重症肌无力患者静息态脑功能磁共振成像与认知功能的研究

目的 运用静息态脑功能磁共振成像(rs-fMRI)技术探索重症肌无力患者(MG)脑功能局部一致性(Re-Ho)及认知功能的改变.方法 30例重症肌无力患者(MG组)和30例健康志愿者(对照组)分别进行rs-fMRI检查和临床量表评分.采用双样本t检验对两组受试者全脑的ReHo值及临床量表评分进行组间差异分析,MG患者异...     

脑高级功能的功能磁共振成像研究

大脑是生物体内结构和功能最复杂的组织 ,大脑的神经细胞总数约为 1 0 1 2 个 ,相当于整个银河系星体的总数。此外 ,它还有比神经细胞多 1 0～ 50倍的神经胶质细胞 ,这些神经胶质细胞也可能在处理信息中起作用。另外 ,大脑是人体接受外界信号、产生感觉、形成意识、进行逻辑思维、发出指令、产生行为的指挥部 ;是人体内外环境信息获得、存储、处理、加工和整合的中枢。对脑高级功能的研究有助于我们认识脑、保护脑、乃至创造脑[1 ] 。脑高级功能包括语言、记忆、感知觉、情绪、思维等许多方面。历史上最早是从解剖人的尸体和研究脑局部损伤…     

磁共振波谱与脑功能成像

随着磁共振波谱技术及功能性磁共振技术的日臻完善和发展,人们对脑,这个人体内最复杂和最重要的器官的认识,从单纯的影像学研究转而进入了分子水平和超细胞(行为)等各个不同层次上的深入探索。这些对于从本质上揭示脑的结构、功能及行为机制之间的关系无疑提供了巨大的研究前景。本文对磁共振波谱技术的原理及目前在临床和基础科学领域取得的进展作简单回顾,对其在脑功能研究中的地位和价值作出评价。一、磁共振波谱(ｍａｇｎｅｔｉｃｒｅｓｏｎａｎｃｅｓｐｅｃｔｒｏｓｃｏｐｙ,ＭＲＳ)是一种利用核磁共振现象和化学位移作用,进行系列特定…     

静息态磁共振成像技术对终末期肾病患者异常脑功能连接的研究进展

终末期肾病(ESRD)可由于多种复杂的因素对患者的大脑功能产生影响,其具体表现为脑功能网络连通性的普遍降低,以及部分功能网络之间连通活动的减弱。异常的脑功能连接是终末期肾病患者认知功能障碍产生的重要原因。静息态磁共振功能成像(rs-fMRI)可以通过监测局部血氧水平的改变来反映大脑的神经活动,从而间接反映脑网络功能的整合情况,它是探究肾病患者异常脑功能连接生理机制的重要手段。本文就脑功能连接的理论基础及静息态磁共振成像对ESRD患者脑功能连通性的应用进展进行综述。     

脑高级功能磁共振成像研究

大脑是生物体内结构和功能最复杂的组织，大脑的神经细胞总数约为1012个，相当于整个银河系星体的总数。此外，它还有比神经细胞多10-50倍的神经胶质细胞，这些神经胶质细胞也可能在处理信息中起作用。另外，大脑是人体接受外界信号、产生感觉、形成意识、进行逻辑思维、发出指令、产生行为的指挥部，是人体内外环境信息获得、存     

磁共振脑功能成像原理及应用

磁共振功能成像(FMRI)是一种新兴的影像学检查技术。以往的影像学检查技术绝大部分是依赖于被检组织形态学的改变，而功能性成像这一领域一直为正电子发射体层摄影(PET)所独有。随着MR技术的发展，FMRI能在特定的脑功能活动时或血液动力学变化时对脑组织进行实时的功能成像，对人脑在生理和病理状态下的功能活动进行有效的     

癫痫磁共振脑功能成像研究进展

癫痫是神经科仅次于脑血管病的第二高发疾病．其中约70％的病例可用药物治愈或控制．其余为难治性癫痫。手术治疗是控制顽固性癫痫的重要手段。目前,手术能使80％的患者癫痫发作得到有效控制,其治疗效果有赖于癫痫灶和脑功能区的准确定位。近年来磁共振功能成像(functional magnetic resonance imaging．fMRI)技术飞速发展,对癫痫患者认知功能及手术治疗评价能发挥重要作用。     

癫的静息态功能磁共振成像研究进展

癫日(EP)是临床常见危害性大的神经系统疾病之一,其治疗方案因病因不同而不同,影像学检查对病因诊断具有重要作用.但部分癫日病人依靠CT、常规MRI等常规影像学检查不能准确发现其致日灶.静息态功能磁共振成像(rs-fMRI)能从脑功能水平早期提示脑的病理生理变化,具有高空间分辨力、无创性、实用性的优势,对神经精神疾病的早期诊断、预后判断及疗效监测有较大临床价值,能检出常规MRI不能检测出的癫日灶.就rs-fMRI对癫日的定侧定位诊断、病理生理机制研究以及癫日的“默认网络”功能连接的研究进行综述.     

