弥散张量成像对颅脑肿瘤与相邻脑白质纤维束解剖关系的评价

目的:评价弥散张量成像技术显示颅脑肿瘤与相邻脑白质纤维束解剖关系的价值。材料和方法:对5例正常志愿者及29例幕上星形细胞瘤及脑膜瘤进行弥散张量成像,在弥散各向异性图、彩色张量图及脑白质纤维束图上分析肿瘤与相邻脑白质纤维束的解剖关系,并对患者术前、术后的临床症状进行评价。结果:(1)9例脑膜瘤及11例Ⅰ-Ⅱ级星形细胞瘤推移相邻脑白质纤维束,患者术后临床症状明显改善。(2)6例Ⅲ-Ⅳ级星形细胞瘤及3例Ⅰ-Ⅱ级星形细胞瘤浸润、破坏相邻脑白质纤维束,患者术后的临床症状未明显改善。结论:弥散张量成像技术在显示颅脑肿瘤与相邻脑内主要白质纤维束的解剖关系方面具有重要价值,对神经外科术前治疗方案的确定具有重要指导作用。     

大脑胶质瘤DTT初步研究

目的:评价磁共振弥散张量纤维束成像技术在大脑胶质瘤所导致的大脑白质纤维异常改变中的价值。方法:分别对15例大脑胶质瘤患者进行弥散张量成像,对所获得的数据进行弥散张量纤维束成像,获得FA图、DEC图和DTT图,观察不同病变所引起的白质纤维束的改变情况。结果:15个病变累及的白质纤维束有弓状纤维、上纵束、内囊、上额枕束和胼胝体。白质纤维束的异常改变有2个类型:破坏 浸润5例、破坏 移位10例。结论:弥散张量纤维束成像可以显示颅内肿瘤所造成的白质纤维的异常改变,立体显示肿瘤与白质纤维束之间的关系,有利于肿瘤手术方案的制定和病人预后的预测。     

MRI DTI联合血氧水平依赖功能成像在星形细胞瘤术前的研究

目的探讨3.0T磁共振弥散张量成像(DTI)技术联合功能磁共振成像(fMRI)在星形细胞瘤与邻近脑白质纤维束解剖关系术前计划中的作用。方法对22例星形细胞瘤患者术前行常规MRI平扫,增强扫描及DTI技术fMRI检查,原始数据采集后进行图像分析处理,分别获得各项异性图(FA图),彩色编码张量图及脑白质纤维束图,并测定肿瘤的病灶区表观弥散系数(ADC值)及灶周水肿区各项异性分数(FA值)。分析肿瘤与相邻脑白质解剖关系,并对患者手术前后的临床症状进行评价。结果不同级别星形细胞瘤的肿瘤病灶区和灶周水肿区与正常白质区的ADC值和FA值存在差异,有统计学意义(P0.05﹚。白质纤维束可见受压、移位、浸润及破坏三种改变。4例Ⅰ~Ⅱ级星形细胞瘤推移相邻脑白质纤维束;8例Ⅱ~Ⅲ级星形细胞瘤侵润脑白质;10例Ⅲ~Ⅳ级星形细胞瘤破坏相邻脑白质纤维束。DTI图可以清晰显示运动区锥体束形态变化及与肿瘤之间的关系,在此基础上指导手术,效果满意。结论磁共振DTI技术联合fMRI是目前唯一在活体无创、三维清晰星形细胞瘤与周围白质纤维束的关系,由于二者的联合应用不仅能够显示大脑重要功能激活区在病理情况下的移位和改变,同时还能显示肿瘤与重要功能区和白质纤维束结构的关系,具有重要意义。     

正常成人大脑胼胝体弥散张量纤维束成像研究

目的 :利用磁共振弥散张量纤维束成像技术 ,研究正常成人大脑胼胝体的形状和结构。方法 :分别对 1 0名正常志愿者 (男 5例 ,女 5例。年龄为 2 4～ 6 5岁 ,平均年龄 4 0 .9岁 )进行弥散张量成像 ,将所得数据输入个人计算机 ,应用日本东京大学附属医院放射科影像计算和分析实验室所研制的软件 :Volume one1 .5 6和diffusionTENSORVisualizer 1 .5 (dTV)进行大脑胼胝体纤维束成像。结果 :本研究成功的在活体显示大脑胼胝体的形状和结构 ,在彩色FA图矢状面上胼胝体呈半月形 ,在弥散张量纤维束图横断面上呈蜈蚣状。结论 :弥散张量纤维束成像可以显示正常人大脑胼胝体 ,为大脑白质纤维束的研究开辟了一新的广阔领域。     

