锥体束Wallerian变性的MRI诊断

目的探讨MRI在诊断脑损害后锥体束Wallerian变性中的应用。方法对22例脑损害后锥体束Walle-rian变性患者均行MRI检查。常规行快自旋回波序列(FSE)横断位T1WI(TR 2 286ms,TE 19.6ms)、T2WI(TR4 300ms,TE 113ms)和T2Flair序列(TR 8 502ms,TE 133ms)。视野(FOV)24cm,矩阵320×256,激发次数(NEX)1～2,层厚6mm,层间距1mm,层数21层。22例患者均加扫横轴位DWI(b值为1 000s.mm-2),其中10例另加扫3D-TOF-MRA(TR 26ms,TE 6.8ms)检查。结果 22例患者中,12例患者在脑损害≥4周～≤12个月后行常规MRI检查,主要表现为病变同侧的锥体束呈长T1、长T2信号并同侧大脑脚及桥脑体积稍萎缩;2例患者在脑损害<4周行常规MRI检查,主要表现为病变侧锥体束稍长T1、长T2信号;8例患者在脑损害>1年行常规MRI检查,主要表现为原发病灶、大脑脚及桥脑萎缩并T2Flair像呈现散在斑片稍高信号影。结论 MRI可明确显示脑损害后锥体束Wallerian变性,有助于临床医师对患者运动功能康复的治疗。     

肥大性下橄榄核变性的临床和影像学特点分析

目的探讨继发性肥大性下橄榄核变性(hypertrophic olivary degeneration,HOD)的临床及影像学特点。方法回顾性分析脑干出血后继发性HOD 1例的临床资料。结果本例6个月前患脑干出血,治疗后遗留饮水呛咳、言语不清、头晕、左侧肢体无力症状。此次因头晕伴左侧肢体麻木、无力加重15 d入院,查体示眼球震颤、共济失调、复视、饮水呛咳、震颤及肌张力增高等多颅神经损害及锥体外系症状;头颅MRI检查示水平位延髓腹侧等T1、长T2信号及延髓下橄榄核区局限性肥大。诊断为继发性HOD,予氯丙嗪及美多巴等治疗后症状逐渐减轻,病情好转出院。结论继发性HOD以多颅神经损害症状为主,脑MRI检查可见下橄榄核区异常信号和局限性肥大,对鉴别诊断有重要意义。     

基底节区脑出血后相关神经纤维继发性损害的磁共振研究

目的:探讨应用磁共振弥散张量成像(DTI)技术动态观察基底节区脑出血后神经纤维的顺行性、逆行性变性的过程。方法:选取2011年1月-2012年6月收治的单侧基底节区出血病灶患者10例为研究组,分别在发病的第1周、1月、3月进行DTI检测,得到半卵圆中心、放射冠、内囊、大脑脚、脑桥等部位的部分各向异性图(FA)并测量其值,并与正常对照组10例比较。结果:在出血灶同侧近端纤维束行程上和远端锥体束经路上都可出现清晰可见的信号减弱区,从发病的第1周至3月FA值明显降低。结论:基底节区脑出血除了原发部位的损伤,还可以出现其近端、远端纤维的继发性变性改变。     

多层螺旋CT及低场MRI在脑部华勒变性诊断中的应用

目的分析锥体束华勒变性多层螺旋CT及低场MRI影像特点,提高诊断水平。方法回顾性分析33例经临床及影像诊断的脑部华勒变性患者的临床及影像资料,根据病程分期,按CT、MRI分组进行对比。结果脑部华勒变性最常见于皮质脊髓束及皮质核束走行区,在原发病灶基础上,多层螺旋CT表现为远离原发病灶之锥体束区密度减低影,低场MRI表现为长T1、长T2信号,晚期患者出现病侧大脑脚、丘脑、基底节及半卵圆中心的萎缩。33例病例中,多层螺旋CT显示23例,一期2例,二期3例,三期10例,四期8例。低场MRI显示33例,一期4例,二期5例、三期16例、四期8例。其中低场MRI对早期(一~三期)华勒变性的诊断率优于CT。结论锥体束华勒变性具有一定的影像特征,多层螺旋CT及低场MRI对其诊断具有较高价值。     

