出血性脑梗死的MRI特征性表现及其分型

目的：探讨出血性脑梗死（HI）的MRI特征性表现和分型。方法：采用1．5T MR,对50例HI行常规序列扫描（T1WI、T2WI、FLAIR）。必要时行MRA（42例）、增强扫描（4例）及T2＊WI（27例）。结果：根据梗死、出血的形态、部位进行MRI分型。Ⅰ型：脑叶HI：22例（44．0％）脑回状、斑片状出血位于皮层和／或皮层下白质。Ⅱ型：脑深部（基底节及丘脑）HI：17例（34．0％）;Ⅲ型：小脑HI：14例（28．0％）;斑片状、线状出血位于梗塞区内、边缘。混合型（Ⅰ型＋Ⅱ型）：3例（6％）。T2＊WI呈低信号。结论：HI的MRI表现有一定特征性,与脑梗死部位、面积有密切关系。新的MRI分型有助于对HI发生机制的理解,从而指导临床治疗。T2＊WI有助于HI的检出。     

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.     

局灶性脑皮质发育不良病理分型的MRI特点

目的探讨不同病理分型的局灶性脑皮质发育不良（FCD）的MRI特点。方法回顾分析行癫痫手术治疗后病理符合FCD患者的临床资料，所有患者术前均行MR检查。根据Palmini的FCD分型标准，分型后分别总结患者的MRI特点。结果共28例患者符合标准，其中FCDⅠ型与Ⅱ型各14例。FCDⅠ型患者中，9例病灶位于颞叶，6例合并海马硬化。其中MRI表现异常者8例，表现为灰白质交界不清，局部皮层增厚、形态异常等特征；FCDⅡ型患者中，病灶位于额叶7例，2例合并海马硬化。其中MRI表现异常者11例，多表现为脑回形态异常，液体抑制反转恢复序列（FLAIR）、T2WI上白质信号增高，以及白质内条带状异常增高信号向脑室方向延伸等特点。结论不同病理分型的FCD在MRI上表现的特点有所不同，了解这些特点有助于提高癫痫外科术前评估的准确性以及对手术预后的判断。     

儿童神经元移行异常性脑回畸形的CT表现

目的分析神经元移行异常所引起的脑回发育畸形的CT表现。材料和方法回顾性分析20例神经元移行异常脑回畸形的CT表现。结果20例中,无脑回畸形3例,非无脑回畸形17例。前者表现为普遍性脑皮质均匀增厚,无脑沟形成或仅有少而浅的脑沟,脑表面光滑,脑回宽而扁平。后者表现为非普遍性脑皮质不均匀增厚,增厚皮质边缘高低不平,呈小波浪状或结节状隆起,增厚的皮质向深部折迭,形成皮质裂,部分病例白质内见胶质增生。结论CT能够鉴别无脑回畸形和非无脑回畸形,为外科治疗由此而引起的难治性癫痫手术方案的选择提供依据。     

脑真菌感染的MRI表现

目的探讨脑内真菌感染的MRI表现。方法回顾性分析6例诊断为脑真菌感染患者的MRI形态及信号表现特征。结果6例脑内真菌感染MRI均有清晰显示,其中2例为单发,位于额叶皮层和皮层下;4例为多发病变,位于半球脑皮层、皮层下、深部白质和基底节区,呈多发斑片状。MRI T 1WI均呈等低信号,T 2WI均呈周围高中间稍低信号,DWI呈等和稍高信号;MRI增强检查病灶表现为斑片状、不规则环状或脑回样较明显强化,病灶中心坏死区均无强化。结论脑内真菌感染临床和影像缺少特异性,但部分患者MRI如果表现为多发,累及范围较大,T 2WI呈周围高中间低信号、DWI呈等或稍高信号,MRI增强检查表现为斑片状、不规则环状或脑回样较明显强化,应考虑到本病。     

