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2019 Vol. 38, No. 6 Published: 2019-12-20

Communications Regular Papers Invited Rreview Rreviews

Invited Rreview

	641	Wearable ECG: History, Key Technologies and Future Challenges
		Liu Chengyu, Yang Meicheng, Di Jianan, Xing Yantao, Li Yuwen, Li Jianqing
		DOI: 10.3969/j.issn.0258-8021.2019.06.001
		With the rapid development of Internet of things (IoT), big data, cloud computing, artificial intelligence (AI) and other advanced technologies, dynamic ECG monitoring has made remarkable progress towards the direction of wearable, intelligent and convenient in recent years. Wearable ECG device can facilitate the individualized, real-time, long-term and continuous monitoring of ECG data, providing an important carrier and technical means for the new mode of smart healthcare. This paper firstly summarized the basic concept and development history of wearable ECG, and then reviewed the related key technologies and typical wearable ECG devices. Finally, the perspectives and challenges of wearable ECG are analyzed.
		2019 Vol. 38 (6): 641-652 [Abstract] ( 1167 ) HTML (1 KB) PDF (5131 KB) ( 1438 )

Regular Papers

	653	Auto-Weighted Centralized Multi-Task Learning for Early MildCognitive Impairment Diagnosis
		Cheng Nina, Xiao Xiaohua, Hu Huoyou, Yang Peng, Wang Tianfu, Lei Baiying
		DOI: 10.3969/j.issn.0258-8021.2019.06.002
		Mild cognitive impairment (MCI) is the early stage of Alzheimer′s disease (AD) and is the best time for the diagnosis of the disease. By using multi-modal data one can comprehensively analyze the condition of the disease, which is conducive to the accurate diagnosis of the disease. However, the existing methods cannot effectively analyze the relationship between multiple modal data at the same time, and cannot effectively combine the advantages between functional state data and structural state data. For this reason, this paper proposed an auto-weighted centralized multi-task learning method for the diagnosis of MCI. The method can simultaneously learn data of different modalities and effectively combine the advantages between data. Specifically, firstly, brain networks were constructed for functional state data rs-fMRI and structural state data DTI respectively. Secondly, a new multi-task feature learning model was designed based on multi-modal data. The balance between the importance of each task and the modalities was automatically learned, including the similarity and specificity between different modalities, to obtain stable and discriminative expression features. Finally, the selected features were input into support vector machine (SVM) model for classification diagnosis. The experiments in this paper are based on the public database of the ADNI (Alzheimer′s Disease Neuroimaging Initiative), including significant memory concern (SMC), early mild cognitive Impairment (EMCI), late mild cognitive impairment (LMCI) and normal control (NC). The method had four different types of data for NC vs. SMC, SMC vs. EMCI, SMC vs. LMCI and EMCI vs. LMCI. The diagnostic result was 76.67%, 79.07%, 80.56% and 74.29%, respectively. Compared with other traditional algorithms, the classification accuracy of the methods described in this paper was significantly improved. The experimental results showed that the proposed method could be effectively applied to the diagnosis and analysis of early mild cognitive impairment.
		2019 Vol. 38 (6): 653-661 [Abstract] ( 387 ) HTML (1 KB) PDF (6896 KB) ( 325 )

	662	Fetal ECG Extraction from Single-Channel Abdominal ECG Based on EKF Combined with SVD
		Bu Zhaohui, Zhou Bin, Yin Xiaojing, Zheng Zheng
		DOI: 10.3969/j.issn.0258-8021.2019.06.003
		In this paper, an approach based on extended Kalman filtering (EKF) combined with singular value decomposition (SVD) was proposed to extract fetal electrocardiogram (fECG) from single-channel abdominal ECG recording. First, on the basis of the dynamic model of maternal electrocardiogram established, the maternal ECG component was estimated from the single-channel abdominal signal by EKF or extended Kalman smoothing (EKS). Next, the preliminary estimation of fetal ECG was obtained by subtracting the maternal ECG component from the single-channel abdominal signal. To obtain the fetal ECG with high signal-to-noise ratio, the preliminary fetal ECG was denoised using SVD. In addition, an improved construction method of the ECG signal reconstruction matrix was proposed in the SVD algorithm for the case of fetal arrhythmia. Synthetic abdominal signals and real abdominal signals (49 abdominal channels in total from DaISy database and PhysioNet non-invasive fetal ECG database) were used for fetal ECG extraction. The results showed that the signal-to-noise ratio of fetal ECG extracted by EKF+SVD or EKS+SVD was about 5 dB higher than that by EKF or EKS alone, and the accuracy of fetal ECG extraction was 95.60% and 95.94%, respectively. In conclusion, the single-channel fetal ECG extraction method based on the combination of EKF and SVD could effectively improve the signal-to-noise ratio and accuracy of fetal ECG signals extraction, and would be suitable for maternal or fetal arrhythmia.
		2019 Vol. 38 (6): 662-671 [Abstract] ( 438 ) HTML (1 KB) PDF (1828 KB) ( 238 )