人类听觉的脑功能磁共振成像研究

脑功能磁共振成像(fMRI)已广泛应用于人体运动、感觉、视觉、味觉、语言及各种复杂认知任务的研究,近年来有关听觉的fMRI研究报道也日益增多,并显示出其潜在和广阔的临床应用前景.     

功能磁共振成像在脑膜瘤患者运动功能区的应用

目的：探讨血氧水平依赖功能磁共振技术(BOLD-fMRI)在脑膜瘤患者运动功能区术前定位的价值。方法收集10例经术后病理证实的靠近运动区的大脑凸面脑膜瘤患者,采用概率独立成分分析(PICA),进行 ICA 分析。术前术后行远期生活质量评估(KPS)生活状态评分来评价患者的状态。结果双侧主要运动皮层及辅助运动皮层均出现运动功能激活簇,其中患侧激活区与对侧激活区相比较为对称的有6例,出现明显推压移位的有4例,患者运动功能激活区均被肿瘤挤压导致功能区向前或向后移位,并且出现拉伸变形。结论 BOLD-fMRI 能够有效对脑肿瘤患者进行术前运动功能区定位,对脑膜瘤患者术前手术计划的制定能够提供帮助。     

Cortical mapping by functional magnetic resonance imaging in patients with brain tumors

The aim of our study was to establish the effectiveness of the functional MRI (fMRI) technique in comparison with intraoperative cortical stimulation (ICS) in planning cortex-saving neurosurgical interventions. The combination of sensory and motor stimulation during fMRI experiments was used to improve the exactness of central sulcus localization. The study subjects were 30 volunteers and 33 patients with brain tumors in the rolandic area. Detailed topographical relations of activated areas in fMRI and intraoperative techniques were compared. The agreement in the location defined by the two methods for motor centers was found to be 84%; for sensory centers it was 83%. When both kinds of activation are taken into account this agreement increases to 98%. A significant relation was found between fMRI and ICS for the agreement of the distance both for motor and sensory centers (p=0.0021–0.0024). Also a strong dependence was found between the agreement of the location and the agreement of the distance for both kinds of stimulation. The spatial correlation between fMRI and ICS methods for the sensorimotor cortex is very high. fMRI combining functional and structural information is very helpful for preoperative neurosurgical planning. The sensitivity of the fMRI technique in brain mapping increases when using both motor and sensory paradigms in the same patient.     

Quantitative magnetic resonance imaging of the fetal brain in utero: Methods and applications

Application of modern magnetic resonance imaging (MRI) techniques to the live fetus in utero is a relatively recent endeavor. The relative advantages and disadvantages of clinical MRI relative to the widely used and accepted ultrasonographic approach are the subject of a continuing debate; however the focus of this review is on the even younger field of quantitative MRI as applied to non-invasive studies of fetal brain development. The techniques covered under this header include structural MRI when followed by quantitative (e.g., volumetric) analysis, as well as quantitative analyses of diffusion weighted imaging, diffusion tensor imaging, magnetic resonance spectroscopy and functional MRI. The majority of the published work reviewed here reflects information gathered from normal fetuses scanned during the 3^rd trimester, with relatively smaller number of studies of pathological samples including common congenital pathologies such as ventriculomegaly and viral infection.     

Noise suppression digital filter for functional magnetic resonance imaging based on image reference data

The central decision in every functional magnetic resonance imaging (fMRI) experiment is whether pixels in brain tissues are showing activation in response to neural stimulus or as a result of noise. Images are degraded not only by random (e.g., thermal) noise, but also by structured noise due to MR system characteristics, cardiac and respiratory pulsations, and patient motion. A novel digital filter has been developed to suppress cardiac and respiratory structured noise in fMRI images, using estimates of structured and random noise power spectra obtained directly from the images. It is an adaptive filter based on stationary noise statistics, and is equivalent in form to a Wiener filter. A mathematical model of the filtering process was developed to understand how the strength and distribution of structured and random noise power influenced filter performance. The filter was tested using images from an auditory activation study in ten subjects. In subjects whose structured noise power was localized to a relatively narrow frequency range, a strong relationship was found, both experimentally (R = 0.975, P < 0.0004 for H_o: R = 0) and using the model, between filter performance and the level of structured noise power contaminating the experiment frequency. The filter significantly reduced the rate of false-positive activations in the subset of subjects whose experiment frequency was relatively heavily contaminated by structured noise. Notch filters, that simply eliminate unwanted frequencies, performed poorly in all subjects. Unlike the proposed Wiener filter, these filters did not suppress structured noise power at the experiment frequency that contributes to false-positive activations.     

