GRE OP和SE T1加权像在腰椎间盘突出症中的检查对比

目的比较梯度回波反相位T1加权(GRE OP T1WI)和自旋回波T1加权(SE T1WI)在腰椎间盘突出症中的应用效果。方法50例腰椎间盘突出症患者进行GRE OP T1WI和SE T1WI扫描。分别观察正常椎体、椎间盘、脑脊液、脊髓、腰椎附件在GREOP T1WI的表现,并对GRE OP T1WI和SE T1WI序列对突出椎间盘的信号和显示的清晰度进行比较。结果GRE OP T1WI所有椎间盘的信号均高于SE T1WI,GRE OP T1WI对椎间盘突出的显示比SE T1WI更清晰。结论GRE OP T1WI比SE T1WI更清晰快速地显示椎间盘突出症。     

颌下腺刺激前后扩散加权平面回波MRI功能成像

目的:研究扩散加权(DWI)平面回波成像(EPI)进行颌下腺成像的可行性,并描述其不同的功能状态。方法:27例健康志愿者在刺激前行扩散加权序列成像,给予口述柠檬汁刺激30s后重复扩散加权成像。所有检查均使用Siemens1.5T超导MR扫描仪(最大梯度场强为30mT/m,最大切换率为125mT/m/s),     

EPI序列的TE参数对功能磁共振成像激活信号的影响

目的 :探讨使用单次激励平面回波成像 (EPI)序列行功能磁共振成像 (fMRI)时 ,回波时间 (TE)对脑区激活信号的影响。方法 :正常被试者 7例 ,年龄 2 1.5～ 3 8.0岁 ,均为右利手。采用事件相关 (ER)设计方法 ,任务为右侧手指弹钢琴样序列运动。使用不同的TE时间进行EPI序列扫描 ,用SPM99软件包对扫描数据进行t检验以获取执行任务与静息状态对比的脑功能图像。比较TE 45ms、TE 5 5ms、TE 60ms时脑内运动区的血氧水平依赖对比的fMRI信号变化。结果 :3组不同TE情况下 ,以TE 45ms所获取的激活信号最强 ,最符合公认的激活部位。TE 5 5ms及 60ms所获得的激活信号均较弱。结论 :随TE不同 ,梯度EPI序列获取的fMRI激活信号大小及强度亦有改变 ,以TE为 45ms时得到的激活信号强度、范围及部位最佳。     

脑功能磁共振成像技术简介及针刺研究应用(二)

<正>4实验过程控制4.1序列、参数的选择fMRI对硬件的要求很高,目前fMRI研究大部分在1.5T以上的MRI机上进行。使用的扫描序列主要是梯度回波(GRE)序列和平面回波成像(EPI)序列。EPI更常用,其时间信噪比较高,可对全脑一次成像。但EPI对磁场的不均匀性非常敏感,需要强大的梯度系统支持。3.0T扫描仪采集到信号强度约较1.5T高50%左     

正常颈髓磁共振弥散加权成像的初步研究

目的　探讨正常人颈髓的磁共振弥散加权成像 (DWI)的可行性、技术特点及研究意义。资料与方法　对5名健康志愿者采用PhilipsGyroscanIntera 1 .5T磁共振系统 ,在平面回波成像 (EPI)基础上进行不同参数扫描 ,分析比较各自影像特点并计算平均表观弥散系数 (ADC)及相对ADC值 (RA比值 )。结果　采用层厚 5mm ,导航校正多次激发SE EPI弥散序列 (MS DWEPI)可以取得较好的颈髓DW图像 ,颈髓具有明显的各向异性 ,平行于白质纤维的弥散梯度可得到较高的ADC值。在颈髓矢状位成像测量的平均ADC值为 1 .0 6± 0 .1 3× 1 0 -3 mm2 /s(0 .86～ 1 .1 8×1 0 -3 mm2 /s) ,RA比值为 3.1 2± 0 .4 8(2 .5 6～ 5 .6 8)。结论　 1 .5T磁共振系统可以进行颈髓DWI,有望对脊髓疾病的机理研究和临床诊断提供新的帮助     