	672	Characteristics of EEG Response Evoked by Postural Perturbation During Standing with Upper Limb Support
		He Feng, Zhang Jie, Jiang Shenglong, Qi Hongzhi, Xu Rui, Meng Lin, Ming Dong
		DOI: 10.3969/j.issn.0258-8021.2019.06.004
		This study investigated the characteristics of EEG response evoked by postural perturbation during standing with upper limb support, aiming to provide a new idea for detecting the instability of patients with lower extremity motor dysfunction. The experimental equipment was designed to apply rapid and sudden change of upper limb supporting force on random side of human body to simulate the perturbation during upper limb assisted standing. The EEG of 64 channels, two sides of supporting force andsurface electromyogram (sEMG) of smaller forearm extensors on both sides of 20 subjects were recorded synchronously. We analyzed the neural response characteristics of EEG evoked potential, and the behavioral response characteristics of mechanical signal and sEMG. Results: After the postural perturbation was applied, the supporting force on the perturbed side suddenly decreased in the time of (200.5±15.4) ms. Meanwhile, sEMG of smaller forearm extensors on both sides increased, and the sEMG of perturbed side was higher than the other side. Following postural perturbation onset, N1 potentials were observed with a peak latency of (62.3±5.5) ms and the peak activity was located at FCz electrode with a peak amplitude of (15.6±6.1) μV. The peak latency of P2 potentials were (167.4±12.4) ms and peak amplitude were (5.2±4.5) μV. The findings of this study provided a feasibility of detecting human unsteady state through neural response process.
		2019 Vol. 38 (6): 672-678 [Abstract] ( 434 ) HTML (1 KB) PDF (4178 KB) ( 252 )

	679	Research on the Influence of Music Type on Learning and Memory Based on EEG Signal Source Tracing Analysis
		Li Jipeng, Li Ying, Zhang Dongying, Feng Hao, Yin Ning
		DOI: 10.3969/j.issn.0258-8021.2019.06.005
		Music plays an important role in our daily life, and more and more scholars pay attention to the influence of music on learning cognitive activities. In this paper, 20 subjects in the EEG experiment for memorizing English words under three music conditions (non-music, classical music and rock music) was enrolled, and standardized low resolution brain electromagnetic tomography algorithm (sLORETA) was applied to reconstruct the sources, and statistical nonparametric mapping method (SnPM) was used to make pairwise comparison analysis of source localization results under three conditions. The localization analyses of EEG signals showed that ERP sources under different music types were mainly distributed in frontal lobes and temporal lobes. The localization results of P300 under non-music condition were mainly distributed in frontal lobe and left temporal lobes, and the localization results of P300 under classical music and rock music were mainly distributed in frontal lobe and right temporal lobe. Statistical analysis of the reconstruction results showed that there were significant differences between the ERP source current densities under different music types (P<0.05). The differences between non-music condition and classical music condition were mainly concentrated in temporal lobe. The differences between non-music condition and rock music condition were mainly concentrated in temporal lobe and frontal lobe. The differences between classical music condition and rock music condition were mainly concentrated in frontal lobe and occipital lobe. Statistical analysis of the behavioral data showed that the correct response rates of the subjects for memorizing words under non-music condition was about 91.00%±0.64%, that of classical music was about 86.00%±0.45%, and that of rock music was about 80.00%±0.24%. The results suggest that music may stimulate the brain, and it may waste the resources of the brain for the current cognitive processing and reduce the efficiency of learning and memory.
		2019 Vol. 38 (6): 679-686 [Abstract] ( 468 ) HTML (1 KB) PDF (7936 KB) ( 167 )

