opens up new avenues for a wide range of new neural interface applications in the future.
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Affiliation(s)
- Benjamin Wittevrongel
- Laboratory for Neuro- and Psychophysiology, Department of Neurosciences, KU Leuven, Leuven, Belgium. .,Leuven Institute for Artificial Intelligence (Leuven.AI), Leuven, Belgium. .,Leuven Brain Institute (LBI), Leuven, Belgium.
| | - Niall Holmes
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Elena Boto
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Ryan Hill
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Molly Rea
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Arno Libert
- Laboratory for Neuro- and Psychophysiology, Department of Neurosciences, KU Leuven, Leuven, Belgium.,Leuven Brain Institute (LBI), Leuven, Belgium
| | - Elvira Khachatryan
- Laboratory for Neuro- and Psychophysiology, Department of Neurosciences, KU Leuven, Leuven, Belgium.,Leuven Brain Institute (LBI), Leuven, Belgium
| | - Marc M Van Hulle
- Laboratory for Neuro- and Psychophysiology, Department of Neurosciences, KU Leuven, Leuven, Belgium.,Leuven Institute for Artificial Intelligence (Leuven.AI), Leuven, Belgium.,Leuven Brain Institute (LBI), Leuven, Belgium
| | - Richard Bowtell
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
| | - Matthew J Brookes
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, UK
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24
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Tang J, Yin Y, Zhai Y, Zhou B, Han B, Yang H, Liu G. Transient dynamics of atomic spin in the spin-exchange-relaxation-free regime. OPTICS EXPRESS 2021; 29:8333-8343. [PMID: 33820281 DOI: 10.1364/oe.418776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 02/17/2021] [Indexed: 06/12/2023]
Abstract
In this paper, we experimentally study transient dynamics of spin polarized atoms in the spin-exchange-relaxation-free (SERF) regime with a single-beam configuration. We pumped atoms with a weak detuning pumping beam, along with a sequence of magnetic field pulses orthogonal to the pumping beam were applied. The dynamics of atomic spin, which experiences Larmor precession under the perturbation of magnetic field, is detected by the transmitted pumping beam. Benefited from the long coherence time of atomic spin in the SERF regime, the dependence of precession frequency and decay rate, which is equal to the magnetic resonance linewidth of atomic spin, on magnetic fields is studied with the transient dynamics of atomic spin in the limit of low spin polarization. Moreover, we demonstrate that coil constants can be calibrated by analyzing the precession frequency of the transient dynamics of atomic spin. And the experimental results show that the coil constants are 114.25 ± 0.02 nT/mA and 114.12 ± 0.04 nT/mA in x- and y-axis, respectively. This method is particularly applicable to study the atomic spin dynamics and calibrate the coil constant in situ of a miniature single-beam SERF magnetometer.
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Bartin R, Maltret A, Nicloux M, Ville Y, Bonnet D, Stirnemann J. Outcomes of sustained fetal tachyarrhythmias after transplacental treatment. Heart Rhythm O2 2021; 2:160-167. [PMID: 34113918 PMCID: PMC8183966 DOI: 10.1016/j.hroo.2021.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Background Fetal tachyarrhythmia is a condition that may lead to cardiac dysfunction, hydrops, and death. Despite a transplacental treatment, failure to obtain or maintain sinus rhythm may occur. Objective We aimed to analyze the perinatal outcomes of sustained fetal tachyarrhythmias after in utero treatment. Methods We performed a retrospective evaluation of 69 cases with sustained fetal tachyarrhythmia. We compared the perinatal and long-term outcomes of prenatally converted and drug-resistant fetuses. Tachyarrhythmia subtypes were also evaluated. Results Conversion to sinus rhythm was obtained in 74% of cases; 26% of cases were drug-resistant and delivered arrhythmic. Three perinatal deaths occurred in both groups (6.7% vs 17%, P = .34). Neonates delivered arrhythmic were more frequently admitted to neonatal intensive care units (75% vs 31%, P < .01), and their hospital stay was longer (20.9 vs 6.64 days, P < .001). Multiple neonatal recurrences (81% vs 11%, P < .001), temporary hemodynamic dysfunction or heart failure (50% vs 6.7%, P < .001), and postnatal use of a combination treatment (44% vs 13%, P = .028) were also more frequent in this population. Beyond the neonatal period, rates of recurrences within the first 16 months were higher in drug-resistant fetuses (HR = 16.14, CI 95% [4.485; 193.8], P < .001). In this population, postnatal electrocardiogram revealed an overrepresentation of rare mechanisms, especially permanent junctional reciprocating tachycardia (PJRT) (31%). Conclusion Prenatal conversion to stable sinus rhythm is a major determinant of perinatal and long-term outcomes in fetal tachyarrhythmias. The underlying electrophysiological mechanisms have a major role in predicting these differential outcomes with an overrepresentation of PJRT in the drug-resistant population.
