局灶性脑皮层发育不良的MRI诊断

目的 研究局灶性脑皮层发育不良(focal cortical dysplasia,FCD)的MRI表现特点.资料与方法 回顾性分析23例经手术病理证实的FCD患者的MRI表现.常规行横断位、矢状位及垂直于海马长轴的斜冠状位扫描,获得T1 WI、T2WI及液体衰减反转恢复序列(FLAIR)图像.结果 23例FCD病灶均表现为一侧大脑半球内局限性病变.病灶区域皮质增厚18例,灰白质分界模糊20例,皮层下白质异常信号22例,脑回、脑沟形态异常14例,邻近蛛网膜下腔局限性扩大4例.T1WI、T2WI及FLAIR显示灰白质分界模糊分别为6例、20例及18例;皮层下白质异常信号分别为3例、16例及19例;脑回、脑沟形态异常分别为12例、10例及11例.结论 FCD的MRI表现为皮质增厚、灰白质分界模糊、皮层下白质异常信号、脑回、脑沟形态异常及邻近蛛网膜下腔局限性扩大.T2WI及FLAIR显示灰白质界限、白质内异常信号较T1WI敏感,T1WI显示脑回、脑沟形态有一定的价值.     

磁共振脑表面三维重建技术在脑表面病变定位中的价值探讨

目的 评价磁共振脑表面三维重建技术在脑表面病灶精确定位诊断中的价值.方法 病例共23例,其中肿瘤15例、陈旧脑梗塞软化病灶5例、血管畸形2例、脑发育畸形1例.使用容积重建技术进行磁共振脑三维重建并暴露脑表面结构.脑表面三维重建图像和二维多平面重建图像请2位有经验的放射诊断医师和2位年轻进修医师分别判读,对病灶累及的脑叶做出定位诊断.结果 基于二维多平面重建图像,4位医师共认定23例病灶累及脑回(沟)118个,其中定位一致的脑回(沟)8个(6.78%),仅有1位医师认定的脑回(沟)51个(43.22%);基于脑表面三维重建图像,共认定脑回(沟)93个,定位一致的脑回(沟)16个(17.2%),仅有1位医师认定的脑回(沟)28个(30.11%),差异有统计学意义.2位有经验医师分别基于二维多平面重建图像和脑表面三维重建图像进行病灶定位诊断时,定位一致的比例从50%提高到59.7%;2位年轻进修医师分别基于二维多平面重建图像和脑表面三维重建图像进行病灶定位诊断时,定位一致的比例从16.4%提高到32.1%,后者差异有显著性.结论 脑表面三维重建技术能清楚显示病灶位置及其与脑沟、脑回的关系.     

适于磁共振检测播散性皮层抑制的猫脑解剖研究

目的 寻找适于研究播散性皮层抑制的猫脑表面脑回及磁共振功能成像(fMRI)平面.材料与方法 成年雌性家猫6只,行垂直相交的高分辨力横断面、矢状面、水平面T1WI及T2WI,研究各方位图像显示脑回的解剖特点.灌注固定后取猫脑标本进行大体表面解剖观察,分析各脑回的位置及形态特点.结果 猫脑具有多脑回结构.边缘回内侧紧邻上矢状窦;上侧裂回位置相对表浅,与相邻脑回以脑沟相隔,周围无大血管相邻;外侧裂回位置偏外,长度短,形态复杂.在MRI上每个横断面仅能显示嘴尾侧走行脑回的一个断面,矢状面不能显示相邻脑回间的关系,包括双侧上侧裂回和边缘回的水平面图像既能显示脑回的长轴,又能显示相邻脑回的关系且能提供对侧大脑半球作为对照.结论 上侧裂回是研究播散性皮层抑制最合适的皮层结构;包括双侧上侧裂回和边缘回的水平面是fMRI研究播散性皮层抑制的理想成像层面.     

透视触发三维快速梯度回波技术在颅内静脉成像的应用

目的探讨透视触发血管成像技术在脑静脉系统疾病诊断中的价值。方法使用三维快速梯度回波技术（Flash 3D）序列透视触发血管成像,通过调节扫描参数、薄层、高像素,并减少造影剂量等方法,对50例临床怀疑脑内静脉系统病变的患者进行对比增强静脉成像,并评价所获影像中血管主干及分支解剖显示情况。结果50例临床怀疑脑内静脉系统病变患者均成功完成了透视触发Flash 3D序列扫描血管成像,均能满意地显示血管影像,12例未见异常,脑静脉血栓4例,静脉型血管瘤19例,动脉静脉畸形6例,血液病浸润2例,肿瘤压迫及侵犯7例。结论Flash 3D对比增强血管成像能清楚地显示脑部静脉系统及其与病变的关系,为临床对疾病的诊断和治疗提供依据。     