脑硬膜下血肿的Kernohan-Woltman现象及同侧颞叶脑软化

急性颅脑损伤后，通常只注意脑损伤对侧肢体的运动障碍。但是，应引起注意的是在急性脑硬膜下血肿术后，出现同侧肢体运动瘫痪。同侧肢体瘫痪首先由Ｋｅｒｎｏｈａｎ和Ｗｏｌｔｍａｎ报道，由于对侧大脑脚受压后引起大脑脚综合征。这一现象首先出现在原发性脑肿瘤患者，罕...     

丁基苯酞对脑梗死灶远隔部位继发性损害的影响

目的:采用磁共振弥散张量成像(DTI)探讨丁基苯酞治疗对脑梗死患者梗死灶远隔部位继发性损害的影响。方法:60例急性脑梗死患者随机分为丁基苯酞组和对照组各30例。2组均给予抗血小板及基础治疗,丁基苯酞组加用丁基苯酞,于治疗前及治疗4周后行美国国立卫生研究院卒中量表(NIHSS)、改良Rankin评分(mRS)及DTI扫描,分别测量梗死灶、梗死同侧大脑脚及对侧相应区域的部分各向异性(FA)值。结果:治疗4周后,2组患者NIHSS和mRS评分均较治疗前降低(P<0.01),丁基苯酞组低于对照组(P<0.05);2组患者梗死灶及同侧大脑脚水平锥体束的FA值均较治疗前下降(P<0.01),丁基苯酞组的梗死灶、同侧大脑脚FA值均大于对照组(P<0.01)。结论:丁基苯酞可能通过减轻梗死后远隔损害而改善脑梗死患者的神经功能损害。     

肝豆状核变性脑CT和MRI诊断

目的分析肝豆状核变性（HLD）的脑CT和MRI征象，进一步提高对HLD病认识及诊断的正确率。方法对临床和生化检查证实36例HLD的脑CT和MRI征象及临床表现进行回顾性分析。结果CT检查26例中主要表现为对称性基底节区低密度影。30例MRI呈对称性条状或新月形长T1长T2信号，FIR高信号、或稍短T1短T2信号，典型者依受累部位不同分别为啄木鸟、八字，展翅蝴蝶样改变等，其中病灶位于壳核30例，尾状核16例，丘脑15例，苍白球、红核各3例。黑质、大脑脚网状结构、脑桥桥核、额叶白质各2例，15例有轻度或重度脑萎缩。结论HLD脑CT及MRI最常见征象是基底节区低密度影或异常信号和不同程度脑萎缩，以双侧豆状核区对称性低密度或异常信号最具特征性。     

高血糖致中枢神经系统影像学改变2例分析及文献复习

目的探讨高血糖致脑基底节区影像学改变的临床表现、疗效及其病理生理机制。方法选择2例典型患者进行临床表现、治疗经过及影像学改变的回顾性分析,并学习相关文献。结果 2例糖尿病患者,1例为非酮症高血糖,1例为酮症高血糖,临床表现不同,1例表现为偏侧舞蹈症,1例表现为肢体抽搐、偏侧肢体运动障碍。影像学改变有特征性,早期CT表现为对侧纹状体高密度影,MRI表现为病灶区T1高信号,T2等信号,边界清晰,无水肿征象。结论高血糖致中枢神经系统影像学改变最常见的临床表现为偏侧舞蹈症,发病部位以纹状体为主,CT早期表现为高密度影,易与脑出血相混淆,MRI异常信号有助于早期诊断,降低误诊率。     

