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     

累及大脑皮层运动区的颅内病变手术前后磁共振功能成像

目的：作者利用功能性磁共振成像原理,对颅内病变累及运动皮层的病人进行了术前、术后的成像检查。即对患者进行手指运动功能区的皮层定位检查,分辨这些重要的功能皮层区与病变的相邻关系。方法：３１例需进行手术治疗的病人,采用血氧依赖水平（ＢＯＬＤ）原理进行扫描,并经过计算机后处理获得脑功能区的影像表现。结果：所有的病例均能在脑功能成像检查中表现出局部脑功能活动区（相应的手指运动支配功能区）规律的信号－时间变化曲线。以及由于病变造成的皮层功能区的移位和缩小等形态学改变。结论：在常规的ＭＲ成像后进行功能性ＭＲ成像研究,对需实施颅内占位病变、特别是对有累及运动皮层焦行切除术者有十分重要的临床指导意义。     

人脑视皮质功能MRI的初步研究及临床应用

目的：本实验应用功能磁共振成像（fMRI）的回波平面（EPI）技术,着重研究了人脑视皮质的血氧水平依赖（BOLD）的功能磁共振成像。方法：本实验包括对36名正常健康志愿者及17例具有枕区病变患者的fMRI研究。在刺激和静止2种对比条件下采集枕区的回波平面图像。结果：主要视皮质位于双侧距状裂两侧 ,属于布劳德曼（Brodmann)17区。3例具有距状裂附近病变的患者的视皮质由于病变的占位效应而发生移位。结论：fMRI可用于在活体上脑上研究各功能区活动。视觉刺激下的fMRI可对人脑视皮质初步定位。由于病变占位效应的影响,病变周围的功能活动区常发生变形或移位。     

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.     

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。     

中文语言活动区功能磁共振研究

目的　利用BOLD功能磁共振 ,初步探索国人说汉语时大脑语言相关功能区。方法　对 2 2名正常中国人 ,说中文句子状态下进行BOLD磁共振脑功能成像 ,探索其大脑语言活动皮层相关功能区。结果　说中文时激活的脑区包括 :两侧运动区 ,左右侧额下回 ,左右侧颞上回 ,左侧岛叶及左右侧小脑半球。结论　BOLD功能磁共振可显示中文大脑活动相关皮层 ,是无创性研究人类语言的有力武器     

失语症病人皮层语言活动的功能MRI初步研究

目的用功能磁共振成像(fMRI)技术研究失语症患者皮层语言功能状态，并探讨该技术临床应用的可行性。方法在6位健康志愿者和3位处于恢复阶段的失语症患者完成词汇联想任务的同时，用fMRI技术测量局部神经元活动引起的脑区信号改变，分析处理成代表语言功能区的统计激活图。结果6例正常志愿者的语言加工活动激活了1个由额叶、顶叶、颞叶和枕叶等许多脑区组成的神经网络。而失语症患者无论左侧额叶有无病变，均无左侧额叶下部的激活。此外，2位患者显示了右侧大脑半球某些区域的激活，而这些区域没有参与正常志愿者的语言加工。结论失语症患者皮层语言功能存在脑内局部病灶的远隔效应和皮层语言功能区的重新分布或重组现象。fMRI技术是评价失语症患者语言功能的有效方法。     