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Affiliation(s)
- Raphael Bartin
- Obstetric and Maternal Fetal Medicine and EA7328.,Hôpital universitaire Necker-Enfants malades, AP-HP
| | - Alice Maltret
- M3C-Necker, Pediatric and Congenital Cardiology Unit.,Hôpital universitaire Necker-Enfants malades, AP-HP
| | - Muriel Nicloux
- Neonatology and Neonatal Intensive Care Unit.,Hôpital universitaire Necker-Enfants malades, AP-HP
| | - Yves Ville
- Obstetric and Maternal Fetal Medicine and EA7328.,Hôpital universitaire Necker-Enfants malades, AP-HP.,Université de Paris, Paris, France
| | - Damien Bonnet
- M3C-Necker, Pediatric and Congenital Cardiology Unit.,Hôpital universitaire Necker-Enfants malades, AP-HP.,Université de Paris, Paris, France
| | - Julien Stirnemann
- Obstetric and Maternal Fetal Medicine and EA7328.,Hôpital universitaire Necker-Enfants malades, AP-HP.,Université de Paris, Paris, France
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Silva M, Franco F, Leitao DC, Cardoso S, Freitas PP. Two-dimensional arrays of vertically packed spin-valves with picoTesla sensitivity at room temperature. Sci Rep 2021; 11:215. [PMID: 33420189 PMCID: PMC7794481 DOI: 10.1038/s41598-020-79856-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 12/08/2020] [Indexed: 11/09/2022] Open
Abstract
A new device architecture using giant magnetoresistive sensors demonstrates the capability to detect very low magnetic fields on the pT range. A combination of vertically packed spin-valve sensors with two-dimensional in-plane arrays, connected in series and in parallel, delivers a final detection level of 360 pT/[Formula: see text] at 10 Hz at room temperature. The device design is supported by an analytical model developed for a vertically packed spin-valve system, which takes into account all magnetic couplings present. Optimization concerning the spacer thickness and sensor physical dimensions depending on the number of pilled up spin-valves is necessary. To push the limits of detection, arrays of a large number of sensing elements (up to 440,000) are patterned with a geometry that improves sensitivity and in a configuration that reduces the resistance, leading to a lower noise level. The final device performance with pT detectivity is demonstrated in an un-shielded environment suitable for detection of bio-signals.
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Affiliation(s)
- Marilia Silva
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC-MN), 1000-029, Lisbon, Portugal. .,Instituto Superior Tecnico (IST), Universidade de Lisboa, 1040-001, Lisbon, Portugal.