Acoustic noise and functional magnetic resonance imaging: current strategies and future prospects

Functional magnetic resonance imaging (fMRI) has become the method of choice for studying the neural correlates of cognitive tasks. Nevertheless, the scanner produces acoustic noise during the image acquisition process, which is a problem in the study of auditory pathway and language generally. The scanner acoustic noise not only produces activation in brain regions involved in auditory processing, but also interferes with the stimulus presentation. Several strategies can be used to address this problem, including modifications of hardware and software. Although reduction of the source of the acoustic noise would be ideal, substantial hardware modifications to the current base of installed MRI systems would be required. Therefore, the most common strategy employed to minimize the problem involves software modifications. In this work we consider three main types of acquisitions: compressed, partially silent, and silent. For each implementation, paradigms using block and event-related designs are assessed. We also provide new data, using a silent event-related (SER) design, which demonstrate higher blood oxygen level-dependent (BOLD) response to a simple auditory cue when compared to a conventional image acquisition.     

Abnormal default-mode network activation in cirrhotic patients: a functional magnetic resonance imaging study

Background: Recently, increasing numbers of studies have demonstrated that, in humans, a default-mode functional network exists in the resting state. Abnormal default-mode network in various diseases has been reported; however, no report concerning hepatic cirrhosis has been published to date.

Purpose: To prospectively explore whether the resting-state network in patients with hepatic cirrhosis is abnormal or not, using functional magnetic resonance imaging (fMRI).

Material and Methods: 14 patients with hepatic cirrhosis (12 male, two female; 45±9 years) and 14 age- and gender-matched healthy volunteers (12 male, two female; 42±10 years) participated in a blocked-design fMRI study. A modified Stroop task with Chinese characters was used as the target stimulus. Statistical Parametric Mapping 99 software was employed to process the functional data. Individual maps and group data were generated for patients with hepatic cirrhosis and for healthy controls, respectively. Intergroup analysis between patients and healthy controls was also generated using the two-sample t-test model. Cluster analyses were done based on the group data, and an identical P value ≤0.01 with continuously connected voxels of no less than 10 was defined as significant deactivation. After fMRI scanning was complete, behavioral Stroop interference tests were performed on all subjects; reaction time and error number were recorded.

Results: Functionally, deactivation of the posterior cingulate cortex (PCC) and precuneus was absent when subjects performed the incongruous word-reading task; deactivation of the PCC, precuneus, and ventral medial prefrontal cortex was increased when they performed the incongruous color-naming task.

Conclusion: The functional as well as behavioral data suggest that cirrhotic patients may have an abnormal deactivation mode. The absence of deactivation in the PCC and precuneus may be a sensitive rather than specific marker in patients with hepatic cirrhosis.     

帕金森病非运动症状的MRI研究进展

帕金森病(PD)早期可以出现非运动症状,而且有可能是最先出现的症状。与其运动症状一样,同样会促使病情进展,造成或加重病人的残疾。多模态MRI可以发现PD伴认知功能障碍病人、PD伴抑郁病人在脑结构、代谢及功能方面的改变,对PD非运动症状的诊断、疗效监测和预后评估具有重要的作用。     

Spatially filtering functional magnetic resonance imaging data

When constructing MR images from acquired spatial frequency data, it can be beneficial to apply a low-pass filter to remove high frequency noise from the resulting images. This amounts to attenuating high spatial frequency fluctuations that can affect detected MR signal. A study is presented of spatially filtering MR data and possible ramifications on detecting regionally specific activation signal. It is shown that absolute activation levels are strongly dependent on the parameters of the filter used in image construction and that significance of an activation signal can be enhanced through appropriate filter selection. A comparison is made between spatially filtering MR image data and applying a Gaussian convolution kernel to statistical parametric maps.     

Nuclear magnetic resonance imaging (NMR), (MRI), of brain stem tumours

Summary The NMR scans of twenty-six patients who were referred with the clinically suspected or histologically verified diagnoses of brain stem tumour were reviewed. Twenty-one patients (eleven children and ten adults) had scans that were positive for tumour. Nine of these had histological confirmation. Eleven were irradiated without histology on the basis of the clinical diagnosis. The remaining patient was treated expectantly. The other five patients (two children and three adults) had CT and NMR scans that were negative for tumours. Clinical follow-up of these five cases for 9 to 29 months disclosed no further evidence of tumour. All but one tumour had evidence of an increased T₁ and T₂. Mass effects were seen in all but one case (not the same as the first exception). Multiplanar imaging was useful in determining intra- or extra-axial location as well as tumour extent. Intravenous Gadolinium-DTPA (a paramagnetic contrast agent) showed tumour enhancement in the two patients in whom it was used. NMR showed more extensive abnormality than CT in nineteen patients and similar abnormality to CT in two patients. CT demonstrated calcification better than NMR in the three cases in which it was observed.