磁共振脑表面成像技术及临床应用

脑表面结构如脑沟、脑回、脑裂等走行方向和形态变异较大，常规磁共振断面影像难以显示上述结构的全貌。介绍了常用的磁共振脑表面成像技术及其在临床研究中的应用价值。     

基于MR三维梯度回波与扩散加权成像序列的脑表面重组技术比较

目的 使用MR三维梯度回波（3D flash）序列和扩散加权成像（DWI）序列的扫描图像进行脑表面三维重组，对两种方法显示脑表面结构的能力、价值与限度及临床应用等进行比较和探讨。方法 对30名正常人行头颅3D flash和DWI检查。通过容积重组显示脑表面解剖结构。同一组医生对两种方法重组图像进行评价和评分，并比较结果。结果 基于3D flash重组的各脑表面结构清楚显示，平均得分均在2．50分以上。基于DWI的重组图像能够较好地显示中央前回、中央后回、顶上小叶、额上回、中央前沟、中央沟、中央后沟、顶间沟及额上沟等结构，平均得分2．60～2．75分，缘上回、角回、额中回、额下回、颞上回、外侧沟和额下沟等结构显示较差，平均得分1．67～2．48分，颞中回、颞下回、颞上沟及颞下沟等显示很差，平均得分仅0．88～1．27分。比较两种方法的平均得分，基于3D flash重组优于基于DWI的三维重组，差异有统计学意义，P值均〈0．01。结论 基于3D flash重组能够显示真实的脑表面主要脑沟、脑回和脑裂，对脑解剖形态的研究和定位诊断有重要意义。基于DWI的三维脑表面重组能比较满意地显示顶叶、额叶的主要表面结构，扫描和重组快速，有一定实用价值。     

磁共振脑表面成像技术及临床应用

脑表面结构如脑沟、脑回、脑裂等走行方向和形态变异较大,常规磁共振断面影像难以显示上述结构的全貌.介绍了常用的磁共振脑表面成像技术及其在临床研究中的应用价值.     

Rasmussen脑炎的MRI诊断

目的 总结Rasmussen脑炎的MRI特点,提高对本病影像表现的认识.方法 回顾性分析10例Rasmussen脑炎患者的MR图像,男7例、女3例,平均年龄(11±4)岁.常规行横断面、矢状面及垂直于海马长轴的斜冠状面扫描,获得T1WI、T2WI及液体衰减反转恢复(FLAIR)序列图像.评估Rasmussen脑炎患者术前MR检查中脑萎缩和信号情况,以及上述改变在随访时MR的表现.结果 Rasmussen脑炎的影像特点为:(1)脑萎缩性改变:患侧侧脑室体部扩大(8/10),颞角扩大(9/10),外侧裂增宽(9/10),局部脑沟增宽和脑回变小(7/10),尾状核和壳核萎缩(6/10).病变晚期皮层萎缩多为半球性或累及2个以上脑叶.(2)信号改变:皮层或皮层下长T2信号(9/10),多累及2个以上脑叶.(3)病变进展性:8例接受随访MR的患者均可见病变侧半球的萎缩性改变加重,范围加大,由局部向半球性发展;皮层信号改变较大.结论 Rasmussen脑炎好发于儿童,表现为一侧大脑半球进展性萎缩改变,脑室扩大,外侧裂和脑沟增宽,脑回变小,伴有相应部位的皮层萎缩和皮层T2高信号,深部灰质核团也可受累.     

新生儿和婴儿期Sturge-Weber综合征的CT诊断

目的:探讨新生儿和婴儿期Sturge-Weber综合征的CT表现。方法:回顾性分析1例新生儿期和7例婴儿期Sturge-Weber综合征患儿的临床和CT资料,均行常规CT平扫,其中5例同时行增强CT。结果:8例均有面部三叉神经分布区皮肤血管瘤,4例患儿出现患侧皮层钙化,4例未出现皮层钙化的患儿显示受累脑实质密度略增高,伴灰白质分界不清。8例患儿均表现为局部脑外间隙增宽及脑沟增宽等脑萎缩样改变,3例随访患儿出现脑萎缩。5例行增强扫描的患儿出现脑回样强化,4例患侧的侧脑室脉络丛增大,1例双侧Sturge-Weber综合征于10个月随访时出现双侧脉络丛增大。结论:CT对新生儿和婴儿期Sturge-Weber综合征的诊断有重要价值。     

神经元移行异常的CT诊断(附30例报告)