| | - Fernando Franco
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC-MN), 1000-029, Lisbon, Portugal.,Instituto Superior Tecnico (IST), Universidade de Lisboa, 1040-001, Lisbon, Portugal.,Analog Devices, Limerick, V94 RT99, Ireland
| | - Diana C Leitao
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC-MN), 1000-029, Lisbon, Portugal.,Instituto Superior Tecnico (IST), Universidade de Lisboa, 1040-001, Lisbon, Portugal
| | - Susana Cardoso
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC-MN), 1000-029, Lisbon, Portugal.,Instituto Superior Tecnico (IST), Universidade de Lisboa, 1040-001, Lisbon, Portugal
| | - Paulo P Freitas
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC-MN), 1000-029, Lisbon, Portugal.,INL - International Iberian Nanotechnology Laboratory, 4715-330, Braga, Portugal
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Escalona-Vargas D, Bolin EH, Lowery CL, Siegel ER, Eswaran H. Recording and quantifying fetal magnetocardiography signals using a flexible array of optically-pumped magnetometers. Physiol Meas 2021; 41:125003. [PMID: 33086201 PMCID: PMC7875519 DOI: 10.1088/1361-6579/abc353] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Fetal magnetocardiography (fMCG) is a non-invasive biomagnetic technique that provides detailed beat-to-beat fetal heart rate analysis, both in normal rhythm as well as in fetal arrhythmias. New cryogenic-free sensors called optically pumped magnetometers (OPMs) have emerged as a less expensive and more geometrically flexible alternative to traditional Superconducting Quantum Interference Device (SQUID) technology for performing fMCG. The objective of the study was to show the ability of OPMs to record fMCG using flexible geometry while seeking to preserve signal quality, and to quantify fetal heart rate variability (FHRV). APPROACH Biomagnetic measurements were performed with OPMs in 24 healthy pregnant women with uncomplicated singleton pregnancies between 28 and 38 weeks gestation (GA). A total of 96 recordings were analyzed from OPM data that was collected using sensors placed in two different maternal configurations over the abdomen. The fMCG signals were extracted and the quality of the recordings were quantified by peak amplitudes and signal-to-noise ratio (SNR). R peaks were used to perform both time and frequency domain FHRV analysis. FHRV measures obtained from OPMs were compared descriptively to the same measures obtained from GA-matched existing SQUID data. MAIN RESULTS The fMCG derived from OPMs were observed in 21 of the 24 participants. Higher detection rates (85%) of fMCG signals were observed in the data sets recorded at GA >32 weeks. Peak amplitudes and SNR values were similar between two maternal configurations, but peak amplitudes were significantly higher (p = 0.013) in late GA compared to early GA. FHRV indicators were successfully extracted and their values overlapped substantially with those obtained from SQUID recordings. SIGNIFICANCE Taking advantage of the geometric flexibility of the OPMs, we have demonstrated their ability to record and quantify fMCG in different maternal positions as opposed to rigid SQUID configurations.
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Affiliation(s)
- Diana Escalona-Vargas
- Department of Pediatrics, Division of Neurology, University of Arkansas for Medical Sciences, Arkansas Children’s Hospital, Little Rock, AR, USA
- Department of Obstetrics and Gynecology, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Elijah H. Bolin
- Department of Pediatrics, Division of Cardiology, University of Arkansas for Medical Sciences, Arkansas Children’s Hospital, Little Rock, AR, USA
| | - Curtis L. Lowery
- Department of Obstetrics and Gynecology, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Eric R. Siegel
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Hari Eswaran
- Department of Obstetrics and Gynecology, University of Arkansas for Medical Sciences, Little Rock, AR
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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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Jodko-Władzińska A, Wildner K, Pałko T, Władziński M. Compensation System for Biomagnetic Measurements with Optically Pumped Magnetometers inside a Magnetically Shielded Room. SENSORS (BASEL, SWITZERLAND) 2020; 20:E4563. [PMID: 32823964 PMCID: PMC7471992 DOI: 10.3390/s20164563] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/11/2020] [Accepted: 08/12/2020] [Indexed: 11/16/2022]
Abstract
Magnetography with superconducting quantum interference device (SQUID) sensor arrays is a well-established technique for measuring subtle magnetic fields generated by physiological phenomena in the human body. Unfortunately, the SQUID-based systems have some limitations related to the need to cool them down with liquid helium. The room-temperature alternatives for SQUIDs are optically pumped magnetometers (OPM) operating in spin exchange relaxation-free (SERF) regime, which require a very low ambient magnetic field. The most common two-layer magnetically shielded rooms (MSR) with residual magnetic field of 50 nT may not be sufficiently magnetically attenuated and additional compensation of external magnetic field is required. A cost-efficient compensation system based on square Helmholtz coils was designed and successfully used for preliminary measurements with commercially available zero-field OPM. The presented setup can reduce the static ambient magnetic field inside a magnetically shielded room, which improves the usability of OPMs by providing a proper environment for them to operate, independent of initial conditions in MSR.
