颈部动脉夹层磁共振成像多序列评估与信号解读

动脉夹层是指由于动脉内膜损伤使血液通过内膜进入血管壁内而导致的动脉管壁分层,当动脉夹层内的血液导致病变动脉管壁呈瘤样膨出时称为夹层动脉瘤.动脉夹层是导致青年卒中的一个常见原因,尽早明确动脉夹层的诊断是指导下一步治疗的关键[1].虽然DSA是诊断动脉夹层的"金标准"[2],但近年来HR-MRI作为无创的成像解决方案也成为...     

TIA磁共振弥散加权成像异常的相关因素分析

目的探讨短暂性脑缺血发作(TIA)磁共振弥散加权成像(DWI)异常的相关因素。方法对2006年1月～2006年12月临床诊断为TIA的住院患者45例进行回顾性分析,比较DWI异常组和正常组的临床特征,并采用Logistic回归分析判定与DWI异常有关的独立因素。结果DWI异常14例(31%);多元回归分析提示TIA症状持续时间≥1h(OR=2.5,95%CI:1.3～8.6)和症状表现为失语伴运动障碍(OR=8.9,95%CI:2.1～36.5)与DWI异常独立相关。结论TIA患者DWI异常与TIA症状持续时间和症状表现为失语伴运动障碍有关。     

非感染性异常脑膜强化的磁共振成像诊断

磁共振成像(MRI)自应用于临床以来,使脑膜疾病诊断的敏感性大大提高,已成为诊断脑膜疾病的主要影像学检查手段.脑膜强化最常见于感染性脑膜炎,临床上采取影像学检查结合脑脊液检查较易确诊.然而,多种非感染性中枢神经系统病变也可以致脑膜异常强化,同时脑脊液检查又缺乏特异性,使诊断较为困难[1-4].我们回顾性分析了23例非感染性异常脑膜强化患者的MRI表现,以协助其病因诊断.     

脑血管畸形的磁共振成像和磁共振血管成像

目的：分析脑血管畸形在人振成像和磁共振共振血管成像的表面,并评估ＭＲＩ和ＭＲＡ在ＥＶＭ诊断方面的应用价值。方法：１８例经ＭＲＩ诊断为ＥＶＭ的患者,其中脑动静脉畸形１５例,隐匿性血管畸形３例。用Ｓｉｅｍｅｎｓ Ｖｉｓｉｏｎ ０．５Ｔ超导磁共和ＭＲＡ检查,采用ＴＯＦ－ｔｉ３ｄ－ｍｕｌｔｉ－ｔｒａ－ｔｕｎ序列。     

中枢神经系统磁共振成像

变性性脑疾病和脑铁沉着 作者:BurtonP.D 高磁场(如1.5T)磁共振成像(MRI)是活体构画脑铁的正常和病理分布的敏感方法,并能显示良好的解剖特征。在成人中,用多层次SE序列,T_2加权(TR=2500msec和TE=80msec)成像,显示苍白球、红核、网状黑质以及小脑齿状核显著的信号强度减低(T_2缩短)。在     

颈部脊髓静息态血氧水平依赖性功能性磁共振成像信号的频域分析

观察人体静息状态下,不同强度的颈部脊髓血氧水平依赖性功能性磁共振成像信号的频域分布特征。     

正常人脑白质磁共振成像高信号的危险因素和临床意义

检查１５８名正常人的脑磁共振成像（ＭＲＩ），发现４９名在Ｔ２加权像（Ｔ２ＷＩ）上显示白质高信号（ＷＭＨｓ）。分析ＷＭＨｓ与年龄、脑卒中危险因素及眼底动脉硬化间的关系发现，ＷＭＨｓ与年龄有显著相关性（Ｐ＜０．０５）；与脑卒中危险因素有非常显著相关性（Ｐ＜０．０１），且多个危险因素同时存在时其作用有叠加效应；与眼底动脉硬化间亦有显著相关性（Ｐ＜０．０５）。提示ＷＭＨｓ具有与脑卒中相同的危险因素，其出现可能导致老年人的认知功能减退、步态异常及平衡障碍。     

