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Chinese Physics B 2022年第7期31卷 229-234页

作者： Kang Yang Hong-Wei Zhang Qian-Nian Zhang Jun-Jun Zha Deng-Chao Huang College of Electrical Engineering Anhui Polytechnic UniversityWuhu 241000China Key Laboratory of Advanced Perception and Intelligent Control of High-end Equipment Ministry of EducationAnhui Polytechnic UniversityWuhu 241000China

For a magnetocardiography(MCG)system inside a magnetically shielded room(MSR),the residual field should be further suppressed to obtain high-quality MCG *** this paper,a compensation system has been developed based on the bi-planar coil and the proportional-integral-derivative(PID)*** bi-planar coil,derived from the target-field theory and the Tikhonov regularization method,is utilized to generate magnetic field with high uniformity in the predefined target *** the PID controller is introduced to provide dynamic compensation current for the coil,according to the residual field change monitored by a reference SQUID *** measurement results show that the noise suppression ratio(NSR)can reach above 20 dB in the low-frequency range from 0.1 Hz to 50 *** DC component and the fluctuation of the residual field in time-domain can be respectively suppressed to 0 p T and 4 p T,indicating that this proposed compensation method is useful for the MCG measurement.

关键词： SQUID magnetocardiography bi-planar coil active compensation

Baseline optimization of SQUID gradiometer for magnetocardiography

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Chinese Physics B 2015年第2期24卷 471-473页

作者：李华张树林邱阳张永升张朝祥孔祥燕谢晓明 State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology(SIMIT)Chinese Academy of Sciences(CAS) Joint Research Laboratory on Superconductivity and Bioelectronics Collaboration Between CAS-Shanghai University of Chinese Academy of Sciences

SQUID gradiometer techniques are widely used in noise cancellation for biomagnetic *** appropriate gradiometer baseline is very important for the biomagnetic detection with high *** placing several magnetometers at different heights along the vertical direction,we could simultaneously obtain the synthetic gradiometers with different *** using the traditional signal-to-noise ratio（SNR） as a performance index,we successfully obtain an optimal baseline for the magnetocardiography（MCG） measurement in a magnetically shielded room（MSR）.Finally,we obtain an optimal baseline of 7 cm and use it for the practical MCG measurement in our *** SNR about 38 dB is obtained in the recorded MCG signal.

关键词： SQUID gradiometer baseline optimization magnetocardiography

magnetocardiography capabilities in myocardium injuries diagnosis

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World Journal of Cardiovascular Diseases 2013年第5期3卷 380-388页

作者： V. Sosnytskyy I. Chaikovsky L. Stadnyuk G. Miasnykov A. Kazmirchyk T. Sosnytska O. Gurjeva General Military-Medical Clinical Center Kiev Ukraine National Scientific Center M. D. Strajesko Institute of Cardiology Academy of Medical Sciences of Ukraine Kiev Ukraine P. L. Shupik National Medical Academy of Postgraduate Education Kiev Ukraine

Objective: The electrophysiological properties of the myocardium are extremely heterogeneous. Verification of new magnetocardiography (MCG) signs appears an important aspect for severity assessment of ischemic myocardium damage, ischemic heart disease (IHD) course prognosis, determining of indications for preventive “aggressive” therapy and estimation of its efficacy in patients with IHD. The objective of this research was the investigation of magnetocardiography (MCG) capabilities in diagnosis of ischemic and inflammatory myocardial injuries using new MCG markers of the spatiotemporal organization of myocardium excitation. Methods and results: There were 128 patients examined in three groups. Group 1 contained 34 healthy volunteers. Group 2 contained 62 patients with IHD diagnosis. Group 3 included 32 comparatively young patients with acute myocarditis diagnosis. MCG-mapping of patients was performed at rest on the 7-channel MCG-scanners “Cardiomagscan” V 3.1 (Company KMG, Ukraine) in non-shielded MCG laboratory. 11 MCG markers were determined for selected time intervals of the cardiac cycle. Obtained data provided evidences about significant differences in values of proposed MCG markers for various groups. In patients with AMI, rate of parameters change is higher than without AMI (Sub-groups 2.1 and 2.2 differ by 8 MCG markers). Patients of 2nd and 3rd groups are different from healthy patients by 8 of 11 markers. Analysis of the obtained data has demonstrated good capabilities of MCG in differential diagnostics. Application of discriminatory analysis allowed us to get classification functions, which could be used (with 82% accuracy) to qualify the just examined patient to the investigated categories. Conclusion: Based on the new methodological approach during the studies, the most informative MCG-criteria of space-temporal organization of myocardium excitation in patients with IHD has been proposed. The method is able to distinguish healthy subjects and myocardit