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Affiliation(s)
- Anna Jodko-Władzińska
- Warsaw University of Technology, Faculty of Mechatronics, Institute of Metrology and Biomedical Engineering, Boboli 8 St, 02-525 Warsaw, Poland; (K.W.); (T.P.); (M.W.)
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Schellpfeffer MA, Strasburger JF, Baffa O, Strand SA, Lutter W, Phan T, Wakai RT. Dynamics of the use of magnetocardiography in the study of the cardiac conduction system of the chick embryo. Birth Defects Res 2020; 112:1825-1833. [PMID: 32790153 DOI: 10.1002/bdr2.1777] [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: 05/14/2020] [Revised: 06/24/2020] [Accepted: 07/09/2020] [Indexed: 01/02/2023]
Abstract
INTRODUCTION Human fetal magnetocardiography (fMCG) has been done for several decades to evaluate fetal arrhythmias using a superconducting quantum interference device (SQUID) magnetometer, but there is little work in embryonic/fetal animal models. This study uses an optically-pumped magnetometer (OPM) to obtain an fMCG in the chick embryo. METHODS White Leghorn chick embryos were examined from incubation Day #10-19. Different examination chambers were tested to optimize embryonic thermal stability and magnetic signal acquisition. All examinations were done with magnetic shielding. The OPM sensors were placed next to the egg shell. The embryo's position was localized by transilluminating the intact egg or ultrasound imaging the egg with an open air cell to optimize sensor placement. The raw data for each embryo was postprocessed to obtain a fMCG composite waveform. RESULTS fMCG's were obtained in embryos from Day #12 to 19. The best success with intact eggs was obtained using five sensors; one at the bottom and four around the lower perimeter of the egg at 90° intervals with the egg oriented vertically and the air cell up. Using ultrasound imaging with the air cell open only two sensors were necessary, one at the bottom and one laterally next to the embryo. fMCGs were analyzed for heart rate and rhythm, each portion of the PQRST waveform, and the PR interval, QRS complex, RR interval, and QT interval. CONCLUSIONS This study validates the chick embryo as an animal model to study in a longitudinal and noninvasive fashion the fetal cardiac conduction system by using OPM magnetocardiography.
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Affiliation(s)
- Michael A Schellpfeffer
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Janette F Strasburger
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | | | - Sarah A Strand
- University of Wisconsin-Madison, Madison, Wisconsin, USA.,University of Iowa Iowa City, Iowa City, Iowa, USA
| | - William Lutter
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Tan Phan
- University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Ronald T Wakai
- University of Wisconsin-Madison, Madison, Wisconsin, USA
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Fescenko I, Jarmola A, Savukov I, Kehayias P, Smits J, Damron J, Ristoff N, Mosavian N, Acosta VM. Diamond magnetometer enhanced by ferrite flux concentrators. PHYSICAL REVIEW RESEARCH 2020; 2:023394. [PMID: 33117992 PMCID: PMC7591154 DOI: 10.1103/physrevresearch.2.023394] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Magnetometers based on nitrogen-vacancy (NV) centers in diamond are promising room-temperature, solid-state sensors. However, their reported sensitivity to magnetic fields at low frequencies (≾1 kHz) is presently ≿10 pT s1/2, precluding potential applications in medical imaging, geoscience, and navigation. Here we show that high-permeability magnetic flux concentrators, which collect magnetic flux from a larger area and concentrate it into the diamond sensor, can be used to improve the sensitivity of diamond magnetometers. By inserting an NV-doped diamond membrane between two ferrite cones in a bowtie configuration, we realize a ~250-fold increase of the magnetic field amplitude within the diamond. We demonstrate a sensitivity of ~0.9 pT s1/2 to magnetic fields in the frequency range between 10 and 1000 Hz. This is accomplished using a dual-resonance modulation technique to suppress the effect of thermal shifts of the NV spin levels. The magnetometer uses 200 mW of laser power and 20 mW of microwave power. This work introduces a new degree of freedom for the design of diamond sensors by using structured magnetic materials to manipulate magnetic fields.