	687	Assessment Effects of Repetitive Transcranial Magnetic Stimulation in Patients with Disorders of Consciousness by EEG
		Bai Yang, Xia Xiaoyu, Wang Yong, He Jianghong, Li Xiaoli
		DOI: 10.3969/j.issn.0258-8021.2019.06.006
		Recently, repetitive transcranial magnetic stimulation (rTMS) has been demonstrated to improve consciousness in patients with disorders of consciousness. However, there is significant difference of brain responses to rTMS between patients in minimally conscious state (MCS) and vegetative state (VS). This study aims to investigate the different effects of rTMS on the patients with disorders of consciousness, by measuring the EEG activity and functional connectivity. Twenty-four patients with disorders of consciousness were enrolled in real and sham rTMS sessions. The EEG (62 channels) was recorded before and immediately after rTMS. Relative power, phase-locking value and functional network properties were evaluated to assess brain changes induced by rTMS. After rTMS modulation, a significant increase power of Gamma band and enhanced functional connectivity were found in patients in MCS. And the enhanced connectivity was mainly located within fronto-central and fronto-parietal regions. In addition, network features derived from the graph theoretical analysis showed decrease of average path length (1.32±0.31 vs 1.08±0.22), increase of clustering coefficient (0.95±0.15 vs 1.12±0.21) and small-world characteristic (0.76±0.24 vs 1.06±0.32) in patients in MCS. No significant alterations were observed in gamma band for patients in VS. Given the role of high gamma activity in human consciousness and cognition. These results provided potential methods and mechanisms of evaluation rTMS effects in conscious rehabilitation of patients with disorders of consciousness.
		2019 Vol. 38 (6): 687-694 [Abstract] ( 498 ) HTML (1 KB) PDF (1864 KB) ( 863 )

	695	Cerebral Cortex Functional Connection Analysis of Magnetic Stimulation at Neiguan Acupoint (PC6) Based on Complex Network
		Yin Ning, Dai Yangyang, Sheng Hui, Xu Guizhi
		DOI: 10.3969/j.issn.0258-8021.2019.06.007
		Combined with magnetic stimulation technique, electroencephalogram (EEG) and traditional acupoint theory, the coordinated regulation process of cerebral cortex functional network evoked by acupoint stimulation was studied in this work. The EEG signals in resting state and magnetic stimulation at Neiguan (PC6) acupoint of 14 healthy subjects were reconstructed to determine the brain network nodes, using the group independent component analysis and standard low-resolution brain electromagnetic tomography. The correlation coefficient between the alpha-band power spectrums was calculated by the short-time Fourier transform and the cross-correlation method. Based on t-test and false discovery rate correction (FDR) the brain network connection edges (P<0.05, FDR corrected) were constructed. The functional connections of cerebral cortex were analyzed. Results showed that the functional connections of nodes in brain areas related to movement decreased by 22.9%, the functional connections of nodes in brain areas associated with emotion and memory increased by 93.8%, the functional connections of nodes in the frontal lobe and temporal lobe increased by 21.2% during magnetic stimulation. The topological structure changes of the cerebral cortex functional network caused by magnetic stimulation at PC6 are consistent with the function of the acupoint. This study provides new clues for revealing the mechanism of acupoint regulation.
		2019 Vol. 38 (6): 695-701 [Abstract] ( 357 ) HTML (1 KB) PDF (2068 KB) ( 248 )