磁共振脑功能成像在神经外科手术前后的应用价值

目的探讨功能性磁共振成像(fMRI)对手术前、后颅内病变累及运动中枢及其程度的诊断价值。方法选择45例经手术、病理证实的颅内占位性病变患者作为功能组,另20例颅内占位性病变手术患者为对照组;采用1.5T超导型MR成像仪,对功能组手术前、后行常规MRI及fMRI,对照组仅行常规MRI。结果45例功能组被检者均在脑fMRI中表现出局部的脑功能活动激活区,其中有22例运动皮层中枢的位置有不同程度移位,有23例运动皮层中枢未见明显移位改变;但手指运动功能区的分布并不会随病变类型而发生改变。病灶距功能区的距离与术前肌力呈正相关(r=0.553,P<0.001);与术后肌力无相关性(r=0.059,P>0.05);距离与肌力差呈负相关(r=-0.570,P<0.001)。术后有19例fMRI显示功能支配区较术前有不同程度增大;45例中无一例术后肌力降低,而对照组有5例(5/20)术后肌力降低。对照组手术前后肌力差平均值为(-0.05±0.69)级,功能组手术前后肌力差为(0.31±0.47)级,两者比较差异有统计学意义(t=2.473,P=0.016)。结论平均血氧水平依赖fMRI能清楚显示手运动皮层功能区,fMRI在术前提供了病变是否侵犯手运动皮质功能区的信息,为术中最大限度地保留功能区、避免和减少手术后并发症提供了客观依据;术前功能成像的应用对手术方案的制定及术后患者的功能恢复评估起指导作用。     

重症肌无力患者静息态脑功能磁共振成像与认知功能的研究

目的 运用静息态脑功能磁共振成像(rs-fMRI)技术探索重症肌无力患者(MG)脑功能局部一致性(Re-Ho)及认知功能的改变.方法 30例重症肌无力患者(MG组)和30例健康志愿者(对照组)分别进行rs-fMRI检查和临床量表评分.采用双样本t检验对两组受试者全脑的ReHo值及临床量表评分进行组间差异分析,MG患者异...     

BOLD—fMRI在视觉研究中的应用

BOLD—fMRI是利用磁共振成像技术探测大脑在不同刺激条件下，不同脑功能区神经活动相关生理变化的实验方法。它可以无创、直观地反映活体大脑功能，是研究脑功能相关视觉问题的一项新技术。对BOLD—fMRI的基本原理、技术特点及其在视觉研究中的应用做一综述。     

语言与音乐刺激下脑功能活动的MR功能成像研究

应用ＭＲ功能成像探测大脑功能活动的非对称性,方法用美国ＧＥ公司ＳｉｇｎａＨｏｒｉｚｏｎ磁共振成像系统及血氧水平依赖性方法,对１４例右利手受试者进行检查,Ｔ１ＷＩ应用自旋回波序列,准Ｔ２ＷＩ应用回波平面成像序列。应用ＳｕｎＳｐａｃｒｃ工作站,有关数据处理软件、ｔ检验及相关分析等统计学方法对数据进行处理。     

健康成人及脑肿瘤患者利手和非利手简单与复杂运动fMRI研究

目的:应用脑血氧水平依赖性功能MRI(BOLD-f MRI)研究健康成年人及脑肿瘤患者运动功能皮层定位并探讨其对脑肿瘤的临床应用价值。方法:10例健康志愿者和32例脑肿瘤患者(术前25例,术后7例)共42例受试者,行利手、非利手的单手握拳(简单运动)或单手对指(复杂运动)运动的脑BOLD-f MRI检查,分析脑肿瘤对运动皮层位置和功能的影响。结果:健康成人运动皮层主要位于对侧躯体感觉运动皮层(SMC),单或双侧辅助运动区(SMA)、运动前区(PMA)和双侧小脑半球。复杂运动或非利手运动时脑功能激活区范围和程度较简单运动或利手运动时增多。累及功能皮层的脑肿瘤患者,可见患侧部分脑功能区激活,但激活区移位、分布弥散。术后脑肿瘤患者功能皮层的位置基本恢复正常。结论:BOLD-f MRI是一种有效而无创的脑功能皮层定位方法,有利于脑肿瘤的精确定位诊断并指导临床治疗。     