不同弥散梯度编码方向对胼胝体弥散张量成像的影响分析

目的 探讨胼胝体1.5T 磁共振弥散张量成像(DTI)较合理的弥散梯度编码方向.方法 连续采集30例健康成人志愿者,男女分别为16例、14例.分别施加15、25、39个弥散梯度磁场方向,行DTI扫描,3个不同弥散梯度磁场方向扫描时间分别为108 s、168 s、252 s.观察不同弥散梯度方向DTI的图像质量,在FA图上分别测量胼胝体膝部及压部的FA值,对测量值进行统计学分析.结果 所有FA图像均可清楚显示大脑白质纤维束,纤维束边缘显示清楚且能分辨出不同纤维束的解剖结构细节,与灰质形成鲜明对比.自15个弥散梯度磁场方向至25个、39个弥散梯度磁场方向,随着梯度磁场方向数量的增加,所得FA图示各部位白质纤维束边缘更加清楚、锐利,白质纤维束细节显示更加清晰.计算机重建的白质纤维束成像图(DTT图)也更加清晰丰富.15、25、39个弥散梯度磁场方向测量的胼胝体膝部FA值(F＝0.772,P＝0.465)及压部FA值(F＝1.804,P＝0.171)之间差异均无统计学意义,3个方向上胼胝体压部FA值均高于胼胝体膝部FA值.结论 对胼胝体纤维束的显示25个弥散梯度磁场方向扫描时间合理,既可保证扫描成功率,又可得到高质量的FA图像,实际应用意义较大.     

磁共振弥散张量纤维束成像在评估脑肿瘤白质纤维束变化中的价值

目的 探讨磁共振弥散张量纤维束成像(DTT)在评估脑肿瘤中脑白质纤维束变化的价值.方法 运用DTT技术分别评价胶母细胞瘤、脑膜瘤、间变性星形细胞瘤脑白质纤维束的变化.结果 脑肿瘤旁脑白质纤维束在DTT可有以下3种表现:(1)中断,(2)移位,(3)浸润.其中,在胶母细胞瘤中,可见脑白质纤维束中断, 其终止纤维可通过胼胝体;在脑膜瘤中,可见肿瘤压迫引起的脑白质纤维移位以及残存、被分离的纤维束;在间变性星形细胞瘤中,DTT表现为肿瘤原发部位脑白质纤维束中断以及肿瘤对轴突的浸润.结论 DTT的异常表现与肿瘤临床病理特征相关.     

人脑投射纤维弥散张量纤维束成像的初步研究

目的 利用弥散张量纤维束成像显示人脑内部分投射纤维的三维结构，探讨其与解剖学描述的一致性。资料与方法 对1名正常志愿者进行单次激发回波平面弥散张量成像，利用纤维束成像软件包显示人脑部分投射纤维的三维结构，观察重建的投射纤维与解剖学描述的一致性。结果 通过选择恰当的感兴趣区，设置不同的部分各向异性阈值、角度阈值、步长和体素长度内采样数目等参数，弥散张量纤维束成像可以清楚地显示皮质脊髓束、视放射、内侧丘系、小脑上脚、中脚和下脚等投射纤维的三维结构，显示结果与解剖学描述具有较好的一致性。结论 投射纤维纤维束成像的结果与解剖学描述具有较好的一致性，该方法是一种较可靠的研究人脑纤维连接的方法。     

磁共振扩散张量及纤维束示踪成像对脊髓疾病的研究进展

弥散张量成像通过观察组织中异常运动的水分子来检测白质病变,已被证实非常有效;弥散纤维束成像则是运用三维后处理方法重建纤维束走行图。本文综述了弥散张量成像和弥散纤维束成像在脊髓肿瘤,损伤,炎症等脊髓疾病的特点,此方法比传统磁共振更能敏感检出和显示脊髓疾病,必将在临床有更广阔的应用。     

白血病脑实质浸润的弥散张量成像应用研究

目的探讨1．5T磁共振弥散张量成像（diffusiontensorimaging,DTI）,部分各向异性（fractionalanisotropy,FA）和表观扩散系数（apparentdiffusioncoefficient,ADC）及弥散张量纤维束成像（diffusiontensortractography,DTT）在成人白血病脑实质浸润的应用价值。方法回顾性分析经临床证实的8例白血病脑实质浸润病例DTI之ADC、FA参数图,分别测量病变、水肿及健侧相应部位FA值和ADC值;观察各例在DTT图的变化。结果白血病脑实质浸润的肿瘤实质部分FA值8例全部较健侧降低,ADC值5例减低,3例增高;周围水肿区FA值全部降低,ADC值全部增高;脑白质纤维束DTT显示有中断、移位、浸润。结论DTI对脑侵犯神经纤维束损伤具有独特诊断价值;DTI的参数变化能够量化神经纤维受压后微细结构的变化,DTT图像重建能直观显示脑白质纤维束的完整性及损伤程度,DTI联合DTT可更加准确地评估白血病脑侵犯的损害程度。     