MCAO脑缺血后同侧黑质MRI动态改变

目的：分析线栓法制作单侧大脑中动脉供血区脑缺血后同侧黑质的MR信号变化特点。方法：清洁级健康雄性SD大鼠（270~320g）16只，按照随机分组原则分成两组：永久性大脑中动脉阻塞（MCAO）组12只，假手术对照组4只。应用线栓法制作脑缺血模型，模型制作成功后1h、3h、6h、9h、12h、1d、3d、7d行俯卧位冠状面磁共振扫描。主要序列包括T2WI、T2map，观察脑缺血范围，计算并测量两侧纹状体、皮质和黑质T2值。结果：假手术对照组磁共振图像上双侧纹状体、皮质及黑质等脑组织各部均未出现异常表现。MCAO组大鼠MR扫描显示脑缺血范围累及脑皮质和左侧纹状体及其它皮质下结构，脑缺血区T2信号的动态变化具有一定的时间特征。1h、3h、6h、9h、12h、1d时双侧黑质未见异常MR表现。3d时MCAO组动物均显示脑缺血同侧黑质T2高信号，境界清楚，由T2map测得T2值增高。对侧黑质信号无明显变化，两侧黑质T2值差异有显著意义。7d MCAO组大鼠左侧黑质异常信号消失，双侧黑质T2值未见差异。MCAO后同侧黑质T2值的变化曲线与脑皮质和纹状体T2值的变化不同步。结论：线栓法制作单侧大脑中动脉阻塞脑缺血后3d同侧黑质出现MR异常信号。     

脑瘤块样脱髓鞘病变1例

患者女,40岁.左上下肢麻木、无力2周,同时伴枕后痛.发病前1周曾有发热史,口服解热镇痛药物缓解.查体:左侧上下肢体肌力Ⅲ级,肌张力正常,病理征阴性.实验室检查未见明显异常.MRI表现:右侧额叶团块状异常信号影,T2WI呈高信号,T1WI为稍低信号,FLAIR为高信号(图1～3),病灶信号较均匀,边界清,灶周未见明显水肿影,无明显占位效应.Gd-DTPA增强扫描,病灶呈非闭合性环状强化(图4).临床拟诊为瘤块样脱髓鞘病变,给予激素冲击治疗,20 d后患者自觉症状减轻.复查MRI,右额叶病灶较前缩小,病灶T1WI信号较前明显减低,其间见斑点状高信号影(图5).     

Extent of pyramidal tract wallerian degeneration in the brain stem on MRI and degree of motor impairment after supratentorial stroke.

The relationship between Wallerian degeneration in the brain stem and degree of motor impairment is discussed. Using MRI we studied 172 supratentorial stroke patients, whose motor impairment was graded according to Brunnstrom stage. Wallerian degeneration was represented by a T2 high-intensity area in the brain stem, and its cross-sectional extent was measured at the cerebral peduncle level. Wallerian degeneration was detected in 99 patients (57.6%). The area of T2 high intensity was significantly correlated with Brunnstrom stage. Multiple regression analysis showed that the upper extremity stage contributed most to the visualization of Wallerian degeneration. This is partly because the pyramidal tract participates in fine and precise movement. The extent of the area of Wallerian degeneration is found to be helpful in making a prognosis with respect to motor impairment in the upper extremity.     

基于DTI的脊髓型颈椎病患者皮质脊髓束逆行性损害的研究

目的:应用磁共振弥散张量成像(DTI)观察脊髓型颈椎病(CSM)患者皮质脊髓束(CST)逆行性Wallerian变性的特征,并分析其损伤程度与肢体运动功能障碍的关系。资料与方法:对28例CSM患者及28例性别和年龄相匹配的健康志愿者行常规MRI及DTI检查,分别测量位于双侧脑桥、大脑脚、内囊后肢、侧脑室体旁白质、半卵圆中心及中央前回皮层下白质的ROI的各向异性分数(FA)值和表观扩散系数(ADC)值。所有被试者均采用JOA运动评分法进行临床运动功能评分。研究各ROI的FA值及ADC值的变化,并分析其与临床运动功能评分的相关性。结果:CSM组各ROI左右两侧对称部位的FA、ADC值差异均无统计学意义(P>0.05)。与健康对照组相比,CSM患者的各平面的FA值均减低(P<0.05),半卵圆中心、内囊后肢及脑桥的ADC值升高(P<0.05)。CSM组的JOA评分较对照组减低(P<0.05),且与内囊后肢、大脑脚、脑桥处的FA值以及内囊后肢的ADC值相关。结论:DTI可以检测出CSM患者CST的继发性逆行性Wallerian变性,而且这种逆行性的神经纤维继发性变性可能与患者的运动功能受损有关。     

