3T高场强功能MRI在脑功能区胶质瘤皮质电刺激手术中的应用

目的研究应用3T高场强功能MRI（fMRI）定位脑运动功能区，及在脑胶质瘤直接皮质电刺激手术中的指导作用。方法26例邻近或累及脑运动功能区的胶质瘤患者术前采用双手握拳刺激策略，根据血氧水平依赖（BOLD）原理进行功能成像。经工作站提供的BOLD功能图像分析软件包进行分析，获得脑运动功能区的激活图像，制定手术方案。所有患者均在唤醒麻醉下进行显微外科手术，在术前fMRI指导下利用直接皮质电刺激定位运动区。在保护脑功能不受损的前提下，最大程度地切除胶质瘤。术前、术后均行Karnofsky生活状态（KPS）评分，判断患者的状态。结果26例术前BOLD运动fMRI有23例获得良好的手运动脑功能区激活图像。患者在唤醒麻醉下，在术前fMRI指导下利用直接皮质电刺激快捷、准确定位初级运动皮质区，并且两者具有良好的一致性。同时术前fMRI提供术中未检测到的脑功能区的信息，相互补充。术前KPS评分80．0～90．0分患者21例（平均85．7分）术后恢复至平均95．2分，术前KPS评分40．0～70．0分患者5例（平均68．0分）术后恢复至平均90．0分。结论术前fMRI可活体和无创地描绘出脑运动功能区与肿瘤的功能解剖位置关系，优化手术方案，在唤醒麻醉下指导直接皮质电刺激定位运动区的手术，实现最大程度保护脑功能，并最大程度地切除肿瘤。     

电针诱发人脑活动的功能磁共振比较实验研究

目的 探讨电针特异性和穴位特异性脑活动.方法 采用组块刺激模式,电针健康右利手志愿者的右侧合谷穴(9例)、阴陵泉(6例)和面部非穴位点(5例),对全脑行平面回波血氧水平依赖功能磁共振成像(BOLD fMRI)扫描和高分辨率三维T1解剖像,用SPM2软件进行统计学预处理,然后将统计参数图叠加到三维解剖图像.结果 电针可诱发多个脑区信号升高和降低;3组的共同激活区主要包括:双侧前额叶、双侧颞上回和双侧楔前叶;合谷组穴位特异性激活区包括:边缘系统、中线核群、扣带回嘴侧、对侧运动前回和双侧运动前区.结论 电针灸脑反应可分为2部分:穴位特异性和电针特异性反应.     

运动皮层的功能磁共振成像研究

目的　用MR血氧水平依赖性成像技术 (BOLD)研究正常人及癫痫、脑肿瘤患者对指运动皮层的功能磁共振成像 (fMRI)。方法　 3 4例受试者 ,其中 8例正常志愿者 ,2 0例癫痫患者 ,6例脑肿瘤患者 ,行右手、左手对指运动共 43次 ,采用BOLD技术进行相应脑功能区成像。结果　所有受试者均能在MR脑功能检查中表现出局部脑功能活动区规律的信号时间变化曲线 ,并得以清晰成像。功能区附近的占位病变可造成局部功能区的移位和缩小等改变 ,原发性癫痫患者未见有对指运动功能区的明显改变。结论　BOLD -fMRI在活体人脑对指运动的功能区定位方面是一个有效的方法。对需实施手术的颅内占位病变进行BOLD -fMRI检查对指导手术有价值。需改进癫痫患者的脑功能研究 ,进行更有效的相关功能刺激     

功能磁共振成像在脑室旁白质软化症中的应用

通过对24例脑审旁白质软化症(PVL)患儿进行事件相关功能磁共振成像(ER-fMRI)研究,评价fMRI在缺氧缺血性脑损伤后枕叶视觉区功能变化方面的应用价值.选取24例临床确诊为脑瘫的PVL患儿,同时选择无窒息史的健康儿童志愿者12例进行对照研究.对这两组儿童进行fMRI检查,fMRI数据采用SPM2软件进行后处理(ROI),计算患儿与对照组的激活像素数目、HRF曲线幅度以及反应延迟时间,进行配对t检验.正常对照组的激活区位于原始视觉区,BOLD信号变化均为负值,在24例PVL患儿中,枕叶平均激活像素数目减少,4例在PVC区没有激活,6例激活区体积明显减小,7例激活区易位,另有3例激活区明显减小并易位,且HRF曲线郁存在不同程度的反应延迟.fMRI在评价缺氧缺血性脑损伤后视觉功能变化方面有较高的应用价值.     