利用自旋回波平面成像T_2加权序列提高肝脏实性病变的检出率

目的　评价自旋回波平面成像 (SE EPI)T2 W序列对肝脏实性病变的检出能力。方法74例病人 (2 0 2个病灶 )接受肝脏 3种SE EPIT2 W序列磁共振扫描 ,评价其图像信噪比 (SNR)、肝脾对比噪声比 (L SCNR)、病灶对比噪声比 (CNR)及病变检出率 ,并与真实稳态进动快速成像 (true FISP)、快速自旋回波 (TSE)及半傅立叶采集单次激发快速自旋回波 (HASTE)等屏气T2 W序列相比较。结果SE EPI的SNR高于TSE (P <0 0 5 ) ,与true FISP相近 (P >0 0 5 ) ,但低于HASTE(P <0 0 1)。SE EPI序列的L SCNR及实性病变的CNR均显著高于true FISP、HASTE及TSE(P <0 0 1)。对于囊性病变 ,各序列间的检出率无明显差异 (P >0 0 5 )。各序列均检出所有直径大于 5cm的实性病变。直径 2～ 5cm的实性病变 ,SE EPI序列的检出率略高于true FISP、HASTE及TSE ,但无显著性差异 (P >0 0 5 )。直径小于 2cm的实性病灶 ,SE EPI序列的检出率 (93 9% )明显高于true FISP(5 7 6 % )、HASTE(71 2 % )及TSE(6 8 2 % ) (P <0 0 1)。结论　与其他屏气T2 W序列相比 ,SE EPIT2 WI有较高的病灶对比 ,能提高肝脏实性病变的检出率     

MR不同序列诊断早期脊柱转移瘤的价值

目的:探讨MR不同序列在诊断早期脊椎转移瘤中的价值.方法:25例临床怀疑脊柱转移瘤患者行脊柱磁共振检查,磁共振扫描序列包括自旋回波(SE)T1WI、快速自旋回波(TSE)序列T2WI、快速翻转恢复序列(STIR)、梯度回波(GRE)序列二维多回波聚合(Me-2D).结果:25例均发现脊柱转移瘤病灶,共73个椎体和45个附件受累.椎体的异常在各序列图像显示情况不同,T1WI显示73个异常椎体,T2WI显示55个,STIR显示69个,Me-2D显示73个.在T1WI序列图像有24个椎体表现为弥漫性异常信号,49个椎体局部信号异常.Me-2D序列显示椎体局部受累病灶边缘及骨小梁结构清晰.结论:SE T1WI,TSE T2WI及GRE Me-2D序列结合能够更敏感地发现椎体受累早期改变.     

颅内出血性病变:用0.5T和1.5T SE和GR MRI的评价

作者对20例典型的颅内出血(50处病变)的MR表现作3回顾性分析。MRI使用两种场强(0.5T和1.5T)、SE(自旋回波序列)和GR(梯度聚焦回波序列)T_2加权。两种场强的SE T_2加权TR/TE均为500/30,T_2加权TR/TE为250/30,60,层厚在0.5T和1.5T分别为8mm和7mm,层面间隔为层厚的10%;两种场强的GR T_2~*加权TR/TE均为500/35,层厚10mm,使用35°翻转角。根据两种场强三种序列的检查所见,作者认     

低场强MRI对主动脉夹层的诊断价值

目的 评价低场强磁共振成像对主动脉夹层的诊断价值。方法 对16例主动脉夹层在低场强MRI自旋回波（SE）序列和梯度回波（GRE）表现进行回顾性分析总结，其中，6例经手术病理证实。结果 16例均能清晰显示病变的范围、夹层起始部位、内膜片、真假腔，6例假腔内显示血栓。结论 低场强MRI作为一种无创性检查能对主动脉夹层作出准确及时的诊断。     