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。     

儿童多发性硬化的临床特点及MRI特征

目的 探讨中国儿童多发性硬化(MS)的临床孤立综合征( CIS)和复发时的临床及MRI特征.方法 回顾性分析16例MS患儿的首次发作及复发时临床及影像学资料.随访时间4个月至7年,期间患儿复发次数为1～5次.由1名儿科神经医师对CIS及复发的临床表现进行了归类总结.由1名资深神经影像学医师对患儿CIS及复发的头颅MRI表现进行分析,内容包括病灶的位置、大小、分布.病灶位置的分析包括皮层、皮层下白质、中央白质、脑室旁白质、深部灰质核团以及脑干和小脑.结果 (1)临床表现:儿童MS发病急,CIS以皮层症状及视觉障碍表现多见,14例1年以内复发,复发时皮层症状减少,而视觉症状仍较多,随访时康复良好.(2)颅脑MRI表现:CIS时,13例出现皮层下白质病灶,且大片融合,与中央白质病灶相连,好发部位依次为额、顶叶.皮层9例受累.10例可见中央白质病灶.6例可见脑室旁白质小病灶.4例可见对称性深部灰质核团病灶.5例可见脑干病灶.3例可见小脑病灶.3例可见视束或视神经肿胀、增粗.2例可见锥体束异常信号.1例可见胼胝体病灶.复发时,12例可见皮层下病灶,较CIS时数量增多,以小病灶为主.9例可见中央白质病灶,病灶大小较前减小.8例可见脑室旁病灶,病灶数量较CIS时增多.仅有2例出现皮层病灶.5例出现小脑病灶.4例可见脑干病灶.6例可见锥体束病灶,发生率较CIS时明显增多,且出现“轨道征”.结论 儿童MS的MRI表现具有一定特征,CIS时额、顶叶皮层下白质病灶融合成大片并常累及中央区白质,复发时有时可见“轨道征”,结合临床可以提高对儿童MS诊断的正确性.     

新生儿缺氧缺血性脑病的MRI表现

目的:探讨新生儿缺氧缺血性脑病(HIE)的MRI表现。材料和方法:对87例临床确诊为HIE的患儿行MRI扫描,并对其MRI表现进行分析。结果:87例HIE患儿中,74例(85.1%)可见皮层、皮层下及深部白质T1WI迂曲条状、点状高信号;69例(79.3%)显示基底节、丘脑T1WI异常高信号及内囊后肢高信号消失;62例(71.3%)出现弥漫性脑水肿;58例(66.7%)可见颅内出血,包括蛛网膜下腔出血、硬膜下出血、脑室内出血及脑实质出血;19例(21.8%)可见侧脑室周围白质软化;7例(8.0%)可见脑梗死。结论:MRI在HIE正确诊断和早期治疗中具有重要临床价值。     

病毒性脑炎与急性播散性脑脊髓炎的MRI鉴别

目的　探讨病毒性脑炎与急性播散性脑脊髓炎(ADEM)脑部MRI表现及鉴别两种疾病的可能性。 资料与方法　分析47例病毒性脑炎及43例ADEM病例的脑部MRI表现,按疾病分组,分析病灶的分布区域、大小、数目、强化的范围及形态的差别。 结果　病毒性脑炎脑内有多发或单发的对称或不对称大片状病灶,主要位于皮层、皮层下及基底节 丘脑区,MRI呈长T1 长T2 信号,增强扫描22例,显示病灶强化者11例,其中呈大片状或脑回状强化者7例。ADEM中脑内有多发对称或不对称斑片状病灶,主要位于双侧脑室周围及额颞顶枕叶白质区,MRI呈长T1 长T2 信号,增强扫描18例,显示病灶强化,呈环形或斑点状强化者13例。两种疾病在病灶的分布区域、大小、强化的范围及形态存在差异(P<0.05);病灶的数目无明显差异(P>0.05)。 结论　综合分析病毒性脑炎及ADEM病例的脑部MRI表现,MRI可在一定程度上为临床的鉴别诊断、治疗方案、治疗监测及评估预后提供依据。     

病毒性脑炎的MRI诊断

目的探讨病毒性脑炎MR I表现特点及与急性播散性脑脊髓炎(ADEM)鉴别的可能性。方法分析56例病毒性脑炎及50例ADEM的脑部MR I表现,重点分析病毒性脑炎的脑部MR I表现。结果病毒性脑炎脑内有多发或单发的对称或不对称大片状病灶,主要位于皮层、皮层下及基底节-丘脑区,MR I呈长T1长T2信号,增强扫描27例,显示病灶强化者17例,其中呈大片状或脑回状强化者10例。ADEM则脑内有多发不对称斑点、斑片状病灶,主要位于双侧脑室周围及额颞顶枕叶脑白质区,MR I呈长T1长T2信号,增强扫描20例,显示病灶强化者15例,均为环形或斑点状强化。结论MR I是诊断病毒性脑炎重要的辅助检查方法,可在一定程度上为临床的早期诊断及鉴别诊断提供依据。     