急性期脑卒中患者和健康成人食指被动运动BOLD-fMRI

目的：对比分析急性期脑梗死患者与健康成人各运动相关脑区激活程度和方法的差异,探讨急性期脑梗死后运动功能变化的模式。方法：对12例基底节区急性期缺血性脑梗死患者（实验组）和与之相匹配的12例健康成人（对照组）进行食指被动运动BOLD-fMRI检查,然后应用SPM对功能图像进行处理分析,并选取初级感觉运动区（SM1）、次级感觉运动区（SM2）、运动前区（PM）、补充运动区（SMA）、扣带回运动区（CMA）及小脑作为兴趣区,观察两组受试者各运动相关脑区的激活情况,并对对侧SM1区的激活体积、激活率进行定量分析。结果：对照组主要激活对侧SM1区（激活体积中位数1006k,四分位间距1142k,激活率100％）,其它运动相关脑区激活次数较少,且激活体积相对较小;患者组主要激活对侧SM1区（激活体积中位数15k,四分位间距71k,激活率58．3％）,其它运动相关脑区偶尔或无激活。患者组对侧SM1激活率、激活体积均比对照组低（P〈0．05）。结论：BOLD-fMRI是一种研究脑梗死患者运动功能的有效方法。     

Influence of acoustic masking noise in fMRI of the auditory cortex during phonetic discrimination

The application of functional magnetic resonance imaging (fMRI) to study activation of auditory cortex suffers from one significant confounding factor, namely, that of the acoustic noise generated by the gradient system, which is an integral part of the imaging process. Earlier work has shown that it is indeed possible to distinguish cortical activation resulting from presentation of auditory stimuli despite the presence of background noise from the gradient system. The influence of acoustic noise from the gradient system of the MRI scanner on the blood oxygen level-dependent (BOLD) response during functional activation of the auditory cortex has been investigated in six healthy subjects with no hearing difficulties. Experiments were performed using gradient-echo echoplanar imaging (EPI) and a verbal, auditory discrimination paradigm, presented in a block-wise manner, in which carefully aligned consonant-vowel syllables were presented at a rate of 1 Hz. For each volunteer the experiment was repeated three times with all parameters fixed, except slice number, which was 4, 16, or 64. The positioning of the central four slices in each experiment was common. Thus, the fraction of TR during which the stimulus is on but no imaging is being performed, varies from almost zero, in the case of 64 slices, to over 8 seconds, in the case of four slices. Only the central four slices were of interest; additional slices simply generated acoustic noise and were discarded. During the four-slice experiment, all subjects showed a robust BOLD response in the superior temporal gyrus covering the primary and secondary auditory cortex. The spatial extent and the z-scores of the activated regions decreased with longer duration of gradient noise from the scanner. For a phonetic discrimination task, the results indicate that presentation of the stimulus during periods free from scanner noise leads to a more pronounced BOLD response.     

Clinical applications of functional MRI at 1.0 T: motor and language studies in healthy subjects and patients

In this article we describe clinical applications of functional MRI (fMRI) at 1.0 T. All experiments were performed on a commercially available 1.0-T system (Magnetom Impact Expert, Siemens AG, Erlangen, Germany) using a blood oxygen level-dependent (BOLD)-sensitive multi-slice EPI technique (TE 66 ms, 4 mm slice thickness, 210 mm field of view, 64 × 64 acquisition matrix). Different paradigms for localization of the motor cortex and for language lateralization were tested in healthy subjects and patients. Methodological considerations concerning the development of the paradigms are also described. In all healthy subjects, motor activation elicited BOLD signal changes in the sensorimotor cortex, permitting identification of primary motor and sensory cortical areas. Furthermore, focal activation of different cortical areas by a language task was possible in 6 of 10 subjects. Nineteen motor studies were performed in 18 patients with supratentorial lesions, in most cases prior to neurosurgical procedures. In 14 studies, fMRI results demonstrated the localization of the motor hand areas relative to the lesion. The results proved valuable for preoperative planning and contributed to therapeutical decisions. We conclude that functional MRI for clinically relevant applications, such as localization of motor and language function, is feasible even at a field strength of 1.0 T without dedicated equipment. Received: 5 May 1998; Revision received: 1 July 1998; Accepted: 13 July 1998     

Mapping functionally related regions of brain with functional connectivity MR imaging