脑膜癌病的磁共振成像征象分析

目的探讨脑膜癌病的MRI表现,提高对脑膜癌病的影像学认识和诊断水平。方法对67例确诊的脑膜癌病患者的MRI平扫及增强影像学资料进行回顾性分析,总结其影像学特点。结果MRI平扫脑膜均未见异常信号,间接征象包括脑转移瘤11例,脑室扩大、脑积水8例;33例行增强检查后,18例(54.5%)有不同程度的脑膜强化。按脑膜强化的部位,10例显示软脑膜型异常强化,5例表现为硬脑膜型强化,3例为全脑膜型强化。按脑膜强化形状,线形强化9例,结节型5例,混合型4例。脑膜强化组与非脑膜强化组脑脊液比较,强化组的脑脊液蛋白和白细胞计数显著高于非强化组,而糖含量明显低于非强化组(P0.05)。结论增强MRI在显示本组脑膜癌病患者软脑膜-蛛网膜强化方面较为敏感,脑膜结节型或混合型强化是其较具特征的MRI表现,对脑膜癌病有重要的临床诊断价值。     

急性脑梗死患者临床表现与磁共振扩散加权成像和磁共振血管成像的相关性分析

目的：分析急性脑梗死患者的临床表现与磁共振扩散加权成像（DWI）和磁共振血管成像（M RA ）的相关性。方法回顾性分析51例急性脑梗死患者行DWI和M RA检查的临床资料,分析影像学特征。结果 DWI检查显示51例急性脑梗死患者均为高信号,而M RA检查显示阳性患者38例。结论对于急性脑梗死患者,DWI能够早期定位病灶及其性质, M RA能够显示颅内大血管狭窄或闭塞位置与程度,动态检测溶栓治疗效果,二者结合在指导临床和判定预后方面具有重要的作用。     

Problems in texture analysis with magnetic resonance imaging

Since its introduction in the 1930s, magnetic resonance imaging (MRI) has become recognized as a powerful in vivo diagnostic tool. The objective of this article is to discuss developments in quantitative MRI - and particularly texture analysis - that maximize diagnostic information, A fundamental part of the work involves careful study of the optimal MRI data collection strategies for texture analysis. This is critical, because different centers may vary their measuring sequences and acquisition protocols for clinical reasons, and may be reluctant to vary these for texture investigation. Different measuring techniques, such as spin echo, gradient echo, and echo planar, and different measuring parameters produce totally different patterns in texture. Careful investigation of the dependence of all these variables using texture phantoms (test objects) will help understand how MRI image texture is formed from tissue structures. Therefore, it is essential to design and test reliable and accurate test objects for a detailed assessment of texture analysis methods in MRI, The main feature of these test objects is their ability to simulate tissue-like textures with tissue-like MR relaxation properties. Long-term stability is also vital, as is uniformity of the overall texture. Another aspect is to examine the test objects under a whole range of MRI measuring sequences and imaging conditions using different scanners to determine their stability and utility.     

Texture analysis methodologies for magnetic resonance imaging

Methods for the analysis of digital-image texture are reviewed. The functions of MaZda, a computer program for quantitative texture analysis developed within the framework of the European COST (Cooperation in the Field of Scientific and Technical Research) B11 program, are introduced. Examples of texture analysis in magnetic resonance images are discussed.     

Voxelwise multivariate analysis of multimodality magnetic resonance imaging

Most brain magnetic resonance imaging (MRI) studies concentrate on a single MRI contrast or modality, frequently structural MRI. By performing an integrated analysis of several modalities, such as structural, perfusion‐weighted, and diffusion‐weighted MRI, new insights may be attained to better understand the underlying processes of brain diseases. We compare two voxelwise approaches: (1) fitting multiple univariate models, one for each outcome and then adjusting for multiple comparisons among the outcomes and (2) fitting a multivariate model. In both cases, adjustment for multiple comparisons is performed over all voxels jointly to account for the search over the brain. The multivariate model is able to account for the multiple comparisons over outcomes without assuming independence because the covariance structure between modalities is estimated. Simulations show that the multivariate approach is more powerful when the outcomes are correlated and, even when the outcomes are independent, the multivariate approach is just as powerful or more powerful when at least two outcomes are dependent on predictors in the model. However, multiple univariate regressions with Bonferroni correction remain a desirable alternative in some circumstances. To illustrate the power of each approach, we analyze a case control study of Alzheimer's disease, in which data from three MRI modalities are available. Hum Brain Mapp 35:831–846, 2014. © 2013 Wiley Periodicals, Inc.     