脑膜瘤相对血流量MR定量检测:梯度回波与平面回波序列法的比较

目的通过对梯度回波序列法与平面回波(echoplanerimaging,EPI)序列法重建脑膜瘤相对血流量图的比较,对脑膜瘤相对血流量的定量检测进行评价。方法应用西门子1.5TMR仪对18例脑膜瘤病人进行检查,获取常规的T1WI、T2WI和增强T1WI,以及动态的磁顺应敏感图像(T2WI梯度回波序列或SEEPI序列)。在采集动态的磁顺应敏感图像期间(梯度回波法12例,EPI法6例),应用程控注射器以每秒5ml的流率注入钆喷替酸葡甲胺(GdDTPA)(0.2mmol/kg)。应用优视系统(advancedvisualsystem,AVS)软件逐点处理动态的磁顺应敏感资料,对重建的全部相对血流量图作感兴趣区分析,通过借鉴文献中脑灰质血流量数值,定量计算脑膜瘤的相对血流量。结果肿瘤相对血流量与脑灰质相对血流量的比率是3.01±1.18(梯度回波序列法为3.07±1.39;EPI序列法为2.84±0.94)。脑膜瘤的平均相对血流量为(14.47±5.96)ml/100g:梯度回波序列法为(14.85±6.72)ml/100g,EPI序列法为(13.72±4.54)ml/100g;梯度回波序列法与EPI序列法的结果比较差异无统计学意义(t=0.42,P=0.68)。结论应用脑灰质血流量数值法可便捷地定量检测脑膜瘤的相对血流量,脑膜瘤的相对血流量明显增高而且非均匀性;血脑屏障破坏情况下,仍可估算相对血流量值;尽管EPI序列法更具有效应,梯度回波序列法和EPI序列法均能有效地应用于相对血流量的测定。     

Spatial and temporal characteristics of physiological noise in fMRI at 3T

RATIONALE AND OBJECTIVES: Physiological noise in blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) has been shown to have characteristics similar to the BOLD signal itself, suggesting that it may have a vascular dependence. In this study, we evaluated the influence of physiological noise in fMRI as revealed by the differences in vasculature sensitivity of gradient-echo echo-planar imaging (GE-EPI) and spin-echo EPI (SE-EPI). MATERIALS AND METHODS: The contribution of physiological noise to the fMRI signal during activation of the visual cortex was assessed by comparing its temporal characteristics with respect to echo time (TE), using both GE-EPI and SE-EPI. The correlation of the noise in fMRI with apparent diffusion coefficient (ADC) and the number of components required to describe its variance, as determined by principal-component analysis (PCA), were also assessed. RESULTS: The SE-EPI data were less affected by a TE-dependence of noise, in contrast to the apparent physiological noise in GE-EPI. Voxel-wise analysis revealed that total apparent noise increased as ADC values increased, and the relationship was different for GE-EPI and SE-EPI. PCA revealed that while the number of components characterizing the noise in SE-EPI data increased in a TE-dependent manner, approaching that of white noise at long echo time, the number of components from GE-EPI data was TE-independent. CONCLUSIONS: The difference in sensitivities to physiological noise between SE-EPI and GE-EPI suggests that extravascular BOLD processes around draining veins contribute significantly to physiological noise in BOLD fMRI, and the suppression of this noise component may enhance SE-EPI BOLD sensitivity at higher fields.     