BACKGROUND AND PURPOSE: In subjects who are performing no prescribed cognitive task, functional connectivity mapped with MR imaging (fcMRI) shows regions with synchronous fluctuations of cerebral blood flow. When specific tasks are performed, functional MR imaging (fMRI) can map locations in which regional cerebral blood flow increases synchronously with the performance of the task. We tested the hypothesis that fcMRI maps, based on the synchrony of low-frequency blood flow fluctuations, identify brain regions that show activation on fMRI maps of sensorimotor, visual, language, and auditory tasks. METHODS: In four volunteers, task-activation fMRI and functional connectivity (resting-state) fcMRI data were acquired. A small region of interest (in an area that showed maximal task activation) was chosen, and the correlation coefficient of the corresponding resting-state signal with the signal of all other voxels in the resting data set was calculated. The correlation coefficient was decomposed into frequency components and its distribution determined for each fcMRI map. The fcMRI maps were compared with the fMRI maps. RESULTS: For each task, fcMRI maps based on one to four seed voxel(s) produced clusters of voxels in regions of eloquent cortex. For each fMRI map a closely corresponding fcMRI map was obtained. The frequencies that predominated in the cross-correlation coefficients for the functionally related regions were below 0.1 Hz. CONCLUSION: Functionally related brain regions can be identified by means of their synchronous slow fluctuations in signal intensity. Such blood flow synchrony can be detected in sensorimotor areas, expressive and receptive language regions, and the visual cortex by fcMRI. Regions identified by the slow synchronous fluctuations are similar to those activated by motor, language, or visual tasks.     

Spontaneous brain activity in mild cognitive impairment revealed by amplitude of low-frequency fluctuation analysis: a resting-state fMRI study

Spontaneous low-frequency fluctuations (LFF) in the blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) signal have been shown to reflect cerebral spontaneous neural activity. The objective of this study was to explore brain functional changes in patients with mild cognitive impairment (MCI) by measuring the amplitude of the BOLD signals. Eighteen amnestic MCI patients and 20 healthy elderly individuals underwent the fMRI scan. The amplitude of LFF (ALFF) was calculated using REST software. MCI patients showed decreased ALFF in the right hippocampus and parahippocampal cortex, left lateral temporal cortex and right ventral medial prefrontal cortex and increased ALFF in the left temporal-parietal joint (TPJ) and inferior parietal lobule. The ALFF value in the right hippocampus and parahippocampal cortex was positively correlated with the scores of Mini-Mental State Exam. Reduced medial temporal lobe activity may implicate the underlying memory impairment mechanisms in MCI. Increased TPJ and inferior parietal lobule activity may indicate the compensatory mechanism in MCI patients. These findings suggest that ALFF analysis could provide a useful tool in the fMRI study of MCI.     

fMRI activation mapping as a percentage of local excitation: Consistent presurgical motor maps without threshold adjustment

Purpose

To evaluate the performance of a relative activation amplitude algorithm, versus standard t‐value thresholding, for reliably establishing the location, amplitude, and spatial extent of functional magnetic resonance imaging (fMRI) brain activation for presurgical planning.

Materials and Methods

Diagnostic fMRI maps from 42 neurosurgical patients performing a simple hand movement task were analyzed. Relative activation maps were made by normalizing statistical t‐value maps to the local peak activation amplitude within each functional brain region. The spatial distribution of activation was quantified and compared across mapping algorithms, subjects, and scan duration.

Results

Whereas the spatial distribution of blood oxygenation level‐dependent (BOLD) t‐value statistical activation maps was highly variable across subjects and scan duration, the spatial distribution of relative activation maps was highly reproducible both within individual subjects and across different subjects. In every case the 40% most active voxels in the cortical hand region were consistently localized to the pre‐ and postcentral gyri of the sensorimotor cortex.

Conclusion

The reproducibility and anatomical specificity of the spatiotemporal pattern of BOLD activation makes relative amplitude fMRI mapping a useful tool for clinical imaging, where accuracy, reproducibility, and quality control are critical concerns. J. Magn. Reson. Imaging 2009;29:751–759. © 2009 Wiley‐Liss, Inc.