Functional magnetic resonance imaging of the normal and abnormal visual system in early life

Functional magnetic resonance imaging (fMRI) in young children may provide information about the development of the visual cortex, and may have predictive value for later visual performance. The purpose of this study was to evaluate the usefulness of fMRI for examining cerebral processing of vision in very young infants and in infants with brain damage. We examined 15 preterm infants, 12 children suspected of having a cerebral visual impairment and 10 children with a normal visual system, all of whom were either spontaneously asleep or sedated with chloral hydrate. Cortical response to stroboscopic light stimulation could be demonstrated in all technically acceptable data sets from children with a post-menstrual age (PMA) of > 41 weeks, but not in younger infants. Children < 60 weeks PMA showed either a blood oxygenation level-dependent (BOLD) signal increase or decrease, while all older children showed a signal decrease. The activated cortical volumes showed a linear relation to age for healthy children younger than 90 weeks PMA, but were small in children with visual impairment. In two children with unilateral damage to the optic radiations, activation was strongly asymmetrical with greatest activation on the healthy side. In future prospective studies, results from the period from birth to six months of age should be interpreted with caution, as inter-individual variation of cortical development may be confused with functional deficit.     

Functional magnetic resonance imaging evidence for task-specific activation of developmentally abnormal visual association cortex

Functional magnetic resonance imaging was performed on a 36-year-old woman with muscular dystrophy, intractable epilepsy, and bilateral temporo-occipital lissencephaly. We observed islands of task-specific activation in lissencephalic cortex homologous to visual association regions activated in normal subjects on the same visual confrontation naming task. This result suggests lissencephalic cortex may develop specific functional connections with other brain regions.     

Functional magnetic resonance imaging

Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) is a powerful approach to defining activity in the healthy and diseased human brain. BOLD fMRI detects local increases in relative blood oxygenation that are most probably a direct consequence of neurotransmitter action and thus reflect local neuronal signalling. The method allows localisation to volumes of the order of a few to several cubic millimetres and can be used in serial studies of individual subjects. Basic approaches to experimental design and analysis are reviewed briefly, as well as potential clinical applications. The latter include three broad areas: anatomical characterisation of normal or pathological patterns of brain functioning; distinguishing pathological traits; and monitoring treatment responses. New research is emphasising the integration of fMRI with other techniques, particularly electrophysiological. In conjunction with MRI methods for characterising pathological load, fMRI promises a refined understanding of when disease processes begin and how they can be modified by new treatments.     

Cerebellitis in an adult with abnormal magnetic resonance imaging findings prior to the onset of ataxia

BACKGROUND: Brain magnetic resonance imaging (MRI) findings during acute cerebellar ataxia in cases of postinfectious cerebellitis are frequently normal. This has resulted in the use of other imaging modalities, such as single-photon emission computed tomography, to aid diagnosis. OBJECTIVE: To illustrate the chronologic occurrence of cerebellar ataxia, abnormal findings on MRI, and cerebral spinal fluid pleocytosis in an adult case of postinfectious cerebellitis. METHODS: Case report. RESULTS: A patient with a 6-week history of occipital headaches and only mild tandem gait difficulty had abnormal MRI findings that were consistent with cerebellar inflammation. As cerebellar ataxia progressed in parallel with cerebral spinal fluid pleocytosis, MRI findings indicative of cerebellar inflammation resolved, while single-photon emission computed tomography showed cerebellar hyperperfusion. Recovery of neurologic function was accompanied by clearing of the pleocytosis and residual MRI-detected cerebellar atrophy. CONCLUSION: This case demonstrates that transient abnormalities can be detected by MRI before clinical manifestations of cerebellitis appear, while hyperperfusion detected by single-photon emission computed tomography is prolonged.