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find Keyword "弥散张量成像" 16 results
  • Experimental Study of Ventricular Myocardial Band Using Magnetic Resonance Diffusion Tensor Imaging Technique

    Objective To investigate the feasibility of magnetic resonance diffusion tensor imaging (MRDTI) technique in displaying myocardial fiber architecture. Methods In five ex vivo swine heart, diffusion tensor imaging (DTI) was acquired in 25 directions within 2 hours after excision. The myocardial fiber was reconstructed by using brain white matter tractography algorithm to display its course, distribution and arrangement. Results In the swine heart 1 hour after excision, MRDTI revealed that the arrangement of the myocardial fiber had certain continuity. It spiraled and twisted to form the left and right ventricle. The divection of general myocardial fiber in the left ventricle was vertical below endocardium, horizontal below epicardium and oblique in stratum medium, which is consistent with the theory of ventricular myocardial band. Conclusion MRDTI can reveal the myocardial fiber architecture, showing its integrity and arrangement, and at some level confirming the theory of ventricular myocardial band.

    Release date:2016-08-30 06:16 Export PDF Favorites Scan
  • 脑功能区胶质瘤手术策略的研究进展

    【摘要】 大脑功能区胶质瘤的手术治疗是神经外科临床工作非常棘手的问题。最大限度地切除病变、最大程度地保护功能区、避免术后神经功能缺失、提高患者术后生活质量,是脑功能区胶质瘤手术治疗的最高目标。术前功能神经影像、术中神经导航和超声、CT、MRI、肿瘤显色、电生理监测的应用,已成为当前脑功能区胶质瘤手术的重要策略。现就脑功能区手术策略的研究进行综述。

    Release date:2016-09-08 09:26 Export PDF Favorites Scan
  • 特发性全面性癫痫的神经影像研究进展

    特发性全面发作性癫痫(Idiopathic generalized epilepsy, IGE)是一类没有明显病因和大脑病灶的癫痫, 主要脑电图(EEG)表现为突出背景的双侧对称的癫痫放电。现在新兴的无创的神经成像技术改变了以前对IGE的脑结构和功能网络的研究模式。当前的研究者已经迅速地采用这些新技术研究IGE的脑特征性改变, 包括EEG、功能磁共振、同步脑电和功能磁共振、结构磁共振、弥散张量成像以及结构功能脑网络技术。这些发现表明IGE中皮层-丘脑网络中存在着结构和功能指标的异常, 且越来越多的多模态神经成像结果也评估了癫痫活动对大量脑功能网络的影响。将来的研究将集中在多学科的融合和发展多模态神经成像技术, 更深入地研究IGE的脑网络机制

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  • Early Abnormalities of Kidneys in Patients with Primary Hypertension by 3.0 T Functional Magnetic Resonance Imaging

    This study aims to detect early changes of kidney in patients with primary hypertension by 3.0 T functional magnetic resonance imaging (fMRI). 26 patients with primary hypertension (hypertension group) and 33 healthy volunteers (control group) underwent conventional and functional magnetic resonance scans, which included blood oxygen level-dependent (BOLD) MRI, diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI). We measured renal cortical thickness (CT), parenchymal thickness (PT), and functional values of renal cortex and medulla including R2* value, apparent diffusion coefficient (ADC) value and fractional anisotropy (FA) value in each group, and then calculated the cortical/parenchymal thickness ratio (CPR). Compared with those in the control group, CT and CPR in hypertension group were larger (P<0.01), cortical and medullar R2* values increased (P<0.01) whereas medullar FA values decreased (P<0.05). It could be well concluded that noninvasive 3.0 T functional MRI would have important clinical significance in identifying early abnormalities of kidney in hypertension patients.