中央区良性占位病变手术前后手运动及感觉功能区的fMRI研究

目的 探讨中央区良性占位病变患者手术前后手运动及感觉功能区功能磁共振成像(fMRI)的变化特征及临床价值.资料与方法 对位于或邻近脑中央区的17例良性占位病变患者手术前后1周行fMRI检查,刺激方式为对指运动及触刷,共3个周期.经SPM软件处理得出激活图和感兴趣区激活体积.结果 术前功能区主要表现为移位变形,激活区体积缩小.术后1周内复查,功能区移位有所恢复,功能区激活体积无明显改变(P＞0.05).结论 中央区良性占位病变周围功能区手术前后主要产生体积、形态及解剖位置的改变.术后1周功能区体积变化不明显.     

PET图像与CT、MRI图像比较与融合的研究

目的 将PET的功能代谢图像与CT、MRI的解剖图像进行比较与融合。方法 21例癫痫患者和53例肿瘤或疑为肿瘤患进行了PET检查。患者的CT、MRI资料通过扫描仪输入计算机。在融合软件“MPItool”中,通过调整PET的三维容积图像,找到与二维CT、MRI断面图像对应的层面进行比较与融合。结果 29个代谢改变病灶被准确定位于21例癫痫患者相应的MRI图像上。PET显示53个肿瘤阳性病灶亦定位于相应的CT或MRI图像上,其中10个病灶在CT、MRI报告中忽略。CT、MRI检测到的另外23个病灶PET显像没有摄取或摄取不高,最终都被证明为良性病变。结论 图像的比较与融合有助于更全面地了解病变的性质及周围解剖结构的关系。采用的融合方法简单、实用,临床可行。     

健康儿童记忆的fMRI及其信号机制的基础研究

目的 运用功能磁共振成像(fMRI)研究健康儿童志愿者记忆抽象图片时的脑内活动区情况,并研究其信号产生的机制.方法 以15名健康儿童志愿者作为研究对象,运用单次激发GRE-EPI扫描采集fMRI图像,分别以抽象图片的记忆和提取作为编码刺激和提取刺激.用SPM软件对fMRI图像和T1WI解剖图像进行融合,并对脑内活动区进行分析.结果 编码和提取刺激的脑区主要在双侧海马区(左侧显著)、双侧前额叶、双侧枕叶及顶叶,但各激活脑区的激活较弱.结论 儿童记忆激活的脑区较广,但其强度较弱,这可能与儿童记忆能力尚处在发育阶段有关.     

脑电联合同步功能MRI在局灶性癫痫检测中的应用价值

目的探讨脑电监测模式的脑电同步功能MR成像（EEG-fMRI）技术在局灶性癫痫患者间期痫样放电引起的脑区激活情况的应用价值。方法对12例局灶性癫痫患者进行EEG-fMRI数据采集；以间期痫样放电的事件相关设计模式对fMRI数据进行分析，观察癫痫放电引起脑激活的时空分布情况。并与MR结构成像病灶定位结果进行对比。结果12例患者中，共采集到10例患者的18次有效EEG-fMRI数据。与结构病灶相对比，11次数据显示定位结果较好，5次结果尚可，2次结果不佳；其中6例患者2次采集的定位结果相同。18次扫描结果均显示激活大脑对侧的小脑有稳定的激活；10次结果中丘脑有正激活信号，9次有位于典型的缺省状态分布脑区的负激活信号。结论EEG-fMRI技术利用多模态神经成像技术的优点，在癫痫的研究方面有较大的应用价值。     

步进式视觉累加实验(PVSAT)功能磁共振研究

目的:利用功能磁共振成像(fMRI)技术探讨步进式视觉累加实验(PVSAT)在人脑的作用部位及其意义.方法:12例健康志愿者完成以步进式视觉累加实验(PVSAT)作为刺激模式(包括计算、工作记忆和注意力几个方面的认知功能模式)、采用组块设计(block)的fMRI检查,经SPM2软件处理获得脑功能图像.结果:PVSAT试验中健康志愿者的双侧顶上小叶区、顶下小叶区及额上回、额中回可见激活,而优势半球(左侧)较对侧激活区稍大、强度稍高;左侧额下回和扣带回可见激活;双侧枕叶视觉皮层区有明显激活;小脑亦可见少量激活.结论:PVSAT脑内激活区主要在额顶叶,fMRI可显示脑内激活区,对脑功能的深入研究有重要价值.     