	702	Risk Prediction and Key Influence Factors Analysis ofAcute Kidney Injury in Inpatients
		Zhang Qin, Guo Shengwen, Liang Xinling, Chen Yuanhan, Wu Yanhua, Fu Lei
		DOI: 10.3969/j.issn.0258-8021.2019.06.008
		Acute kidney injury (AKI) is one of the most common critical diseases in inpatients, which has high morbidity and mortality. This study aimed to build model to predict AKI and analyze the risk factors affecting AKI occurrence, leading to timely intervene for patients with potential risk of AKI. A total of 90780 subjects (7983AKI and 82797 non-AKI, dividing training sets and independent test sets by 4:1) who stayed from 2 to 14 days were selected, and their biochemical indicators, drug use, demographic information and other clinical information were collected. Three models including logical regression, random forest and LightGBM were adopted to fulfill AKI prediction, and the performance of different models was evaluated and compared using sensitivity, specificity, the area under the characteristic working curve (AUC) and F1 value. LighGBM obtained the best performance to predict occurrence of AKI in 24 hours, the optimal F1, AUC, sensitivity, specificity was 0.800, 0.871, 0.755 and 0.987 respectively. The important factors affecting the occurrence of AKI include: Clinical features: age, the length of stay, admission department; Laboratory test: Creatinine value in the first examination, levels of sodium, potassium, chlorine, uric acid and glycosylated hemoglobin in blood; Medicine: Anti-infective drugs, non-steroidal anti-inflammatory drugs, diuretics or dehydrants, adrenergic receptor agonists, contrast agents, ACEI/ARB antihypertensive drugs as well as the types of drug used, days of drug treatment; Comorbidities: Moderate and severe nephropathy. Using the clinical information of inpatients, machine learning model can effectively predict the risk of AKI in 24 hours, reveal the important factors affecting the occurrence of AKI, and provide important basis for rational and effective treatment of inpatients and timely intervention for patients with AKI risk.
		2019 Vol. 38 (6): 702-710 [Abstract] ( 363 ) HTML (1 KB) PDF (1162 KB) ( 470 )

	711	Construction of Auricular Cartilage ModelsBased on Multimodal MRI Images
		Liu Xiaofang, Zhao Cheng
		DOI: 10.3969/j.issn.0258-8021.2019.06.009
		Constructing high-fidelity cartilage scaffolds has always been the research core of auricle reconstruction. Traditional imaging methods have a lower discrimination between auricular cartilage and surrounding tissues. In order to explore a new MRI scanning scheme for auricular cartilage imaging, and construct high-precision 3D bioprinting models of the auricular cartilage, this study proposed the combination of ultrashort time to echo (UTE) and 3D_T2 sequences. We collected unilateral external auricle images of 40 healthy volunteers. First, two experienced raters segmented auricular cartilages layer by layer based on UTE images, and remove other tissues such as earlobe according to the 3D_T2 images. Each rater repeated 3 times. Next, the inter- and intra-rater correlations between volume (Cg. V), surface area (Cg. S), and thickness (Cg. Th) of segmentation results were calculated to evaluate whether different raters could define the same area of interest. Results indicated that intra-rater precision errors(PE_CV)were Cg.V≤3.05%,Cg.S≤1.80%,Cg.Th≤3.43%, and the inter-rater PE_CV were Cg.V=2.39%,Cg.S=3.75%,Cg.Th=3.37%. The intra-class correlation coefficients (ICC) of Cg.V,Cg.S and Cg.Th were higher than 0.95, 0.97 and 0.77, the inter-class correlation coefficients were 0.97, 0.89 and 0.69, respectively. The Dice similarity coefficient (DSC) reached to above 80%. This study demonstrated that the combination of UTE and 3D_T2 was a scanning solution for auricle reconstruction research for its ability to characterize morphological differences in auricular cartilage and provide high precision auricular cartilage models for 3D bioprinting.
		2019 Vol. 38 (6): 711-718 [Abstract] ( 388 ) HTML (1 KB) PDF (4730 KB) ( 295 )

	719	Optimization of Cryoprotectants Addition and Removal Protocols Using Microfluidic Chip
		Zhou Xinli, Du Yukun, Yi Xingyue, Dai Jianjun, Zhang Defu
		DOI: 10.3969/j.issn.0258-8021.2019.06.010
		Cryoprotectants (CPA) addition and removal are essential steps in oocytes cryopreservation. In recent years, microfluidic chips have been used for addition and removal of CPA. The way of addition and removal in microfluidic chips will affect the survival rate and in vitro development of oocytes. In this paper, linear, convex and concave CPA loading or removal protocols were realized by adjusting injection models of microinjection pumps. Nine addition-removal combined protocols were achieved in the microfluidic system. The survival rate and in vitro development of oocytes with different CPA addition-removal protocols were investigated. Results showed that the survival rate (97.22%) and morula rate (46.03%) of porcine MII oocytes from concave loading-convex unloading protocol were significantly higher than that using other protocols(P < 0.05). There was a certain matching relationship between the addition and removal of CPA. This research provided a new solution for optimizing continuous addition-removal of CPA by microfluidic method.
		2019 Vol. 38 (6): 719-725 [Abstract] ( 331 ) HTML (1 KB) PDF (3176 KB) ( 174 )