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  • Study on Abnormal Topological Properties of Structural Brain Networks of Patients with Depression Comorbid with Anxiety

    This paper is aimed to analyze the topological properties of structural brain networks in depressive patients with and without anxiety and to explore the neuropath logical mechanisms of depression comorbid with anxiety. Diffusion tensor imaging and deterministic tractography were applied to map the white matter structural networks. We collected 20 depressive patients with anxiety (DPA), 18 depressive patients without anxiety (DP), and 28 normal controls (NC) as comparative groups. The global and nodal properties of the structural brain networks in the three groups were analyzed with graph theoretical methods.The result showed that ① the structural brain networks in three groups showed small-world properties and highly connected global hubs predominately from association cortices; ② DP group showed lower local efficiency and global efficiency compared to NC group, whereas DPA group showed higher local efficiency and global efficiency compared to NC group; ③ significant differences of network properties (clustering coefficient, characteristic path lengths, local efficiency, global efficiency) were found between DPA and DP groups; ④ DP group showed significant changes of nodal efficiency in the brain areas primarily in the temporal lobe and bilateral frontal gyrus, compared to DPA and NC groups. The analysis indicated that the DP and DPA groups showed nodal properties of the structural brain networks, compared to NC group. Moreover, the two diseased groups indicated an opposite trend in the network properties. The results of this study may provide a new imaging index for clinical diagnosis for depression comorbid with anxiety.

    Release date:2017-01-17 06:17 Export PDF Favorites Scan
  • STUDY ON RELATIONSHIP BETWEEN DIFFUSION TENSOR IMAGING AND VISUAL EVOKED POTENTIAL IN VISUAL PATHWAY OF NEUROMYELITIS OPTICA

    ObjectiveTo study the relationship between brain white matter fiber occult lesions and P100 wave latency of visual evoked potential (VEP) in neuromyelitis optica (NMO) patients by diffusion tensor imaging (DTI). MethodsTwenty patients with NMO who were treated between July 2008 and April 2009 were selected as the trial group. According to the VEP test, the latency of P100 wave was prolonged, the NMO patients were divided into VEP abnormal group (trial group 1) and VEP normal group (trial group 2). Twenty healthy adult volunteers served as the control group. The DTI examination in brain was done to measure the fractional anisotropy (FA) value of optic nerve (FAn), optic tract (FAt), and optic radiation (FAr);and the mean diffusivity (MD) value of optic nerve (MDn), optic tract (MDt), and optic radiation (MDr). The FA, MD, and P100 wave latency were compared between groups, and the correlation between MD, FA, and P100 wave latency of NMO were analyzed. ResultsIn the 20 NMO patients, 13 patients with VEP had prolonged bilateral P100 wave latency prolongation or no wave (trial group 1), and 7 patients had normal bilateral P100 wave latency (trial group 2). Compared with the trial group 2 and the control group, the FA values were significantly decreased, and the MD values were significantly increased in the trial group 1 (P<0.05). There was no significant difference in the FA and MD values between the trial group 2 and the control group (P>0.05). All FA (FAn, FAt, and FAr) values of each part of NMO patients were negatively correlated with the latency of P100 wave (P<0.05), all MD (MDn, MDt, and MDr) values were positively correlated with the latency of P100 wave (P<0.05). ConclusionDTI could show small pathylogical changes in the white matter fibers of visual pathway, and there is a correlation between DTI and VEP in NMO, suggesting that a more comprehensive assessment to the condition and prognosis can be made through the VEP in the clinical indicators.

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  • 特发性震颤的磁共振功能成像进展

    特发性震颤(essential tremor,ET)是临床最为常见的神经系统疾病之一,以姿势性或动作性震颤为主要临床表现。磁共振功能成像(functional magnetic resonance imaging,fMRI)是 20 世纪 90 年代以来在传统的 MRI 技术的基础上迅速发展起来的一种新的成像技术。该文就 fMRI 在 ET 中的应用原理、病理生理机制、鉴别诊断以及发展前景等方面进行了综述。

    Release date:2017-05-18 01:09 Export PDF Favorites Scan
  • Structural abnormalities of default mode network in childhood absence epilepsy revealed by diffusion tensor imaging