被动手运动fMRI在中央区胶质瘤患者术前定位有效性的应用研究

目的 探讨基于血氧水平依赖(BOLD)功能磁共振成像(fMRI)的被动手运动刺激对中央区胶质瘤运动功能区术前定位的有效性.方法 选取病灶位于中央区的胶质瘤患者15例,分别对患者进行主动手运动及被动手运动的任务刺激,采用独立成分分析方法观察运动功能区的激活范围及强度的变化.结果 被动手运动与主动手运动fMRI激活范围及强...     

脑功能磁共振信号的时间聚类分析

目的:探讨功能磁共振信号的主要组成及运动伪影对其影响。方法:采用自编程序实现时间聚类分析算法对2例事件相关模式视觉刺激任务的功能磁共振数据进行分析,并与(statistical parametric mapping,SPM)拟合曲线图及实验时间序列中运动轨迹记录做比较分析。结果:时间聚类分析在血氧水平反应阈值范围内可检测到大量反应信号,通过与SPM拟合调整曲线图比较发现,BOLD事件反应时,与时间聚类分析(TCA)结果可发现与其重叠的信号;通过与时间序列中运动轨迹记录进行比较发现,TCA所检出较大的信号均与运动波峰有很大程度的相关。结论:时间聚类分析作为一种数据驱动的功能磁共振数据分析方法,一定程度上可以反映真正的血氧水平,但受运动伪影影响严重,在类短时程刺激的事件相关模式的功能成像实验时可谨慎使用。     

Comparison of TCA and ICA techniques in fMRI data processing

PURPOSE: To make a quantitative comparison of temporal cluster analysis (TCA) and independent component analysis (ICA) techniques in detecting brain activation by using simulated data and in vivo event-related functional MRI (fMRI) experiments. MATERIALS AND METHODS: A single-slice MRI image was replicated 150 times to simulate an fMRI time series. An event-related brain activation pattern with five different levels of intensity and Gaussian noise was superimposed on these images. Maximum contrast-to-noise ratio (CNR) of the signal change ranged from 1.0 to 2.0 by 0.25 increments. In vivo visual stimulation fMRI experiments were performed on a 1.9 T magnet. Six human volunteers participated in this study. All imaging data were analyzed using both TCA and ICA methods. RESULTS: Both simulated and in vivo data have shown that no statistically significant difference exists in the activation areas detected by both ICA and TCA techniques when CNR of fMRI signal is larger than 1.75. CONCLUSION: TCA and ICA techniques are comparable in generating functional brain maps in event-related fMRI experiments. Although ICA has richer features in exploring the spatial and temporal information of the functional images, the TCA method has advantages in its computational efficiency, repeatability, and readiness to average data from group subjects     

Hidden Markov event sequence models: toward unsupervised functional MRI brain mapping

RATIONALE AND OBJECTIVES: Most methods used in functional MRI (fMRI) brain mapping require restrictive assumptions about the shape and timing of the fMRI signal in activated voxels. Consequently, fMRI data may be partially and misleadingly characterized, leading to suboptimal or invalid inference. To limit these assumptions and to capture the broad range of possible activation patterns, a novel statistical fMRI brain mapping method is proposed. It relies on hidden semi-Markov event sequence models (HSMESMs), a special class of hidden Markov models (HMMs) dedicated to the modeling and analysis of event-based random processes. MATERIALS AND METHODS: Activation detection is formulated in terms of time coupling between (1) the observed sequence of hemodynamic response onset (HRO) events detected in the voxel's fMRI signal and (2) the "hidden" sequence of task-induced neural activation onset (NAO) events underlying the HROs. Both event sequences are modeled within a single HSMESM. The resulting brain activation model is trained to automatically detect neural activity embedded in the input fMRI data set under analysis. The data sets considered in this article are threefold: synthetic epoch-related, real epoch-related (auditory lexical processing task), and real event-related (oddball detection task) fMRI data sets. RESULTS: Synthetic data: Activation detection results demonstrate the superiority of the HSMESM mapping method with respect to a standard implementation of the statistical parametric mapping (SPM) approach. They are also very close, sometimes equivalent, to those obtained with an "ideal" implementation of SPM in which the activation patterns synthesized are reused for analysis. The HSMESM method appears clearly insensitive to timing variations of the hemodynamic response and exhibits low sensitivity to fluctuations of its shape (unsustained activation during task). Real epoch-related data: HSMESM activation detection results compete with those obtained with SPM, without requiring any prior definition of the expected activation patterns thanks to the unsupervised character of the HSMESM mapping approach. Along with activation maps, the method offers a wide range of additional fMRI analysis functionalities, including activation lag mapping, activation mode visualization, and hemodynamic response function analysis. Real event-related data: Activation detection results confirm and validate the overall strategy that consists in focusing the analysis on the transients, time-localized events that are the HROs. CONCLUSION: All the experiments performed on synthetic and real fMRI data demonstrate the relevance of HSMESMs in fMRI brain mapping. In particular, the statistical character of these models, along with their learning and generalizing abilities are of particular interest when dealing with strong variabilities of the active fMRI signal across time, space, experiments, and subjects.     

