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中国生物医学工程学会
北京玛格泰克科技发展有限公司
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2018 Vol. 27, No. 3
Published: 2018-09-01
Research papers
Research papers
93
An Approach for Detecting Cerebral Artery Stenosis Based on MRA Images
LI Xing-wen, ZHOU Gang, YANG Ting, ZHANG Qi, QIAO Hui-ting, LI Shu-yu, LI De-yu
Cerebral artery stenosis is an important cause and risk factor to ischemic cerebrovascular disease. This paper describes a simple and effective method for the detection of cerebral artery stenosis in magnetic resonance angiography (MRA). Because of the complex structure of the brain blood vessels, the fast and accurate segmentation method is needed. Here, we used the information of the maximum intensity projection (MIP) image to get 3D vascular structure. As skeleton was one of useful measures for charactering region-based shape features, we extracted 3D-skeleton of blood vessels by using fast marching method (FMM). Finally, the accurate cross-sectional areas based on cerebrovascular skeleton were computed to determine the location and extent of vascular stenosis. The results showed that our method could effectively detect the cerebral artery stenosis.
2018 Vol. 27 (3): 93-99 [
Abstract
] (
28
)
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(1 KB)
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(3053 KB) (
116
)
100
Research on the Method of EEMD in Pulse Wave Signals Processing
XU Pan-pan, CHEN Chang-jun, LOU Hai-fang
The mixed noise in the acquisition process of pulse wave signals will affect the signal analysis, how to effectively eliminate the noise and complete the pulse wave analysis has important practical significance. In this paper, empirical mode decomposition (EMD) and ensemble empirical mode decomposition (EEMD) were used to realize scale decomposition of pulse wave signals to obtain intrinsic mode function (IMF). A band-pass filter was implemented according to the characteristic time scale parameters of the IMF. After filtering and reconstruction, the pulse wave denoising was completed. The denoising effects of EMD, EEMD and wavelet transform were compared in terms of mean square error and signal-to-noise ratio. The result shows that EMD and EEMD are better than wavelet transform, and the effects are similar. Further comparing the Hilbert-Huang spectrum of EMD and EEMD, it can be seen that EEMD can not only avoid mode mixing, but also facilitate the analysis of pulse wave signals.
2018 Vol. 27 (3): 100-108 [
Abstract
] (
29
)
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(3659 KB) (
143
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109
Functional and Structural Alterations in Temporal Lobe Tumor Patients: Evidence of Functional Compensation in the Human Brain
XUE Li, YANG Yu-xuan, LING Tao, YANG Ya-min, QIAN Zhi-yu
Patients with temporal lobe tumor are frequently accompanied by cognitive impairments. This study aims to combine diffusion tensor imaging (DTI) with resting-state functional magnetic resonance image (fMRI) to explore the underlying cognitive alternation and functional reorganization in patients with temporal lobe tumor. Twenty patients with right temporal lobe tumor and seventeen healthy volunteers were recruited in this study. Independent component analysis (ICA) was utilized to divide the whole brain into six sub functional networks, and DTI combined with graph-based topological analysis was used to calculate the structural properties of whole-brain and sub functional networks. Besides, the rich hubs in both patients and healthy controls (HCs) were identified and a further analysis of their internal functional and structural connectivity was also conducted. The
E
global
in self-referential network (SRN) of patients is higher than HCs, while decreased
E
global
of dorsal attention network (DAN) and default mode network (DMN) were found in patients. For the patients, brain regions with increased nodal efficiency(
E
nodal
) were located in the frontal lobe (corresponding to SRN). Six identical hubs were found in two groups. Compared patients with HCs, significant between-group differences in both functional and structural connectivity were observed between right insula (INS.R) and right lenticular nucleus, putamen (PUT.R). The findings provide evidence that impaired cognition are closely related to functional and structural abnormalities and the compensatory roles of frontal lobe were also identified in patients. The proposed combination of DTI and fMRI promises a widespread utilization in clinical research on the mechanisms of neurological diseases.
2018 Vol. 27 (3): 109-125 [
Abstract
] (
21
)
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(7832 KB) (
8
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126
Effects of Tensile Stimulation and Electrical Stimulation on the Connexion-43 mRNA Levels of Cardiomyocytes
in vitro
LI Ping, LI Yu, LIU Li-zhen, JIA Lu, SONG Yan-hui, JIA Xiao-ling, FAN Yu-bo
The heart is regulated by excitation-contraction mechanism and electrical stimulation, so both cardiac tissues and myocytes
in vivo
are affected by the mechanical and electrical factors at the same time. The device that can supply both tensile stimulation and electrical stimulation was produced. Cardiomyocytes were isolated by trypsin and collagenase II combined digestion. After 72 h's culture, different electrical stimulations (0.5 V/cm, 1 V/cm, 2 V/cm; 1 Hz; 2 ms; 30 min) and mechanical stretching force (tensile 10%, 6 h) were used to stimulate cultured cardiomyocytes respectively. Then the combinative stimulation of mechanical and electrical stimulation with 0.5 V/cm was used to apply to cardiomyocytes simultaneously. After stimulation, Connexin-43(Cx-43) mRNA level was detected by RT-PCR. The stimulation by electrical pulse of 0.5 V/cm resulted in obvious enhancement of Cx-43 mRNA level compared to the control group and the Cx-43 mRNA levels at 0.5 V/cm were higher significantly than those under both 1.0 V/cm and 2.0 V/cm. After 10% of tensile stimulation for 6 h, expressions of Cx-43 mRNA were also significantly promoted. The combinative effect of mechanical and electrical stimulation on the expression of Cx-43 mRNA is higher than that under unique tensile stimulation or electrical stimulation, which is more beneficial to the development and connection of cardiomyocytes.
2018 Vol. 27 (3): 126-134 [
Abstract
] (
19
)
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(1 KB)
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(3128 KB) (
109
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132
A Follow-up MRI-based Geometry and Computational Fluid Dynamics Study of Carotid Bifurcation
ZENG Yi-qiang, LI Zhi-yong
Cardiovascular disease is the leading causes of death in the developed world. Wall shear stress (WSS) is associated with the initiation and progression of atherogenesis. This study combined the recent advances in MR imaging and computational fluid dynanucs (CFD) and evaluated the patient-specific carotid bifurcation. The patient was followed up for 3 years. The geometry changes (tortuosity, curvature, ICA/CCA area ratios, central to the cross-sectional curvature, maximum stenosis) and the CFD factors (velocity distribute, wall shear stress (WSS) and oscillatory shear index (OSI) were compared at different time points.The carotid stenosis was a slight increase in the central to the cross-sectional curvature, and it was minor and variable curvature changes for carotid centerline. The OSI distribution presents a high-values in the same region where carotid stenosis and normal border, indicating complex flow and recirculation.The significant geometric changes observed during the follow-up may also cause significant changes in bifurcation hemodynamics.
2018 Vol. 27 (3): 132-138 [
Abstract
] (
40
)
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(1 KB)
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(2964 KB) (
104
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