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Affiliation(s)
- Ilja Fescenko
- Center for High Technology Materials and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87106, USA
| | - Andrey Jarmola
- ODMR Technologies Inc., El Cerrito, California 94530, USA
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Igor Savukov
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Pauli Kehayias
- Center for High Technology Materials and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87106, USA
- Sandia National Laboratory, Albuquerque, New Mexico 87185, USA
| | - Janis Smits
- Center for High Technology Materials and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87106, USA
- Laser Center of the University of Latvia, Riga LV-1004, Latvia
| | - Joshua Damron
- Center for High Technology Materials and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87106, USA
| | - Nathaniel Ristoff
- Center for High Technology Materials and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87106, USA
| | - Nazanin Mosavian
- Center for High Technology Materials and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87106, USA
| | - Victor M. Acosta
- Center for High Technology Materials and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87106, USA
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Strand S, Strasburger JF, Cuneo BF, Wakai RT. Complex and Novel Arrhythmias Precede Stillbirth in Fetuses With De Novo Long QT Syndrome. Circ Arrhythm Electrophysiol 2020; 13:e008082. [PMID: 32421437 DOI: 10.1161/circep.119.008082] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Long QT syndrome (LQTS) is a leading cause of sudden cardiac death in early life and has been implicated in ≈10% of sudden infant deaths and unexplained stillbirths. The purpose of our study was to use fetal magnetocardiography to characterize the electrophysiology and rhythm phenotypes of fetuses with de novo and inherited LQTS variants and identify risk factors for sudden death before birth. METHODS We reviewed the fetal magnetocardiography database from the University of Wisconsin Biomagnetism Laboratory for fetuses with confirmed LQTS. We assessed waveform intervals, heart rate, and rhythm, including the signature LQTS rhythms: functional 2° atrioventricular block, T-wave alternans, and torsade de pointes (TdP). RESULTS Thirty-nine fetuses had pathogenic variants in LQTS genes: 27 carried the family variant, 11 had de novo variants, and 1 was indeterminate. De novo variants, especially de novo SCN5A variants, were strongly associated with a severe rhythm phenotype and perinatal death: 9 (82%) showed signature LQTS rhythms, 6 (55%) showed TdP, 5 (45%) were stillborn, and 1 (9%) died in infancy. Those that died exhibited novel fetal rhythms, including atrioventricular block with 3:1 conduction ratio, QRS alternans in 2:1 atrioventricular block, long-cycle length TdP, and slow monomorphic ventricular tachycardia. Premature ventricular contractions were also strongly associated with TdP and perinatal death. Fetuses with familial variants showed a lower incidence of signature LQTS rhythm (6/27=22%), including TdP (3/27=11%). All were live born. CONCLUSIONS The malignancy of de novo LQTS variants was remarkably high and demonstrate that these mutations are a significant cause of stillbirth. Their ability to manifest rhythms not known to be associated with LQTS increases the difficulty of echocardiographic diagnosis and decreases the likelihood that a resultant fetal loss is attributed to LQTS. Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT03047161.
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Affiliation(s)
- Sarah Strand
- Department of Medical Physics, University of Wisconsin-Madison (S.S. R.T.W.)
| | - Janette F Strasburger
- Division of Cardiology, Department of Pediatrics, Children's Hospital of Wisconsin, Medical College of Wisconsin, Milwaukee (J.F.S.)
| | - Bettina F Cuneo
- Division of Cardiology, Department of Pediatrics (B.F.C.), Children's Hospital Colorado & University of Colorado School of Medicine, Aurora.,The Colorado Fetal Care Center (B.F.C), Children's Hospital Colorado & University of Colorado School of Medicine, Aurora
| | - Ronald T Wakai
- Department of Medical Physics, University of Wisconsin-Madison (S.S. R.T.W.)