	726	Study on 3D Bioprinted Liver Structure Implanted in the Fibrosis Liver of Rabbits
		Tang Liang, Luo Tao, Yang Yadong, Yang Geng, Xu Yimeng, Zhang Wenyuan
		DOI: 10.3969/j.issn.0258-8021.2019.06.011
		Three dimensional (3D) bioprinted liver-like hydrogel structures were implanted into the fibrosis liver of rabbit models by the liver surface cladding method to study its feasibility of improving the liver fibrosis and of generating liver-like tissue. Primary hepatocytes were extracted from the liver tissue of rabbit by 0.1% collagenase type IV digestion, and the hepatic fibrosis model was established by subcutaneous injection of carbon tetrachloride (CC1₄) into rabbits. Thirty rabbits with liver fibrosis were randomly divided into experimental group, control group, and sham operation group, with 10 rabbits in each group. The structure lamella containing rabbit primary hepatocytes/alginate/gelatin blend was constructed using 3D bioprinting technique. Then the 3D structure lamellas were implanted into the liver surface of hepatic fibrosis rabbits, as an experimental group. Sixteen days after implantation, liver functional biochemical index and liver histopathological changes of the liver were examined as well as the developmental degrees of hepatic fibrosis and the formation of liver-like tissue structure. The 3D structures with the grid hydrogel composing of multilayer staggered cylindrical microfilament were obtained and live/dead cell fluorescent staining results showed that the hepatocytes’ survival rate was about 82% ± 3% after printing. Most of the implants were not degraded 16 days after the implantation. The undegraded implants were tightly integrated into the liver. The biochemical indexes of liver function in the experimental group were ALT (90.26±13.05)U/L, AST (75.37±13.45)U/L, γGT (16.62±6.72)U/L, ALB (32.48±4.43)g/L. The significance between any two groups was P>0.05. The pathological examination scores of liver fibrosis degree in the experimental group, control group and sham operation group were 2.95±0.50, 3.11±0.58 and 3.02±0.62, respectively, and the significance between any two groups was P>0.05. The results showed that the fibrosis degree and the function of the rabbits’ liver had improvements to some extents in experimental group though there was no statistical significance. Histological observations from the experimental group showed that hepatocytes were evenly distributed, and that cell degeneration and death were not discovered, succeeding in generating liver-like tissue structure. In conclusion, the bioprinted hepatic structure has potentials of regenerating liver-like tissue structure and rebuilding liver functions.
		2019 Vol. 38 (6): 726-732 [Abstract] ( 340 ) HTML (1 KB) PDF (12114 KB) ( 118 )

	733	Study on the Mechanism of Tannic Acid Inducing Bovine Jugular Vein Cross-Linking
		Zheng Xiaobing, Zhou Jianye, Wang De, Dai Zehui, Guo Baohua
		DOI: 10.3969/j.issn.0258-8021.2019.06.012
		The aim of this study was to investigate chemical reactions of tannic acid (TA) with bovine jugular vein (BJV). Glutaraldehyde-fixed BJVs were subsequently treated with TA or four substitutional compounds, which contained four characteristic chemical groups of tannic acid. The treated BJVs were implanted subcutaneously into 20 SD rats for 21 and 60 days. The calcium content of the explanted tissues was assessed using atomic absorption spectrometry, and the degree of cross-linking was measured by Masson and EVG staining. In vitro, they were characterized with thermal stability, resistance to enzymatic hydrolysis, mechanical properties. The Fourier transform infrared spectroscopy (FTIS) was employed to inspect the changes of absorption curve. Furthermore, a gradient concentration of urea (0.1, 0.3, 0.5 and 1 M) was used to verify if hydrogen bond was formed. Tannic acid treated BJV, with polyphenolic hydroxyl groups in the compound, showed the best performance among the all BJVs. Which suggested effective cross-linking was formed in the tissue, and the calcium content at 21 d and 60 d was 2.25 mg/g and 8.26 mg/g respectively (P< 0.05). FTIS results indicated that hydrogen bond was formed in TA group and it was confirmed by urea test. The urea test showed that the effect of cross-linking between tissue decreased (P< 0.05) with the increase of urea concentration, and the calcium content of TA group was 8.10 mg/g at 60 d, which was much lower than 16.83 mg/g of the 0.1 M urea group and 50.76 mg/g of the 0.5 M urea group(P < 0.001). Our results demonstrated that the hydrogen bond was formed between polyphenolic hydroxyl groups and proteins in TA treated BJVs. It may provide a clue to improve the stability of the reaction system.
		2019 Vol. 38 (6): 733-741 [Abstract] ( 353 ) HTML (1 KB) PDF (19549 KB) ( 123 )