BOLD fMRI of the visual cortex: quantitative responses measured with a graded stimulus at 1.5 Tesla

PURPOSE: To measure and quantitatively characterize an activity generated by the neurons of the visual cortex (VC) in response to graded luminous intensity contrast stimuli using a 1.5 Tesla scanner. MATERIALS AND METHODS: Functional magnetic resonance imaging (fMRI) of the vc with the intrinsic blood oxygenation level dependent (BOLD) mechanism was performed by using a paradigm with a 5 x 5 flashing checkerboard pattern flickering eight times per second at eight luminance contrasts presented in a randomized order. The changes of the luminance contrast were obtained by varying the luminance intensity of the white checkerboard squares. Each of eight trials, corresponding to eight luminance contrasts, consisted of six "rest" and six "activation" epochs, repeated five times, amounting to 60 measurement periods per trial. During each epoch, 10 contiguous oblique axial-to-coronal slices covering the calcarine fissure region and parallel to a line through the anterior-posterior commissure (AC-PC) markers were acquired using a gradient-recalled echo planar imaging (GRE-EPI) sequence. RESULTS: The measurements showed changes in the activation extent in the VC following the stimulus' rising luminance intensity contrast. In addition, the fMRI signal in those activated areas present throughout all eight trials, referred to as "common" voxels in this report, showed an increasing trend as a function of the rising luminance intensity contrast. CONCLUSION: These results suggest that the processes of the neuronal recruitment that affects the extent and number of activated neurons, and the neuronal enhancement that defines the magnitude of the neuronal activation are dependent on the luminance intensity contrast. These changes can be visualized and quantified using BOLD fMRI at 1.5 Tesla.     

Disparity of activation onset in sensory cortex from simultaneous auditory and visual stimulation: Differences between perfusion and blood oxygenation level-dependent functional magnetic resonance imaging

PURPOSE: To compare the temporal behaviors of perfusion and blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in the detection of timing differences between distinct brain areas, and determine potential latency differences between stimulus onset and measurable fMRI signal in sensory cortices. MATERIALS AND METHODS: Inversion recovery (IR) spin-echo echo-planar imaging (EPI) and T2*-weighted gradient-echo EPI sequences were used for perfusion- and BOLD-weighted experiments, respectively. Simultaneous auditory and visual stimulations were employed in an event-related (ER) paradigm. Signal time courses were averaged across 40 repeated trials to evaluate the onset of activation and to determine potential differences of activation latency between auditory and visual cortices and between these scanning methods. RESULTS: Temporal differences between visual and auditory areas ranged from 90-200 msec (root-mean-square (RMS) = 134 msec) and from -80 to 930 msec (RMS = 604 msec) in perfusion and BOLD measurements, respectively. The temporal variability detected with BOLD sequences was larger between subjects and was significantly greater than that in the perfusion response (P < 0.04). The measured time to half maximum (TTHM) values for perfusion imaging (visual, 3260 +/- 710 msec; auditory, 3130 +/- 700 msec) were earlier than those in BOLD responses (visual, 3770 +/- 430 msec; auditory, 3360 +/- 460 msec). CONCLUSION: The greater temporal variability between brain areas detected with BOLD could result from differences in the venous contributions to the signal. The results suggest that perfusion methods may provide more accurate timing information of neuronal activities than BOLD-based imaging.     

Functional magnetic resonance imaging of the human brain based on signal enhancement by extravascular protons (SEEP fMRI).

Functional magnetic resonance imaging (fMRI) studies of the human brain were carried out at 3 Tesla to investigate an fMRI contrast mechanism that does not arise from the blood oxygen-level dependent (BOLD) effect. This contrast mechanism, signal enhancement by extravascular protons (SEEP), involves only proton-density changes and was recently demonstrated to contribute to fMRI signal changes in the spinal cord. In the present study it is hypothesized that SEEP fMRI can be used to identify areas of neuronal activity in the brain with as much sensitivity and precision as can be achieved with BOLD fMRI. A detailed analysis of the areas of activity, signal intensity time courses, and the contrast-to-noise ratio (CNR), is also presented and compared with the BOLD fMRI results. Experiments were carried out with subjects performing a simple finger-touching task, or observing an alternating checkerboard pattern. Data were acquired using a conventional BOLD fMRI method (gradient-echo (GE) EPI, TE = 30 ms), a conventional method with reduced BOLD sensitivity (GE-EPI, TE = 12 ms), and SEEP fMRI (spin-echo (SE) EPI, TE = 22 ms). The results of this study demonstrate that SEEP fMRI may provide better spatial localization of areas of neuronal activity, and a higher CNR than conventional BOLD fMRI, and has the added benefit of lower sensitivity to field inhomogeneities.     