SWI在脑微出血与急性期脑梗死后出血转化的相关性研究

目的探讨急性脑梗死脑出血转化(HT)与微出血(CMBs)的相关性。方法回顾性分析发病在24 h内经临床及扩散加权成像(DWI)确诊的急性期脑梗死患者资料72例,根据磁敏感加权成像(SWI)图像梗死灶内是否出现极低信号分为梗死后出血转化组(HT组)和单纯脑梗死组(对照组)。同时对病灶以外CMBs经两名影像学医师诊断记为CMBs阳性共32例,其中对照组24例(24/62,38.7%),HT组8例(8/10,80%)。根据CMBs分布分为脑叶组和脑深部组,对照组脑叶8例(8/24,33.33%),脑深部16例(16/24,66.67%)。HT组脑叶7例(7/8,87.5%),脑深部1例(1/8,12.5%)。结果两组CMBs检出率及发生部位差异均有统计学意义(P值<0.05)。结论梗死后HT与CMBs的发生率和发生部位相关,SWI可检出CMBs,预示微血管的出血倾向,预测急性期脑梗死HT的危险性,进而为溶栓治疗提供可能的依据。     

儿童线粒体脑肌病的MRI表现

目的回顾性研究20例线粒体脑肌病患儿(年龄10个月到14岁)的MRI表现.方法20例由肌肉活检及实验室检查证实为线粒体脑肌病的患儿,脑内均有MRI阳性表现,研究其MRI表现的类型.结果20例患儿脑内病灶均表现为T1WI低、T2WI高信号,8例有不同程度的脑萎缩.18例患儿主要为灰质受累,其中10例为只有深部灰质病变;4例为深部灰质和大脑皮质同时受累.4例为深部灰质病变合并脑梗塞而同时累及灰质和白质.2例主要为白质受累,表现侧脑室后角旁白质异常信号.结论儿童线粒体脑肌病的MRI表现是多样性的.当儿童脑MRI表现为灰质(尤其是深部灰质)异常信号、灰质萎缩、不典型梗塞、不典型白质病变且合并临床难以解释的神经、肌肉等多系统的症状时,应考虑到线粒体肌病的可能.     

MR imaging and histologic features of subinsular bright spots on T2-weighted MR images: Virchow-Robin spaces of the extreme capsule and insular cortex

PURPOSE: To determine the cause and frequency of high-signal-intensity foci detected in the insular cortex and extreme capsule on thin-section, high-spatial-resolution, coronal, T2-weighted magnetic resonance (MR) images. MATERIALS AND METHODS: The authors assessed high-signal-intensity areas in the insular cortex and extreme capsule on coronal MR images obtained in 56 patients with seizure and five control subjects. Images were obtained with thin-section, high-spatial-resolution, T2-weighted, fast spin-echo; three-dimensional, spoiled gradient-recalled-echo; and fluid-attenuated inversion-recovery sequences. In two formalin-fixed brain specimens, MR imaging findings were correlated with gross anatomic and histologic findings. RESULTS: Subinsular bright spots were found in 53 of the 56 (95%) patients (96 of 112 [86%] hemispheres) and all five control subjects. The spots were elliptical in 30 patients, round in 14 patients, linear in 22 patients, and dotlike in seven patients and often had a featherlike configuration. The spots were isointense to cerebrospinal fluid on T2-weighted, fast SE images and were located in the anterior extreme capsule white matter and insular cortex. MR imaging of brain specimens revealed bilateral elliptical areas of high signal intensity that corresponded to small multiple cavities at gross anatomic inspection. At microscopic examination, these cavities were perivascular spaces of mostly arteriolar origin. CONCLUSION: High-signal-intensity subinsular foci at MR imaging are due to enlarged perivascular spaces. In most cases, these foci can be visualized on thin-section, high-spatial-resolution, coronal T2-weighted images; they should not be mistaken for pathologic conditions when they occur unilaterally.     