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Widatalla N, Kasahara Y, Kimura Y, Khandoker A. Model based estimation of QT intervals in non-invasive fetal ECG signals. PLoS One 2020; 15:e0232769. [PMID: 32392232 PMCID: PMC7213701 DOI: 10.1371/journal.pone.0232769] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 04/21/2020] [Indexed: 11/18/2022] Open
Abstract
The end timing of T waves in fetal electrocardiogram (fECG) is important for the evaluation of ST and QT intervals which are vital markers to assess cardiac repolarization patterns. Monitoring malignant fetal arrhythmias in utero is fundamental to care in congenital heart anomalies preventing perinatal death. Currently, reliable detection of end of T waves is possible only by using fetal scalp ECG (fsECG) and fetal magnetocardiography (fMCG). fMCG is expensive and less accessible and fsECG is an invasive technique available only during intrapartum period. Another safer and affordable alternative is the non-invasive fECG (nfECG) which can provide similar assessment provided by fsECG and fMECG but with less accuracy (not beat by beat). Detection of T waves using nfECG is challenging because of their low amplitudes and high noise. In this study, a novel model-based method that estimates the end of T waves in nfECG signals is proposed. The repolarization phase has been modeled as the discharging phase of a capacitor. To test the model, fECG signals were collected from 58 pregnant women (age: (34 ± 6) years old) bearing normal and abnormal fetuses with gestational age (GA) 20-41 weeks. QT and QTc intervals have been calculated to test the level of agreement between the model-based and reference values (fsECG and Doppler Ultrasound (DUS) signals) in normal subjects. The results of the test showed high agreement between model-based and reference values (difference < 5%), which implies that the proposed model could be an alternative method to detect the end of T waves in nfECG signals.
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Affiliation(s)
- Namareq Widatalla
- Next Generation Biological Information Technology, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan
- * E-mail:
| | - Yoshiyuki Kasahara
- Next Generation Biological Information Technology, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan
- Advanced Interdisciplinary Biomedical Engineering, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yoshitaka Kimura
- Next Generation Biological Information Technology, Tohoku University Graduate School of Biomedical Engineering, Sendai, Japan
- Advanced Interdisciplinary Biomedical Engineering, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Ahsan Khandoker
- Healthcare Engineering Innovation Center (HEIC), Department of Biomedical Engineering, Khalifa University, Abu Dhabi, UAE
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Murzin D, Mapps DJ, Levada K, Belyaev V, Omelyanchik A, Panina L, Rodionova V. Ultrasensitive Magnetic Field Sensors for Biomedical Applications. SENSORS (BASEL, SWITZERLAND) 2020; 20:E1569. [PMID: 32168981 PMCID: PMC7146409 DOI: 10.3390/s20061569] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 03/02/2020] [Accepted: 03/06/2020] [Indexed: 12/27/2022]
Abstract
The development of magnetic field sensors for biomedical applications primarily focuses on equivalent magnetic noise reduction or overall design improvement in order to make them smaller and cheaper while keeping the required values of a limit of detection. One of the cutting-edge topics today is the use of magnetic field sensors for applications such as magnetocardiography, magnetotomography, magnetomyography, magnetoneurography, or their application in point-of-care devices. This introductory review focuses on modern magnetic field sensors suitable for biomedicine applications from a physical point of view and provides an overview of recent studies in this field. Types of magnetic field sensors include direct current superconducting quantum interference devices, search coil, fluxgate, magnetoelectric, giant magneto-impedance, anisotropic/giant/tunneling magnetoresistance, optically pumped, cavity optomechanical, Hall effect, magnetoelastic, spin wave interferometry, and those based on the behavior of nitrogen-vacancy centers in the atomic lattice of diamond.