颈髓白质纤维束磁共振扩散张量成像的初步研究

目的:利用磁共振弥散张量成像(DTI)研究正常成人颈髓的各向异性程度,探讨颈髓白质纤维束成像的可能性和应用价值。方法:使用单次激发自旋回波平面回波(SE-EPI)序列对14例MR检查正常的健康志愿者行颈髓弥散张量成像检查。重建FA图,在颈髓各节段分别测量FA值。利用日本东京大学Masutani开发的DTVⅡ和VolumeOne纤维束示踪成像软件进行白质纤维束成像。结果:颈髓平均FA值0.6583±0.0737,所有FA图上颈髓显示清晰,没有明显图像失真。白质纤维束成像三维显示颈髓大部分主要的纤维束。结论:DTI有效地显示颈髓白质纤维的各向异性特征及白质纤维束的分布和走向,对颈髓疾病的研究提供了新的方法。     

Changes in brain water diffusion during childhood

We studied the changes in brain water diffusion in childhood as seen on diffusion-weighted MRI in 30 children from 1 day of life to 17 years to provide a data base and to investigate the correlation of diffusion changes with known patterns of white matter maturation. The apparent diffusion coefficient (ADC) and apparent anisotropy (AA) were calculated in numerous regions of the brain to include major white matter tracts and gray matter. ADC and AA values were directly related to the structural maturity and compactness of the white matter tracts and changed with aging in a way that predated early myelination markers such as signal change on T1- or T2-weighted images. Diffusion of water is sensitive to structural changes in the brain such as white matter maturation and may be useful in investigating white matter disorders. Received: 18 March 1999 Accepted: 25 March 1999     

MR imaging of the various stages of normal myelination during the first year of life

Summary The normal process of myelination of the brain mainly occurs during the first year of life. This process as known from histology can be visualized by MRI. Because of the very long T1 and T2 of immature brain tissue it is necessary to use adjusted pulse sequences with a long TR in order to obtain sufficient tissue contrast. With long TR SE images five stages can be recognized in the process of normal myelination and brain maturation. During the first month of life long TR short TE SE images show what are believed to be myelinated structures by correlation with published histological studies with a high signal intensity, unmyelinated white matter with a low signal intensity and gray matter with an intermediate signal intensity. The signal intensity of unmyelinated and myelinated white matter is reversed on long TR long TE SE images. In the course of a few weeks the signal intensity of unmyelinated white matter becomes high and the signal intensity of myelinated white matter becomes low also on long TR short TE SE images. These changes are believed to be caused by a loss of water and a change in chemical composition of brain tissue just prior to the onset of a wave of myelination. With progression of myelination the signal intensity of white matter changes from high to intermediate to low. These changes result in stages of isointensity, first in the central parts of the brain, later in the peripheral parts. At the end of the first year the adult contrast pattern is reached in all parts of the brain. IR images are also able to depict the progress of myelination, but appear to be less sensitive to subtle changes in the degree of myelination. The precise normal values for the five stages depend on the magnetic field strength and the pulse sequences used.     

MR扩散张量成像对脑肿瘤的初步应用研究

目的 :评价MR扩散张量成像在脑肿瘤中的应用价值。方法 :搜集经手术及病理证实的脑膜瘤和星形细胞瘤病例共 3 3例 ,行常规MRI、扩散张量成像 (DTI)检查。构建各向异性分数 (FA)图 ,并测量肿瘤及周围白质的FA值。结果 :正常白质纤维在FA图上表现为高信号。在肿瘤存在时 ,周围白质纤维可表现为受推压移位或浸润破坏 ,破坏后FA值降低 ,表现为低信号。这些表现在常规MRI上均未清楚显示。结论 :DTI可清楚显示肿瘤与周围白质纤维的解剖关系 ,指导临床制订手术方案。     