Evaluation of image quality and lesion detectability on I-123 IMP brain SPECT

Influence of image quality on lesion detectability in I-123 IMP brain SPECT was discussed in forty-two cases with various cerebrovascular disorders. Fifty nine lesions, which were considered to show decreased uptake of I-123 IMP, were analyzed in this study. In all cases, SPECT examinations were started within 30 minutes after intravenous administration of 3 mCi of I-123 IMP. To determine the lesion detectability, fourteen radiologists from nine hospitals were gathered and film reading was carried out. To classify the image quality into valuable or not, findings of five points on SPECT image were visually evaluated; 1) uniformity of cortex accumulation, 2) separation of bilateral visual cortices, 3) density of white matter, 4) separation between basal ganglion and thalamus, 5) density of basal ganglion and thalamus. Mean lesion detections were 10.3/14 for the lesions of cerebral cortex, 9 for cerebellum, 3.58 for white matter and 3.22 for basal ganglion and thalamus, respectively. The detectability was certainly influenced by the image quality in the lesion of basal ganglion and thalamus, white matter and single lobe of cerebral cortex. We concluded that detection of small lesions and deep lesions with I-123 IMP SPECT was dependent on the image quality and the proposed classification of I-123 IMP SPECT image was useful for evaluating image quality from the points of view of the lesion detectability.     

The spectrum of brain MR abnormalities in sickle-cell disease: a report from the Cooperative Study of Sickle Cell Disease.

PURPOSETo define the spectrum of abnormalities in sickle-cell disease, including infarction, atrophy, and hemorrhage, that are identified by brain MR imaging.METHODSAll MR studies included T1, T2, and intermediate pulse sequences. Images were interpreted without knowledge of the clinical history or neurologic examination findings. Brain MR imaging was performed in 312 children with sickle-cell disease.RESULTSSeventy patients (22%) had infarction/ischemia and/or atrophy, infarction/ischemia was noted in 39 children (13%) who had no history of a stroke (the "silent" group). The prevalence rates for silent lesions were 17% for sickle-cell anemia and 3% for hemoglobin sickle-cell disease. For patients with sickle-cell anemia and a history of cerebrovascular accident, infarction/ischemia lesions typically involved both cortex and deep white matter, while silent lesions usually were confined to deep white matter. Within the age range studied, the prevalence of infarction/ischemia did not increase significantly with age, although older patients with lesions had more lesions than did younger patients with lesions.CONCLUSIONSBrain MR imaging showed infarction/ischemia in the absence of a recognized cerebrovascular accident in 13% of patients. The prevalence of these lesions did not increase significantly between the ages of 6 and 14 years, suggesting that lesions are present by age 6. However, the increase in the average number of lesions per patient with age may indicate progressive brain injury.     

颅脑创伤后植物状态磁共振影像36例分析

目的:研究颅脑创伤后持续植物状态(PAS)的磁共振影像(MRI)特征。方法:分析36例颅脑创伤后持续植物状态患者MRI资料,按病灶位置、性质大小进行统计处理。结果:所有患者都有脑实质损害,共发现脑软化灶312处,平均每例8.67处,主要分布在大脑皮层、脑室旁白质、基底节、脐肌体、脑干。结论:MRI检查对颅脑创伤后持续植物状态的诊治有重要意义。     

MR line-scan diffusion-weighted imaging of term neonates with perinatal brain ischemia.