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Affiliation(s)
- Dmitry Murzin
- Institute of Physics, Mathematics and Information Technology, Immanuel Kant Baltic Federal University, 236041 Kaliningrad, Russia; (K.L.); (V.B.); (A.O.); (L.P.); (V.R.)
| | - Desmond J. Mapps
- Faculty of Science and Engineering, University of Plymouth, Plymouth PL4 8AA, UK;
| | - Kateryna Levada
- Institute of Physics, Mathematics and Information Technology, Immanuel Kant Baltic Federal University, 236041 Kaliningrad, Russia; (K.L.); (V.B.); (A.O.); (L.P.); (V.R.)
| | - Victor Belyaev
- Institute of Physics, Mathematics and Information Technology, Immanuel Kant Baltic Federal University, 236041 Kaliningrad, Russia; (K.L.); (V.B.); (A.O.); (L.P.); (V.R.)
| | - Alexander Omelyanchik
- Institute of Physics, Mathematics and Information Technology, Immanuel Kant Baltic Federal University, 236041 Kaliningrad, Russia; (K.L.); (V.B.); (A.O.); (L.P.); (V.R.)
| | - Larissa Panina
- Institute of Physics, Mathematics and Information Technology, Immanuel Kant Baltic Federal University, 236041 Kaliningrad, Russia; (K.L.); (V.B.); (A.O.); (L.P.); (V.R.)
- National University of Science and Technology, MISiS, 119049 Moscow, Russia
| | - Valeria Rodionova
- Institute of Physics, Mathematics and Information Technology, Immanuel Kant Baltic Federal University, 236041 Kaliningrad, Russia; (K.L.); (V.B.); (A.O.); (L.P.); (V.R.)
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Strand S, Lutter W, Strasburger JF, Shah V, Baffa O, Wakai RT. Low-Cost Fetal Magnetocardiography: A Comparison of Superconducting Quantum Interference Device and Optically Pumped Magnetometers. J Am Heart Assoc 2019; 8:e013436. [PMID: 31394997 PMCID: PMC6759914 DOI: 10.1161/jaha.119.013436] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background Fetal magnetocardiography (fMCG) is a highly effective technique for evaluation of fetuses with life-threatening arrhythmia, but its dissemination has been constrained by the high cost and complexity of Superconducting Quantum Interference Device (SQUID) instrumentation. Optically pumped magnetometers (OPMs) are a promising new technology that can replace SQUIDs for many applications. This study compares the performance of an fMCG system, utilizing OPMs operating in a person-sized magnetic shield, to that of a conventional fMCG system, utilizing SQUID magnetometers operating in a magnetically shielded room. Methods and Results fMCG recordings were made in 24 subjects using the SQUID system with the mother lying supine in a magnetically shielded room and the OPM system with the mother lying prone in a person-sized, cylindrical shield. Signal-to-noise ratios of the OPM and SQUID recordings were not statistically different and were adequate for diagnostic purposes with both technologies. Although the environmental noise was higher using the small open-ended shield, this was offset by the higher signal amplitude achieved with prone positioning, which reduced the distance between the fetus and sensors and improved patient comfort. In several subjects, fMCG provided a differential diagnosis that was more precise and/or definitive than was possible with echocardiography alone. Conclusions The OPM-based system was portable, improved patient comfort, and performed as well as the SQUID-based system at a small fraction of the cost. Electrophysiological assessment of fetal rhythm is now practical and will have a major impact on management of fetuses with long QT syndrome and other life-threatening arrhythmias.
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Affiliation(s)
- Sarah Strand
- Department of Medical Physics University of Wisconsin Madison WI
| | - William Lutter
- Department of Medical Physics University of Wisconsin Madison WI
| | - Janette F Strasburger
- Division of Cardiology Department of Pediatrics Children's Hospital of Wisconsin- Milwaukee Milwaukee WI
| | | | - Oswaldo Baffa
- Department of Physics FFCLRP Ribeirao Preto, University of Sao Paulo Brazil
| | - Ronald T Wakai
- Department of Medical Physics University of Wisconsin Madison WI
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