目的:探讨神经元移行异常的CT表现特点,以进一步提高其诊断准确性。方法:回顾分析近两年经本院确诊的30例神经元移行异常病例的临床和CT资料,总结各类病变的CT表现特征。结果:30例中,灰质异位8例,脑裂畸形6例(其中5例伴多小脑回或巨脑回畸形,所有病例均伴透明隔缺如),多小脑回畸形或巨脑回20例(其中5例伴脑裂畸形),单侧巨脑畸形1例。灰质异位表现为白质内团块状、室管膜下结节状或条带状灰质密度灶;脑裂畸形表现为从侧脑室壁到脑表面贯穿大脑半球的裂隙,表面覆盖灰质,可分为开唇型和闭唇型;多小脑回或巨脑回表现为广泛或局限性的皮质增厚,边缘呈波浪状,灰白质交界光滑,脑沟浅,白质减少;单侧巨脑畸形表现为一侧大脑半球及颅腔增大。结论:CT能够良好显示脑神经元移行异常的病理特征,有助于临床准确诊断。     

胎儿主要器官的正常解剖及MR表现

目的了解胎儿主要器官的正常解剖及MR表现。方法对47例胎儿行快速MR成像检查，使用序列为单次激发快速自旋回波序列，观察主要正常器官的解剖和MR表现，包括脑、肺、心脏、肝、脾、胃肠道、肾脏、膀胱、骨骼、脊柱和皮下脂肪，并按不同的胎龄分组观察。结果47例胎儿MR检查结果表明：孕20周时，胎儿各主要器官均已发育。20周左右，大脑皮层光滑，无脑回、脑沟，之后脑回、脑沟逐渐缓慢形成；肺、气管、支气管均呈高信号，心脏、大血管及肝脾呈低信号，胃肠道、肾孟肾盏、膀胱呈高信号，肾实质为等信号，骨骼、肌肉呈低信号；脊柱20周已形成，皮下脂肪20周可见，随胎龄增长逐渐增多。结论快速MR成像能清楚显示胎儿各主要器官的正常解剖和发育变化，胎儿主要器官的解剖和MR表现与新生儿有较大的差别。     

神经元移行异常的MRI诊断

目的分析各种神经元移行异常的MRI特征。方法分析50例神经元移行异常的MRI表现,总结MRI影像特征。结果灰质异位23例,脑裂畸形12例,多小脑回9例,巨脑回5例,无脑回1例。脑灰质异位MR表现为皮质下,白质区,侧脑室室管膜下结节状、团块状或带状病灶,在所有序列上与正常脑灰质信号相同。脑裂畸形表现为大脑半球的横行裂隙,边缘衬有灰质。多小脑回畸形表现为脑回增多、细小而浅。巨脑回畸形表现为脑回增宽,灰质增厚,白质变薄。无脑回畸形表现为大脑半球呈肾形,正常脑沟和脑回消失,皮质增厚,白质变薄。结论MRI是诊断神经元移行异常的最佳影像方法。     

MR imaging of brain surface structures: surface anatomy scanning (SAS)

Summary MR imaging technique that permits direct and non-invasive visualization of brain surface structures (Surface Anatomy Scanning, SAS) was developed using the combination of long TE, long TR spin echo sequence and thick slice. Clinical trials in 67 patients with SAS showed excellent visualization of the sulci and the gyri on the lateral, occipital, frontal and parietal surfaces of the brain together with cortical and subcortical lesions. The results indicate that the SAS is useful for the localization of cortical and subcortical pathology, for the diagnosis of anomalous gyral patterns, and for surgical planning.     

Analysis of the cerebral cortex in holoprosencephaly with attention to the sylvian fissures

BACKGROUND AND PURPOSE: Analysis of specific features in the brain of patients with holoprosencephaly (HPE) may clarify normal and abnormal brain development and help predict outcomes for specific children. We assessed sulcal and gyral patterns of cerebral cortex in patients with HPE and developed a method of grading brain development. METHODS: Neuroimaging studies (75 MR imaging, 21 CT) of 96 patients with HPE were retrospectively reviewed, with specific attention paid to the cerebral cortex. Thickness of cortex, width of gyri, and depth of sulci were assessed subjectively and by measurement. The angle between lines drawn tangential to the sylvian fissures ("sylvian angle") was measured in each patient with HPE and in 20 control patients. RESULTS: Thickness of cortex was normal in all 96 patients. Gyral shape and width and sulcal depth were normal in 80 patients. Twelve patients, all with very severe HPE and microcephaly, had reduced sulcal depth, diffusely in eight and limited to the anteromedial cortex in four with lobar HPE. Four patients had subcortical heterotopia, located anterior to the interhemispheric fissure, associated with shallow sulci in the overlying cortex. Sylvian fissures were displaced further anteriorly and medially as HPE became more severe, until, in the most severe cases, no sylvian fissures could be identified. Sylvian angle measurements corresponded closely with severity of HPE, being largest in the most severe and smallest in the least severe cases. All patients with HPE had sylvian angles significantly larger than the mean of 15 degrees measured in the control patients. CONCLUSION: The only true malformations of cortical development were subcortical heterotopia. However, diffuse and focal abnormal sulci were observed. We propose our sylvian angle measurement of extent of frontal lobe development as an objective means of quantifying the severity of HPE.     