BACKGROUND AND PURPOSE: MR diffusion-weighted imaging provides early demonstration of neonatal brain infarction. The evolution and limitations of diffusion-weighted imaging findings in newborns, however, have not been evaluated. Using line-scan diffusion imaging (LSDI), we investigated perinatal ischemic brain injury. METHODS: Nineteen term newborns (age, 9 hours to 8 days; mean age, 2.6 days) with perinatal brain ischemia were evaluated using LSDI (1520/62.5/1 [TR/TE/excitations]) (b maximum = 750 s/mm2) and T1- and T2-weighted spin-echo (conventional) MR imaging. Follow-up examinations were performed in seven patients and autopsy in one. Apparent diffusion coefficients (ADCs) were measured in deep gray matter, white matter, the cortex, and focal lesions. RESULTS: Based on conventional MR imaging or pathologic findings, patients were divided into two groups. Group 1 (n = 12) had symmetric/diffuse injury consistent with global hypoperfusion. Group 2 (n = 7) had focal/multifocal injury suggesting cerebrovascular occlusion. ADCs were abnormal at initial examination in 10 newborns in group 1 and in all newborns in group 2. The results of LSDI were abnormal before conventional MR imaging was performed in three newborns in group 1. ADCs were maximally decreased between days 1 and 3 in deep gray matter, perirolandic white matter, and focal lesions. Delayed decreases in ADCs were observed in subcortical white matter from days 4 through 10 in three patients in group 1. CONCLUSION: After global hypoperfusion, LSDI showed deep gray matter and perirolandic white matter lesions before conventional MR imaging. LSDI may underestimate the extent of injury, however, possibly because of variations in the compartmentalization of edema, selective vulnerability, and delayed cell death. Differences in LSDI of symmetric/diffuse and focal/multifocal lesions may reflect differences in pathophysiology or timing of the injury. These findings may have implications for acute interventions.     

Multimodality imaging of cortical and white matter abnormalities in Sturge-Weber syndrome

BACKGROUND AND PURPOSE: Impaired cortical venous outflow and abnormal deep venous collaterals are common in Sturge-Weber syndrome (SWS), but their relation to brain metabolism and function is poorly understood. In this study, advanced MR imaging techniques, such as susceptibility-weighted imaging (SWI) and diffusion tensor imaging (DTI), were applied in conjunction with positron-emission tomography (PET), to assess cortical and white matter structural abnormalities and their relation to cortical glucose metabolism and cognitive functions in children with unilateral SWS. MATERIALS AND METHODS: Thirteen children (age, 1.5-10.3 years) with unilateral SWS underwent MR imaging with SWI and DTI, glucose metabolism PET, and comprehensive neuropsychologic assessment prospectively. The MR imaging and PET images were coregistered and cortical regions showing decreased glucose metabolism were compared with locations of SWI signal intensity abnormalities, changes in white matter water diffusion, and cognitive functions. RESULTS: SWI detected both cortical abnormalities (n=8) and deep transmedullary veins (n=9), including those in young children with no cortical SWI signal intensity changes. These veins were often located under cortex adjacent to hypometabolic regions. DTI showed abnormal water diffusion both under hypometabolic cortex and in adjacent white matter with collateral veins. Cognitive dysfunction was associated with abnormal water diffusion in the posterior white matter. CONCLUSIONS: Transmedullary venous collaterals can be detected early by SWI and persist in white matter adjacent to damaged cortex in children with SWS. Microstructural white matter damage extends beyond cortical abnormalities and may contribute to cognitive impairment. SWI and DTI can be incorporated into clinical MR imaging acquisitions to objectively assess microstructural abnormalities at different stages of SWS.     

Diffusion-weighted imaging of acute corticospinal tract injury preceding Wallerian degeneration in the maturing human brain

BACKGROUND AND PURPOSE: Wallerian degeneration, the secondary degeneration of axons from cortical and subcortical injury, is associated with poor neurologic outcome. Since diffusion-weighted (DW) imaging is sensitive to early changes of cytotoxic edema, DW imaging may depict the acute injury to descending white matter tracts that precedes Wallerian degeneration; this injury is not visible on conventional CT or MR images in the maturing human brain. METHODS: Two neuroradiologists retrospectively analyzed clinical MR images in six children (aged 3 days to 5 months) with DW findings consistent with acute injury of the descending white matter tract due to territorial anterior or middle cerebral artery infarction. In five patients, images were obtained as a part of routine clinical evaluation. The remaining patient was a part of a prospective study of brain injury. Imaging findings were correlated with clinical outcomes. RESULTS: In all six patients, DW imaging performed 2-8 days after the onset of ischemia depicted injury to the descending white matter tract ipsilateral to the territorial infarct. Conventional MR images of the ipsilateral descending white matter tracts were abnormal in three patients. In all five patients for which follow-up results were available, the presence of DW changes was correlated with persistent neurologic disability. CONCLUSION: As shown in this retrospective analysis, DW imaging can depict acute injury to the descending white matter tract in neonates and infants, when conventional MR imaging may show normal findings. These DW findings likely precede the development of Wallerian degeneration, and they may portend a poor clinical outcome.