    ObjectiveChildhood absence epilepsy (CAE) is a common syndrome of idiopathic generalized epilepsy.However, little is known about the brain structural changes in this type of epilepsy, especially in the default mode network (DMN) regions.Diffusion tensor imaging (DTI) is a noninvasive techniques that can be used to quantitatively explore structural characteristics of brain.This study aims at using the DTI technique to quantify structural abnormalities of DMN nodes in CAE patients.MethodDTI data were obtained in 14 CAE patients and 13 age-and gender-matched healthy controls.The data were analyzed using voxel-based analysis (VBA) and statistically compared between patients and controls.For the regions with significant difference in group comparison, their DTI metrics were further analyzed with clinical symptoms using Pearson's correlation.ResultsPatients showed significant increase of apparent diffusion coefficient (ADC) in left medial prefrontal cortex (MPFC) (P=0.042), while fractional anisotropy (FA) value was significantly decreased in left precuneus (P=0.010).In correlation analysis, ADC value from left MPFC was positively associated with duration of epilepsy.Neither the disease duration nor the seizure frequency showed significant correlation with FA values.ConclusionThe findings indicate that structural impairments exist in DMN regions in children suffering from absence epilepsy.This may contribute to understanding the pathological mechanisms and chronic neurological deficits of this disorder.

    Release date:2017-05-24 05:46 Export PDF Favorites Scan
  • Tract-based spatial statistics analysis on the white matter of patients with temporal lobe epilepsy and automatic recognition

    This study aims to determine the salient brain regions with abnormal changes in white matter structures from diffusion tensor imaging (DTI) images of the patients with temporal lobe epilepsy (TLE), and to discriminate the patients with TLE from normal controls (NCs). Firstly, the DTI images from 50 subjects (28 NCs and 22 TLE) were acquired. Secondly, the four measures including the fractional anisotropy (FA), the mean diffusivity (MD), the axial diffusivity (AD) and the radial diffusivity (RD) were calculated. Thirdly, the tract-based spatial statistics (TBSS) was adopted to extract the measures in brain regions with significant differences between the two compared groups. Fourthly, the obtained measures were used as input features of the support vector machine (SVM) for classification, and the support vector machine-recursive feature elimination (SVM-RFE) was compared with the support vector machine-tract-based spatial statistics (SVM-TBSS) method. Finally, the essential brain regions and their spatial distribution were analyzed and discussed. The experimental results showed that the FA measures of the TLE group decreased significantly in the corpus callosum, superior longitudinal fasciculus, corona radiata, external capsule, internal capsule, inferior fronto-occipital fasciculus, fasciculus uncinatus and sagittal stratum, which were nearly bilaterally distributed, while the MD and RD increased significantly in most of these brain regions of the TLE group. Although the AD also increased, the differences were not statistically significant. The SVM-TBSS classifier obtained accuracies of 82%, 76% and 76% using the FA, MD and RD for classification, respectively, and 80% using combined measures. The SVM-RFE classifier obtained accuracies of 90%, 90% and 92% using the FA, MD and RD respectively, while the highest accuracy was 100% using combined measures. These results demonstrated that the SVM-RFE outperformed the SVM-TBSS, and the dominant characteristic influencing classification in brain regions were in associative and commissural fibers. These results illustrated that the measures of DTI images could reveal the abnormal changes in white matter structure of patients with TLE, providing effective information to clarify its pathological mechanism, localize the focus and diagnose automatically.

    Release date:2017-08-21 04:00 Export PDF Favorites Scan
  • Research on brain white matter network in cerebral palsy infant

    Present study used diffusion tensor image and tractography to construct brain white matter networks of 15 cerebral palsy infants and 30 healthy infants that matched for age and gender. After white matter network analysis, we found that both cerebral palsy and healthy infants had a small-world topology in white matter network, but cerebral palsy infants exhibited abnormal topological organization: increased shortest path length but decreased normalize clustering coefficient, global efficiency and local efficiency. Furthermore, we also found that white matter network hub regions were located in the left cuneus, precuneus, and left posterior cingulate gyrus. However, some abnormal nodes existed in the frontal, temporal, occipital and parietal lobes of cerebral palsy infants. These results indicated that the white matter networks for cerebral palsy infants were disrupted, which was consistent with previous studies about the abnormal brain white matter areas. This work could help us further study the pathogenesis of cerebral palsy infants.

    Release date:2017-10-23 02:15 Export PDF Favorites Scan
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