关键词： Transmural Electric Heterogeneity magnetocardiography Myocardial Ischemia Myocarditis Differential Diagnostics

Low-T_c direct current superconducting quantum interference device magnetometer-based 36-channel magnetocardiography system in a magnetically shielded room

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Chinese Physics B 2015年第7期24卷 590-594页

作者：邱阳李华张树林王永良孔祥燕张朝祥张永升徐小峰杨康谢晓明 State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences Joint Research Laboratory on Superconductivity and Bioelectronics Collaboration between Chinese Academy of Sciences–Shanghai University of Chinese Academy of Sciences

We constructed a 36-channel magnetocardiography（MCG） system based on low-Tc direct current（DC） superconducting quantum interference device（SQUID） magnetometers operated inside a magnetically shielded room（MSR）. Weakly damped SQUID magnetometers with large Steward–Mc Cumber parameter βc（βc≈ 5）, which could directly connect to the operational amplifier without any additional feedback circuit, were used to simplify the readout electronics. With a flux-to-voltage transfer coefficient V / Φ larger than 420 μV/Φ0, the SQUID magnetometers had a white noise level of about 5.5 f T·Hz-1/2when operated in MSR. 36 sensing magnetometers and 15 reference magnetometers were employed to realize software gradiometer configurations. The coverage area of the 36 sensing magnetometers is 210×210 mm2. MCG measurements with a high signal-to-noise ratio of 40 d B were done successfully using the developed system.

关键词： superconducting quantum interference devices magnetometer magnetocardiography noise can-cellation

A complementary least-mean-square algorithm of adaptive filtering for SQUID based magnetocardiography

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Chinese Physics B 2005年第6期14卷 1095-1100页

作者：李倬陈赓华张利华杨乾声冯稷 InstituteofPhysics ChineseacademyofSciencesBeijing100080China

We present acomplementary least-mean-square algorithm of adaptive filtering for SQUID-based magnetocardiography, in which both rapid convergence and fine tracking are realized by switching the weight parameters back a... 详细信息

关键词： magnetocardiography convergence tracking

A normalized data-reusing least-mean-square algorithm of noise cancellation for magnetocardiography

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Chinese Physics B 2004年第11期13卷 1820-1825页

作者：孔祥燕王会武田野黄旭光张利华任育峰陈赛华杨乾声 InstituteofPhysics ChineseAcademyofSciencesBeijing100080China

An adaptive filter based on Data-Reusing Least-Mean-Square algorithm has been proposed and applied in magnetocardiography (MCG) to suppress ambient noise. Numerical simulation studies indicate that the adaptive filter is a powerful noise suppresser for correlated interferences, especially for those with amplitude changing and time *** the filter has a wide frequency bandwidth. With this filter, the signal-to-noise ratio of an MCG is improved to the intrinsic noise level. The periodic average method for further improvement of the noise level in MCG is also discussed.

关键词： magnetocardiography noise suppression

A digital filtering scheme for SQUID based magnetocardiography

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Chinese Physics B 2006年第1期15卷 100-103页

作者：朱学敏任育峰于洪伟赵士平陈庚华张利华杨乾声 Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China

Considering the properties of slow change and quasi-periodicity of magnetocardiography （MCG） signal, we use an integrated technique of adaptive and low-pass filtering in dealing with two-channel MCG data measured by high Tc SQUIDs. The adaptive filter in the time domain is based on a noise feedback normalized least-mean-square （NLMS） algorithm, and the low-pass filter with a cutoff at 100Hz in the frequeucy domain characterized by Caussian functions is combined with a notch at the power line frequency. In this way, both relevant and irrelevant noises in original MCG data are largely eliminated. The method may also be useful for other slowly varying quasi-periodical signals.