Diffusion tensor imaging detects early Wallerian degeneration of the pyramidal tract after ischemic stroke

We used diffusion tensor imaging (DTI) to assess Wallerian degeneration of the pyramidal tract within the first 2 weeks after ischemic stroke, and correlated the extent of Wallerian degeneration with the motor deficit. Nine patients with middle cerebral artery stroke were examined 2-16 days after stroke by DTI and T2-weighted MRI. We measured fractional anisotropy (FA), averaged diffusivity (Dav), eigenvalues of the diffusion tensor and T2-weighted signal in the cerebral peduncle and compared these values between the affected and the unaffected side and between patients and six controls. FA was significantly reduced on the affected side compared to the unaffected side and compared to the control group. The largest eigenvalue was reduced, whereas the smallest eigenvalue was elevated on the affected side. There was no significant difference in T2-weighted signal and Dav. The decrease of anisotropy correlated positively with the motor deficit at the time of DTI study and 90 days after stroke. The reduction of anisotropy mirrors the disintegration of axonal structures, as it occurs in the early phase of Wallerian degeneration. DTI detects changes of water diffusion related to beginning pyramidal tract degeneration within the first 2 weeks after stroke that are not yet visible in conventional T2-weighted or orientationally averaged diffusion weighted MRI. We demonstrated for the first time a correlation of early DTI findings of pyramidal tract damage with the motor deficit. DTI can help prognosing recovery of motor function after stroke within the early subacute phase.     

脑梗死后锥体束Wallerian变性的DTI研究进展

运动通路缺血性脑卒中可导致病灶远端的锥体束发生Wallerian变性,扩散张量成像技术显示Wallerian变性不仅具有较高的敏感性和特异性,而且能在活体定量监测其演变过程,这对判断脑卒中患者的预后具有重要意义。本文主要针对脑卒中后锥体束Wallerian变性的扩散张量研究进展进行综述。     

Water Diffusion Changes in Wallerian Degeneration and Their Dependence on White Matter Architecture

This study investigates water diffusion changes in Wallerian degeneration. We measured indices derived from the diffusion tensor (DT) and T2-weighted signal intensities in the descending motor pathways of patients with small chronic lacunar infarcts of the posterior limb of the internal capsule on one side. We compared these measurements in the healthy and lesioned sides at different levels in the brainstem caudal to the primary lesion. We found that secondary white matter degeneration is revealed by a large reduction in diffusion anisotropy only in regions where fibers are arranged in isolated bundles of parallel fibers, such as in the cerebral peduncle. In regions where the degenerated pathway crosses other tracts, such as in the rostral pons, paradoxically there is almost no change in diffusion anisotropy, but a significant change in the measured orientation of fibers. The trace of the diffusion tensor is moderately increased in all affected regions. This allows one to differentiate secondary and primary fiber loss where the increase in trace is considerably higher. We show that DT-MRI is more sensitive than T2-weighted MRI in detecting Wallerian degeneration. Significant diffusion abnormalities are observed over the entire trajectory of the affected pathway in each patient. This finding suggests that mapping degenerated pathways noninvasively with DT-MRI is feasible. However, the interpretation of water diffusion data is complex and requires a priori information about anatomy and architecture of the pathway under investigation. In particular, our study shows that in regions where fibers cross, existing DT-MRI-based fiber tractography algorithms may lead to erroneous conclusion about brain connectivity.     