Improved temporal clustering analysis method for detecting multiple response peaks in fMRI

PURPOSE: To develop an improved temporal clustering analysis (TCA) method for detecting multiple active peaks by running the method once. MATERIALS AND METHODS: Two cases of simulation data and a set of actual fMRI data from nine subjects were used to compare the traditional TCA method with the new method, termed extremum TCA (ETCA). The first case of simulation data simulated event-related activation and block activation in one cerebral area, and the second case simulated event-related activation and block activation in two cerebral areas. An in vivo visual stimulating experiment was performed on a 1.5T MR scanner. All imaging data were processed using both traditional TCA and the new method. RESULTS: The results of both the simulated and actual fMRI data show that the new method is more sensitive and exact than traditional TCA in detecting multiple response peaks. CONCLUSION: The new method is effective in detecting multiple activations even when the timing and location of the brain activation are completely unknown.     

肝硬化患者工作记忆任务的fMRI研究

目的：通过n-back语义工作记忆任务的功能磁共振成像（~MRI）技术探讨肝硬化患者语义工作记忆损伤的神经病理学机制。方法：对10例轻微肝性脑病（MHE组）、14例单纯肝硬化（non-HE组）患者及16例正常对照者（对照组）行n-back语义工作记忆任务的fMRI研究。n-back实验采用组块设计,对照状态为0-back,任务状态为1-back和2-back。采用基于MATLAB的SPM8软件对数据进行处理分析。采用单样本t检验分析三组受试者在两种任务状态下的大脑激活情况,采用单因素方差分析观察三组受试者两种任务状态（1和2-back）下脑区激活的差异,采用Pearson相关分析行工作记忆任务脑激活区与任务执行正确率及反应时间之间的相关性。结果：在n-back任务中,三组受试者均表现为额顶叶脑网络的激活,包括双侧前额叶、双侧顶叶、双侧前运动区以及辅助运动区。在1-back任务下,non-HE组及MHE组主要表现为工作记忆部分脑区激活的增加;在2-back任务下,non-HE组及MHE组表现为工作记忆相关脑区激活的减低。肝硬化患者左侧额中回激活与2-back任务执行正确率密切相关。结论：肝硬化患者存在语义工作记忆相关脑区的损害。1-back任务时主要表现为脑区的代偿,但MHE较单纯肝硬化代偿能力减低;2-back任务难度超出代偿限度,主要表现为激活下降,且MHE较单纯肝硬化损伤更明显。     

Effects of Head Motion on the Evaluation of Age-related Brain Network Changes Using Resting State Functional MRI

Purpose:The estimation of functional connectivity (FC) measures using resting state functional MRI (fMRI) is often affected by head motion during functional imaging scans. Head motion is more common in the elderly than in young participants and could therefore affect the evaluation of age-related changes in brain networks. Thus, this study aimed to investigate the influence of head motion in FC estimation when evaluating age-related changes in brain networks.Methods:This study involved 132 healthy volunteers divided into 3 groups: elderly participants with high motion (OldHM, mean age (±SD) = 69.6 (±5.31), N = 44), elderly participants with low motion (OldLM, mean age (±SD) = 68.7 (±4.59), N = 43), and young adult participants with low motion (YugLM, mean age (±SD) = 27.6 (±5.26), N = 45). Head motion was quantified using the mean of the framewise displacement of resting state fMRI data. After preprocessing all resting state fMRI datasets, several resting state networks (RSNs) were extracted using independent component analysis (ICA). In addition, several network metrics were also calculated using network analysis. These FC measures were then compared among the 3 groups.Results:In ICA, the number of voxels with significant differences in RSNs was higher in YugLM vs. OldLM comparison than in YugLM vs. OldHM. In network analysis, all network metrics showed significant (P < 0.05) differences in comparisons involving low vs. high motion groups (OldHM vs. OldLM and OldHM vs. YugLM). However, there was no significant (P > 0.05) difference in the comparison involving the low motion groups (OldLM vs. YugLM).Conclusion:Our findings showed that head motion during functional imaging could significantly affect the evaluation of age-related brain network changes using resting state fMRI data.     