基于体素的形态测量学技术在视神经脊髓炎脑改变中的初步应用

目的 通过基于体素的形态测量学(VBM)技术研究视神经脊髓炎(NMO)患者的脑体积变化情况,初步从结构方面探讨NMO的脑损害模式.方法 对23例NMO患者和15名健康志愿者进行脑部3D快速扰相梯度回波(FSPGR)序列扫描.原始数据用统计参数图(SPM)5软件进行处理.采用t检验比较两组全脑体积的差别,应用Pearson相关分析评价全脑体积和年龄的相关性.结果 NMO组患者的全商灰质体积[(610.2±55.0)ml]明显小于健康对照组[(657.2±36.3)ml],差异有统计学意义(t=-2.915,P＜0.05).NMO患者的年龄[(40±9)岁]与脑灰质分数[(42.5±2.6)%]呈负相关(r=-0.673,P＜0.05).局部脑体积分析结果显示,与健康对照组相比,NMO灰质体积减少主要集中在左侧岛叶和双侧后扣带回,白质体积减少区主要位于左侧额叶和左侧顶叶皮层下白质.结论 VBM技术可以敏感地检测NMO的脑体积变化情况.NMO患者的脑体积较健康对照组有减少的趋势,以灰质萎缩更明显.

Abstract：

Objective To investigate the changes of brain volumes in neuromyelitis optica (NMO)patients using voxel-based morphometry (VBM) method, and preliminarily explore the pattern of cerebral anatomical impairment. Methods Twenty-three clinically defined NMO patients and 15 gender and age matched healthy volunteers underwent 3-dimensional (3D) fast spoiled gradient echo (FSPGR) sequence scanning on 3.0 Tesla MR systen. Raw data was processed and analyzed using statistical parametric mapping (SPM) 5. Whole brain volumes included grey matter volume (GMV), white matter volume (WMV), total intracranial volume (TIV), grey matter fraction (GMF), white matter fraction (WMF),brain tissue fraction (BTF) and regional brain volumes between the two groups were compared by independent samples t-test and an Pearson were performed to compare the regional brain volumes and the ages. Results GMV of NMO group[(610. 2 ± 55.0) ml] was significantly decreased comparing to healthy control group[(657. 2 ± 36. 3) ml] (t = - 2. 915, P ＜ 0. 05). The age of NMO patients [(40 ± 9) years old] showed negative correlation with GMF [(42. 5 ± 2. 6) %] (r = - 0. 673, P ＜ 0. 05). Regional brain volume analysis showed decreased GMV in left insula and bilateral posterior cingutates in NMO patients,while decreased WMV was found in left frontal and left parietal white matter. Conclusion VBM could detect brain volume changes sensitively. Total grey matter volume in NMO patients was decreased comparing to HC group. Regional grey matter atrophy in NMO patients occurred in left insular and bilateral posterior cingutates, regional white matter atrophy occurred in left frontal and left parietal lobe.     

Does diving damage the brain? MR control study of divers' central nervous system

Purpose:
To evaluate the prevalence of cerebral white matter changes on MR imaging in healthy elderly compressed air divers with a long diving history in comparison with control subjects who have never dived.
Material and Methods:
The investigation employed 59 experienced elderly divers and 48 control subjects matched for age, body mass index, alcohol and smoking history. MR studies included a fluid attenuated inversion recovery sequence and T1- and T2-weighted pre- and postcontrast images in axial orientation of the whole brain to localize white matter changes.
Results:
MR images did not show any morphologic abnormalities in the brains of divers. Both groups - divers and controls - did not differ significantly with respect to white matter changes of the brain.
Conclusion:
No increased prevalence of cerebral white matter changes in compressed air divers compared with a healthy worker sample of similar age were found. Thus, extensive compressed air diving may not necessarily be related to radiological changes on MR.     

Contrast between white and grey matter: MRI appearance with ageing

MRI contrast between white and grey matter appears to be higher in young normal subjects than in older patients. The aim of the present study was to investigate the possible relationships between these changes in contrast and ageing. It consisted of two parts. In the first part we retrospectively evaluated 140 MRI brain examinations of healthy subjects, 20 per decade (age range 20–90 years), in whom the contrast was subjectively scored. In the second part we prospectively measured the actual T1, spin density (SD) and T2 values of white and grey matter in another 22 healthy subjects (age range 20–80 years). In the first group of subjects a progressive decrease in white/grey matter contrast was observed with ageing. In the second group of subjects the T1, SD and T2 values of white matter were always shorter than those of grey matter. There is a close relation among T1, SD and T2 values of white and grey matter with ageing. We suggest that there is a progressive loss of white/grey matter contrast with ageing. Such a phenomenon is possibly due to an increased water content in the white matter and the progressive neuronal loss in the grey matter that occurs with age. Correspondence to: S. Magnaldi     