Theoretical noise model for oxygenation-sensitive magnetic resonance imaging.

Contrast-to-noise ratio (CNR) in blood oxygenation level-dependent (BOLD) based functional MRI (fMRI) studies is a fundamental parameter to determine statistical significance and therefore to map functional activation in the brain. The CNR is defined here as BOLD contrast with respect to temporal fluctuation. In this study, a theoretical noise model based on oxygenation-sensitive MRI signal formation is proposed. No matter what the noise sources may be in the signal acquired by a gradient-echo echo-planar imaging pulse sequence, there are only three noise elements: apparent spin density fluctuations, S(0)(t); transverse relaxation rate fluctuations, R(2) (*)(t); and thermal noise, n(t). The noise contributions from S(0)(t), R(2) (*)(t), and n(t) to voxel time course fluctuations were evaluated as a function of echo time (TE) at 3 T. Both noise contributions caused by S(0)(t) and R(2) (*)(t) are significantly larger than that of thermal noise when TE = 30 ms. In addition, the fluctuations between S(0)(t) and R(2) (*)(t) are cross-correlated and become a noise factor that is large enough and cannot be ignored. The experimentally measured TE dependences of noise, temporal signal-to-noise ratio, and BOLD CNR in finger-tapping activation regions were consistent with the proposed model. Furthermore, the proposed theoretical models not only unified previously proposed BOLD CNR models, but also provided mechanisms for interpreting apparent controversies and limitations that exist in the literature.     

High-resolution fMRI using multislice partial k-space GR-EPI with cubic voxels.

The premises of this work are: 1) the limit of spatial resolution in fMRI is determined by anatomy of the microcirculation; 2) because of cortical gray matter tortuosity, fMRI experiments should (in principle) be carried out using cubic voxels; and 3) the noise in fMRI experiments is dominated by low-frequency BOLD fluctuations that are a consequence of spontaneous neuronal events and are pixel-wise dependent. A new model is proposed for fMRI contrast which predicts that the contrast-to-noise ratio (CNR) tends to be independent of voxel dimensions (in the absence of partial voluming of activated tissue), TE, and scanner bandwidth. These predictions have been tested at 3 T, and results support the model. Scatter plots of fMRI signal intensities and low-frequency fluctuations for activated pixels in a finger-tapping paradigm demonstrated a linear relationship between signal and noise that was independent of TE. The R(2) value was about 0.9 across eight subjects studied. The CNR tended to be constant across pixels within a subject but varied across subjects: CNR = 3.2 +/- 1.0. fMRI statistics at 20- and 40-ms TE values were indistinguishable, and TE values as short as 10 ms were used successfully. Robust fMRI data were obtained across all subjects using 1 x 1 x 1 mm(3) cubic voxels with 10 contiguous slices, although 1.5 x 1.5 x 1.5 mm(3) was found to be optimum. Magn Reson Med 46:114-125, 2001.     