关键词： SQUIDs adaptive filter magnetocardiography

Measurement of T wave in magnetocardiography using tunnel magnetoresistance sensor

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Chinese Physics B 2023年第2期32卷 5-10页

作者：陆知宏纪帅杨建中 Department of Precision Instrument Tsinghua UniversityBeijing 100084China Beijing Innovation Center for Future Chips Beijing 100084China State Key Laboratory of Precision Measurement Technology and Instruments Tsinghua UniversityBeijing 100084China

Several critical clinical applications of magnetocardiography(MCG)involve its T *** T wave’s accuracy directly affects the diagnostic accuracy of MCG for ischemic heart disease and *** magnetoresistance(TMR)attracts attention as a new MCG measurement ***,the T waves measured by TMR are often drowned in *** accuracy of T waves needs to be discussed to determine the clinical value of MCG measured by *** study uses an improved empirical mode decomposition(EMD)algorithm and averaging to eliminate the noise in the MCG measured by *** MCG signals measured by TMR are compared with MCG measured by the optically pumped magnetometer(OPM)to judge its *** the MCG measured by OPM as a reference,the relative errors in time and amplitude of the T wave measured by TMR are 3.4%and 1.8%,*** is the first demonstration that TMR can accurately measure the time and amplitude of MCG T *** ability to provide reliable T wave data illustrates the significant clinical application value of TMR in MCG measurement.

关键词： magnetocardiography tunnel magnetoresistance optically pumped magnetometer T wave detection

Diagnostic value of magnetocardiography in patients with coronary heart disease and in-stent restenosis

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Chinese Medical Journal 2008年第1期121卷 22-26页

作者： QUAN Wei-wei LU Guo-ping QI Wen-hang LI Ying-mei SHEN Yue YUAN Rong Department of Cardiology Rui Jin Hospital Medical College ofShanghai Jiao Tong University Shanghai 200025 China Shanghai Putuo District Center Hospital Shanghai 200062 China

Background In-stent restenosis （ISR） has become one of the most challenging problems in patients with coronary heart disease. At present, using non-invasive methods to assess ISR is a hot topic. In this investigation we attempted to explore the potential of magnetocardiography （MCG） in diagnosis of in-stent restenosis. Methods MCG was analyzed in 52 patients with coronary artery disease for three times： before stenting, one month and 7 months after successful intracoronary stenting. Results The average classification of total maps （ACTM） and the ratio of abnormal maps （RAM） were lower in 1 month after intracoronary stenting compared with that obtained before stent planting （2.91 vs 2.52, 65.74% vs 42.80%, P〈0.01）, while complex ventricular excitation index （CVEI） increased from -42.63 to -20.05 （P〈0.01）. In ISR subgroup （n=16）, RAM decreased in 1 month after intracoronary stenting compared to it before stenting （68.99% vs 45.26%, P〈0.05）. ACTM increased in 7 months compared to that obtained in 1 month after stenting （3.15 vs 2.51, P〈0.05）. According to the ROC curve, ACTM showed its unique diagnostic value in restenosis patients. The sensitivity and specificity of ACTM were 80.0%, 69.40%, respectively. Its positive predictive value and negative predictive value were 54.6% and 88.5%, respectively. Conclusions After successful intracoronary stenting, most parameters of MCG were improved. ACTM was of prognostic value in diagnosing ISR.

关键词： magnetocardiography magnetic field map current density map coronary heart disease intracoronary stenting

Inverse computation for cardiac sources using single current dipole and current multipole models

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Chinese Physics B 2009年第12期18卷 5566-5574页

作者：王倩马平陆宏唐雪正华宁唐发宽 Department of Physics State Key Laboratory for Artificial Microstructure and Mesoscopic PhysicsPeking University Department of Cardiology the 309th Hospital of PLA

Two cardiac functional models are constructed in this paper. One is a single current model and the other is a current multipole model. Parameters denoting the properties of these two models are calculated by a least-square fit to the measurements using a simulated annealing algorithm. The measured signals are detected at 36 observation nodes by a superconducting quantum interference device （SQUID）. By studying the trends of position, orientation and magnitude of the single current dipole model and the current multipole model in the QRS complex during one time span and comparing the reconstructed magnetocardiography （MCG） of these two cardiac models, we find that the current multipole model is a more appropriate model to represent cardiac electrophysiological activity.

关键词： magnetocardiography inverse computation cardiac source model