血氧水平依赖功能磁共振成像在累及运动区脑肿瘤中的应用

目的：功能磁共振成像对脑肿瘤术前评估具有重要意义,探讨血氧水平依赖功能磁共振成像（Bold-fMRI）在累及运动通路脑肿瘤中的应用价值。方法：对16例累及皮层运动区的脑肿瘤患者行fMRI检查,另以10例健康者作为对照,2例患者术后复查,fMRI采用双侧交替进行的大拇指对掌运动作为任务刺激。所有数据进行离线后处理,fMRI图像使用基于MATLAB平台下运行的SPM99软件进行处理,观察运动皮层区激活情况。结果：每个患者的健、患侧主运动区（M1）、辅助运动区（SMA）均激活,其中12例患侧M1区信号低于健侧,3例患侧M1区信号高于健侧,1例健侧与患侧M1区信号无明显差别,11例患侧M1区信号移位,8例患者患侧SMA区及健侧M1区的激活程度较健康人增强;2例患者复查显示患侧M1皮层激活范围较术前变小。结论：应用fMRI能显示肿瘤、皮层运动功能区之间的关系,对邻近脑运动功能区脑肿瘤患者术前评估具有重要意义。     

正常人工作记忆任务和静息状态下前额叶皮层内侧面的功能连接分析

目的 分析在工作记忆任务和静息两种状态下与前额叶皮层内侧面(MPFC)正、负相关脑区的分布,比较两种状态下MPFC功能连接的差异.资料与方法 采用GE 1.5 T MR扫描仪对25名正常自愿者行静息态及2-back工作记忆任务的功能磁共振成像(fMRI)实验,2-back实验采用组块设计,0-back作为对照,6个对照组块与5个任务组块交替进行.静息态全脑采集128个时相.采用SPM、AFNI对数据进行预处理.选择MPFC作为种子点与全脑其他像素进行Pearson相关分析,建立相关图.组内分析时采用随机效应模型单样本t检验,检测与MPFC明显正相关或负相关的脑区.组间分析采用配对样本t检验.检测MPFC功能连接图在2-back任务和静息状态下的差异.结果 两种状态下与MPFC正相关的脑区基本一致,属于"任务负激活网络".2-back任务状态下与MPFC负相关的脑区与"任务正激活网络"一致.静息状态下与MPFC负相关的脑区主要分布在双侧岛叶、双侧顶下小叶,且这些区域的负相关性明显高于任务状态.任务状态下负相关性高于静息状态的主要脑区包括双侧运动前区外侧(LPMA)、双侧顶叶后部(PPC)、左侧丘脑及右侧小脑半球.结论 静息及2-back任务状态下MPFC的功能连接情况不同,对于正常人在静息及任务状态下的功能连接对比研究为临床精神疾病患者的研究奠定了基础.     

听觉性语言刺激的功能磁共振成像研究

目的用MR血氧水平依赖性(BOLD)技术研究听觉语言的功能磁共振成像(fMRI)。资料与方法23例受试者，其中正常志愿者14例，脑肿瘤患者6例，脑外伤软化灶形成患者3例。进行听觉性语言刺激共25次，采用BOLD技术进行相应脑功能区成像。结果所有受试者均能在MRI检查中表现出局部脑功能活动区规律的信号强度-时间变化曲线，并获得较清晰的图像。功能区附近的占位病变可造成局部功能区的移位和缩小等改变。结论BOLD-fMRI在活体人脑听觉语言的功能区定位方面是一种有效的方法。对需实施手术的颅内占位。病变进行BOLD-MRI检查对指导手术有价值。     

Functional MRI of the brain: localisation of eloquent cortex in focal brain lesion therapy

The aim of this study was to assess the feasibility of functional MRI (fMRI) in a clinical environment on a large patient group, and to evaluate the pretherapeutic value of localisation of eloquent cortex. Forty patients with focal brain lesions of different origin were studied using fMRI. Functional information was obtained using motor, somatosensory, auditory and phonological stimuli depending on the localisation of the lesions. To obtain information about the spatial accuracy of fMRI, the results were compared with postoperative electrocortical stimulation. Two patients with secondary trigeminal neuralgia were scanned using a motor protocol and were implanted with an extradural plate electrode. Imaging was successful in 40 of 42 patients (including the 2 with trigeminal neuralgia). These patients were analysed for strength of activation, the relation of the lesion to activation sites and the presence of mass effect. The correlation between these data and surgical findings provided significant additional clinical information. Functional MRI can be accurately performed in patients with focal brain lesions using a dedicated approach. Functional MRI offers important clinical information as a contribution to a decrease in posttherapeutic morbidity. The accuracy of the technique can be confirmed by other modalities, including invasive cortical electrostimulation. Received 19 November 1997; Revision received 23 February 1998; Accepted 3 March 1998