Diffusion anisotropy in subcortical white matter and cortical gray matter: changes with aging and the role of CSF-suppression

PURPOSE: To determine the relevance of cerebrospinal fluid (CSF)-suppression for the measurement of diffusion anisotropy in well-localized areas of the brain, particularly the subcortical white matter (WM) within the gyri and cortical gray matter (GM), in young and elderly subjects, and to assess the changes of water diffusivity in the brain with normal aging. MATERIALS AND METHODS: Quantitative measures of anisotropy in 26 regions, including subcortical WM (i.e., in the gyri), cortical GM, major deep WM, and deep GM regions of young (21-25 years, N = 8) and elderly (61-74 years, N = 10) normal volunteers, were assessed with CSF-suppressed diffusion tensor imaging (DTI) relative to standard DTI. RESULTS: CSF-suppressed DTI demonstrated significant increases in fractional anisotropy (FA) of 3-12% in the young and 2-14% in the elderly groups with the largest changes being in the subcortical WM of the gyri. Furthermore, FA decreased by 10-19% in the subcortical WM of the gyri of the elderly subjects relative to the young, primarily due to increases in the perpendicular diffusivity, lambda(3), with age. CONCLUSION: CSF-suppressed DTI yields more accurate measures of quantitative anisotropy in cortical and subcortical brain regions. Reductions of anisotropy with aging were predominantly observed in subcortical WM of the gyri.     

Identification of pre- and postcentral gyri on CT and MR images on the basis of the medullary pattern of cerebral white matter

The authors illustrate a new method to identify the pre- and postcentral gyri on computed tomographic (CT) and magnetic resonance (MR) images of the brain on the basis of the pattern of the medullary branches of the cerebral white matter. The most commonly used method to identify the gyri depends on recognition of the central sulcus by surface arrangement of the sulci. The two methods were compared by analysis of CT images of 104 subjects who had normal findings (age range, newborn to 60 years; 57 males and 47 females). The usefulness of the new method was also determined in angiographic studies of nine patients with space-occupying lesions. The method is especially helpful for identification of gyri on the lower level of the centrum semiovale and if space-occupying lesions are present that may result in a blurred depiction of sulci. Since MR imaging depicts the medullary branches more clearly than does CT, this new method should facilitate identification of the gyri with either modality.     

The parasagittal line: an anatomic landmark for axial imaging

BACKGROUND AND PURPOSE: No validated imaging landmark exists for characterizing the medial-lateral position of abnormalities at the high convexity-parasagittal region. Our understanding of the courses and deflections of the upper cerebral sulci is limited. Our purpose, therefore, was to define a frontooccipital line with reproducible anatomic relations to the upper cerebral gyri and sulci and to validate that line for use as an anatomic landmark by specific analysis of the gyral-sulcal relationships along it. METHODS: In 100 subjects of all ages, the gyri and sulci visualized on serial axial CT sections of the upper brain were traced onto a single flat surface to delineate the anatomic relationships among the midline interhemispheric fissure, the paramedian superior frontal sulci (SFS) and intraoccipital sulci (IOS), the medial surface sulci, the high convexity sulci, and the inner table of the skull. These tracings provided a template for drawing a straight, best-fit parasagittal line from the SFS to the IOS and for assessing how reproducibly key anatomic structures align along the parasagittal line. To assure the applicability of the line to MR imaging, selected relationships were retested on serial axial MR sections in the same subjects. RESULTS: The parasagittal line could be drawn in each case and showed reproducible alignment with the SFS, hand-motor area, partes marginales, pars deflections, postcentral "parentheses," distal intraparietal sulci, and IOS. In supraventricular sections, the parasagittal line separated the sulci arising along the medial surface from those arising along the convexity. CONCLUSION: Because the anatomic relationships of the parasagittal line are reproducible, it may serve as a reference line or landmark. The tendency of this line to demarcate medial sulci from convexity sulci suggests immediate application to the definition of vascular territories and vascular watersheds, a topic under active investigation.     

MRI of focal cortical dysplasia

We studied nine cases of focal cortical dysplasia (FCD) by MRI, with surface-rendered 3D reconstructions. One case was also examined using single-voxel proton MR spectroscopy (MRS). The histological features were reviewed and correlated with the MRI findings. The gyri affected by FCD were enlarged and the signal of the cortex was slightly increased on T1-weighted images. The gray-white junction was indistinct. Signal from the subcortical white matter was decreased on T1- and increased on T2-weighted images in most cases. Contrast enhancement was seen in two cases. Proton MRS showed a spectrum identical to that of normal brain. Received: 10 September 1997 Accepted: 6 January 1998