基于体素的形态测量学方法研究屈光参差性弱视患儿的相关区域脑结构

目的 利用基于体素的形态测量学(VBM)分析屈光参差性弱视患者全脑灰、白质体积变化.方法 采用1.5 TMR扫描仪对12例屈光参差性弱视患儿和年龄、性别相匹配的12名正常志愿者行3D快速扰相梯度回波(FSPGR)序列的全脑扫描.原始数据用统计参数图(SPM)5软件进行处理.结果 与正常对照组相比,弱视组脑灰质体积减少的脑区包括右侧楔叶、双侧枕中下回、右侧额中回、左侧颞中回、右侧颞上回、右侧楔前叶、右侧中扣带回(差异脑区体素＞ 10个).弱视组脑灰质体积增多的脑区包括右侧小脑半球、右侧海马旁回、左侧中央前回、左侧额上回(差异脑区体素＞ 10个).与对照组比较,弱视组脑白质体积减少的脑区包括双侧视放射区、双侧内囊,以右侧为著(差异脑区体素＞10).未见弱视组脑白质体积增多的脑区.结论 运用VBM方法可分析屈光参差性弱视患者全脑灰、白质体积变化,有助于从形态学的角度阐述屈光参差性弱视的可能神经机制.     

Age-related structural changes in the young adult brain shown by magnetic resonance diffusion tensor imaging

RATIONALE AND OBJECTIVE: Structure of the brain is generally thought to remain stationary over the course of young adulthood. However, there is some evidence that microstructural changes of the brain do occur during this period. Magnetic resonance diffusion tensor imaging (DTI) provides quantitative measures of structural changes in the brain. We used DTI to detect possible age-related structural changes in the brains of young adults. MATERIALS AND METHODS: Twenty-five healthy adults in their 20s and 30s were studied using DTI. Maps of mean diffusivity and fractional anisotropy (FA) were created for subsequent histogram and region-of-interest analyses, and the results were correlated with the respective ages of the subjects. RESULTS: The histogram analysis revealed a significant increase in the mean FA value (r = 0.407, P < .05) and a significant decrease in FA peak height (r = -0.578, P < .002) with increasing age. No age-related changes were observed in indices derived from mean diffusivity maps. Region-of-interest analysis showed no focal white matter regions with significant FA change. CONCLUSION: Quantitative DTI revealed age-related structural changes in the brains of young adults. Changes on FA histograms observed in this study were considered to be related to changes in the relative volumes of gray and white matter and may represent maturational changes.     

Peritumoral brain edema in intracranial meningiomas evaluated by dynamic perfusion-weighted MR imaging: a preliminary study

Our objective was to semi-quantitatively evaluate the cerebral perfusion in the peritumoral brain edema of meningiomas using dynamic perfusion-weighted MR imaging. Six patients with intracranial meningiomas accompanied by peritumoral brain edema were prospectively examined by perfusion-weighted MR imaging. One patient was examined twice, once before and once 5 months after the surgical resection. The relative regional cerebral blood volume (rrCBV), the relative regional cerebral blood flow (rrCBF), and the relative regional mean transit time (rrMTT) were calculated for peritumoral brain edema and the contralateral white matter. These parameters were compared between peritumoral brain edema and the contralateral white matter. The time–concentration curve of the peritumoral brain edema was less prominent than that of the contralateral white matter, resulting in a significantly lower rrCBV (mean 46%) and rrCBF (mean 45%) in peritumoral brain edema than those of contralateral white matter. The serial perfusion-weighted MR imaging also demonstrated the recovery of these parameters after the removal of meningioma by means of surgical resection. Perfusion-weighted MR imaging can demonstrate significantly decreased rrCBV and rrCBF in peritumoral brain edema compared with those in normal white matter. Electronic Publication     

多系统萎缩弥散张量成像的基于体素分析

目的 利用基于体素的分析方法对震颤麻痹型多系统萎缩(MSA-P)患者的弥散张量成像(DTI)数据进行研究,探索其脑内微结构改变.资料与方法 入组24例MSA-P患者(病例组)及26例健康志愿者(对照组),分别行全脑结构成像及弥散张量成像.比较两组各向异性分数(FA)图和平均扩散率(MD)图,得出反映病例组与对照组差异的统计参数图.结果 与对照组相比,病例组FA值减低累及双侧脑干、小脑半球、岛叶、顶叶、额叶、颞叶及枕叶,差异有统计学意义(P＜0.005),其中白质受累较灰质显著;MD值在双侧脑干、小脑半球、基底节、岛叶、额叶、颞叶及枕叶处较对照组升高,差异有统计学意义(P＜ 0.005).结论 DTI技术可以敏感地通过显示MSA-P患者脑内微结构的改变反映其受累情况,基于体素的分析方法有助于客观展示全脑受累情况.