Magnetization transfer measurements of brain structures in patients with multiple system atrophy

To determine whether magnetization transfer imaging (MTI) demonstrates abnormalities in the brain structures of patients with multiple system atrophy (MSA), we examined 12 patients with clinically probable MSA and 11 control subjects. We calculated magnetization transfer ratios (MTRs) using region of interest analysis from MTI and assessed abnormal signal changes on T2-weighted images. MTRs of the base of the pons, middle cerebellar peduncle, putamen, and white matter of the precentral gyrus were significantly lower in the MSA patients than in the controls. Abnormal signal changes on T2-weighted images were observed in the base of the pons (n = 6), middle cerebellar peduncle (n = 7), and putamen (n = 7). MTRs of regions with abnormal signals were significantly lower than those of regions without abnormal signals and those in the controls. Even the MTRs of the regions without abnormal signals were lower than those in the controls. MTRs of the pyramidal tract, including white matter of the precentral gyrus, posterior limb of the internal capsule, cerebral peduncle, and base of the pons, were significantly lower in patients with pyramidal tract sign (n = 7) than in the controls. Patients with asymmetrical parkinsonism (n = 5) showed significantly lower MTRs in the putamen contralateral to the predominant side of parkinsonian symptoms than the ipsilateral side, although asymmetry of abnormal signal changes on T2-weighted images was not evident in more than half of those patients. This study showed that MTI demonstrates abnormalities in the brains of patients with MSA that seem to reflect underlying pathological changes and that the pathological changes detected by MTI seem to give rise to clinical symptoms. This study also showed that the abnormalities are detected more sensitively and over a larger area by MTI than by conventional magnetic resonance imaging.     

定量DTI在儿童脑室周白质损伤所致脑瘫中的应用

【目的】运用扩散张量成像（DTI）技术,评价脑室周脑白质损伤患儿脑白质和深部灰质的扩散特性。【方法】采用配对设计方法,对25例脑室周脑白质损伤患儿和25例正常儿童进行常规MRI和DTI检查。用Functool2和DTIStudio软件处理原始图像,得到DTI图像。分析大脑、脑干不同脑白质区域及丘脑、豆状核、尾状核头部深部灰质核团感兴趣区（ROD的平均扩散率（MD）和部分各向异性值（FA）。采用配对资料t检验统计方法检验患儿组与对照组的MD和FA有无显著性差异。【结果】与对照组相比,怠儿组脑白质损伤病灶的ROI测量显示MD显著升高和FA显著下降,患儿组锥体束内囊后肢层面FA减低具有统计学意义,患儿组深部灰质核团MD和FA差异无统计学意义。【结论】不同区域运动通路的变性,在脑室周脑白质损伤患儿的病理生理学机制中发挥重要作用。     

Pyramidal tract lesions and movement-associated cortical recruitment in patients with MS

Cortical functional changes, with the potential to limit the functional consequences of tissue injury, have been shown in patients with multiple sclerosis (MS). In this study, we assessed the influence of MS-related tissue damage of the brain portion of the left pyramidal tract on the corresponding movement-associated patterns of cortical recruitment in a large sample of MS patients when performing a simple motor task with their fully normal functioning right upper limbs. We investigated 76 right-handed patients with definite MS. In each subject, functional magnetic resonance imaging (fMRI) was acquired during the performance of a simple motor task with the dominant, right upper limb. During the same session, dual-echo, magnetization transfer (MT) and diffusion tensor (DT) MRI sequences were also obtained to quantify the extent and the severity of pyramidal tract damage. Lesions along the left pyramidal tract were identified in 43 patients. Compared to patients without pyramidal tract lesions, patients with such lesions had more significant activations of the contralateral primary sensorimotor cortex (SMC), secondary sensorimotor cortex (SII), inferior central sulcus, and cingulate motor area (CMA). They also showed more significant activations of several regions of the ipsilateral hemisphere, including the primary SMC and the precuneus. In these patients, T2 lesion load of left pyramidal tract was correlated with the extent of activation of the contralateral primary SMC (r2 = 0.25, P < 0.0001), whereas no correlations were found between the extent of fMRI activations and the severity of intrinsic lesion damage, as well as with left pyramidal tract normal-appearing white matter damage. This study shows that, in patients with MS, following injury of the motor pathways, there is an increased recruitment of a widespread sensorimotor network, which is likely to contribute to limit the appearance of overt clinical deficits.