Rreviews

	742	Research Progress and Prospects of Motor Neurofeedback Rehabilitation Training after Stroke
		Wang Mengya, Wang Zhongpeng, Chen Long, Wan Baikun, Gu Xiaosong, Ming Dong
		DOI: 10.3969/j.issn.0258-8021.2019.06.013
		Stroke is a comprehensive disease of local dysfunction caused by sudden vascular disease in brain area, which is the first malignant neurological disease in the world. Exercise rehabilitation training plays an important role in the recovery of function after stroke. The key lies in the improvement of the plasticity of the injured nerve tissue in brain area through limb movement induction to achieve the improvement and recovery of motor function. However, traditional passive repeated training approaches cannot arouse patients’ participation and enthusiasm, which seriously affects the rehabilitation effect. In recent years, the model of motor neurofeedback rehabilitation training based on the motor imagery brain-machine interface (MI-BCI) can be driven by the endogenicity of patients′ subjective motor intention to produce plastic changes in the corresponding brain regions, and it can promote limb motor rehabilitation through brain functional recombination. This paper reviewed the application of different motor neurofeedback modes including proprioception and visual feedback in stroke rehabilitation training, discussed the existing challenges and solutions of the current MI-BCI neurofeedback rehabilitation training system, and provided opinions for the future development.
		2019 Vol. 38 (6): 742-752 [Abstract] ( 480 ) HTML (1 KB) PDF (7692 KB) ( 162 )

	753	Application of Tissue Engineered Materials in the Repair of Myocardial Injury
		Chen Simin, Xie Guoping, Gao Yanan, Zhan Haihe, Wu Linhua
		DOI: 10.3969/j.issn.0258-8021.2019.06.014
		Myocardial infarction is a serious disease that threat human health. In the field of cardiovascular disease treatment, the lack of self-repairing ability of myocardial tissue is one of the challenges. Current therapeutic treatments for myocardial infarction are not able to recover the normal functions. Cardiac tissue engineering may be an important potential approach to repair damaged myocardial tissue. Tissue engineered materials can be used to deliver stem cells (bone marrow mesenchymal stem cells, embryonic stem cells, etc.), drugs or growth factors, and simulate extracellular matrix. Main investigations in this field include the delivery of stem cells and growth factors by scaffolds to repair myocardium, and have made remarkable progress. This article reviewed the recent application of tissue engineered materials in the field of cardiac tissue engineering as essential delivery carriers.
		2019 Vol. 38 (6): 753-758 [Abstract] ( 436 ) HTML (1 KB) PDF (792 KB) ( 653 )

Communications

	759	The Recognition of Driver′s Fatigue Based on Dynamic Bayesian Estimation
		Fu Rongrong, Tian Yongsheng, Wang Shichao, Wang Lin
		DOI: 10.3969/j.issn.0258-8021.2019.06.015

		2019 Vol. 38 (6): 759-763 [Abstract] ( 451 ) HTML (1 KB) PDF (3660 KB) ( 270 )

	764	Transcranial Magnetic Stimulation Signal Denoising Based on Spectrum Domain Constraints Subspace Method
		Xiong Hui, Qi Hailong, Liu Jinzhen
		DOI: 10.3969/j.issn.0258-8021.2019.06.016

		2019 Vol. 38 (6): 764-768 [Abstract] ( 325 ) HTML (1 KB) PDF (1087 KB) ( 220 )

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