猴可复性大脑中动脉闭塞模型脑缺血半暗带的血氧水平依赖效应

目的 探讨血氧水平依赖(BOLD)MRI对确定猴脑缺血半暗带(IP)的价值.方法 成年恒河猴6只,应用微导管法制作猴可复性大脑中动脉闭塞(MCAO)模型.MCAO后0 h、再灌注后1、3、 6、 12、24及48 h分别进行DWI、PWI、T_2 WI、定量T_2和T_2~* 扫描,根据T_2和T_2~* 图计算可逆性横向弛豫率(R_2'),用来表示BOLD效应(R_2' BOLD).计算动脉闭塞期DWI(0 h DWI)、再灌注48 hT_2WI(48 h T_2WI)及脑组织大体切片2,3,5-氯化三苯基四氮唑(TTC)染色病灶体积百分比(病灶体积/双侧大脑半球体积).将缺血组织划分为3个区域:梗死核心(0 h DWI、48 h T_2WI均为高信号区)、IP(0 h DWI高信号,48 h T_2WI等信号区)及低灌注区(0 h平均通过时间延长但0 h DWI、48 hT_2WI均为等信号区),分别测最3个区域R_2'的相对值(患侧/健侧半球镜影区比值,rR_2').病灶体积比比较采用配对t检验和相关分析,3个区域rR_2'比较采用单因素方差分析.结果 6只猴中4只造模成功.48 h _T2WI病灶体积比(8.16±0.55)%较0 h DWI的(11.37±1.41)%明显缩小(t=6.472,P<0.05);TTC染色病灶体积比(8.15±0.62)%与48 h T_2WI的(8.16±0.55)%差异无统计学意义(t=0.150,P>0.05),两者呈明显正相关(r=0.98,P<0.05).梗死核心、IP、低灌注区rR_2'在各时间点差异均有统计学意义,梗死核心低于IP,IP低于低灌注区(P<0.05),三者rR_2'值:0 h时分别为1.129±0.108、1.329±0.081、1.584±0.103(F=36.19,P<0.05).1 h分别为0.668±0.082、1.237±0.072、1.435±0.066(F=134.09,P<0.05).3 h分别为0.536±0.075、1.453±0.081、1.770±0.141(F=256.30,P<0.05).6 h分别为0.259±0.050、2.435±0.131、2.957±0.177(F=803.25,P<0.05).12 h分别为0.385±0.054、2.447±0.148、3.254±0.184(F=743.74,P<0.05).24 h分别为0.083±0.026、1.968±0.127、3.101±0.144(F=1236.26,P<0.05).48 h分别为0.246±0.058、3.694±0.218、4.297±0.322(F=557.02,P<0.05).随再灌注时间延长,IP和低灌注区的rR_2'呈逐渐升高趋势,表现为负性BOLD效应;梗死核心呈逐渐降低趋势,表现为正性BOLD效应.结论 R_2' BOLD可以根据缺血脑组织氧代谢状态的不同来区分IP和梗死核心.     

Comparison of simultaneously measured perfusion and BOLD signal increases during brain activation with T(1)-based tissue identification.

Perfusion and blood oxygenation level-dependent (BOLD) signals were simultaneously measured during a finger-tapping task at 3T using QUIPSS II with thin-slice TI(1) periodic saturation, a modified pulsed arterial spin labeling technique that provides quantitative measurement of perfusion. Perfusion and BOLD signal changes due to motor activation were obtained and correlated with the T(1) values estimated from echo-planar imaging (EPI)-based T(1) maps on a voxel-by-voxel basis. The peak perfusion signal occurs in voxels with a T(1) of brain parenchyma while the peak BOLD signal occurs in voxels with a T(1) characteristic of blood and cerebrospinal fluid. The locations of the peak signals of functional BOLD and perfusion only partially overlap on the order of 40%. Perfusion activation maps will likely represent the sites of neuronal activity better than do BOLD activation maps. Magn Reson Med 44:137-143, 2000.     

Diffusion-weighted imaging of the brain: comparison of stimulated- and spin-echo echo-planar sequences

We used a rat model of focal cerebral ischaemia to compare stimulated-echo (STE) and spin-echo (SE) echo planar (EPI) diffusion-weighted sequences as regards image quality and accuracy of calculation of apparent diffusion coefficients (ADC). Focal cerebral ischaemia was induced by endovascular occlusion of the middle cerebral artery in five rats. MRI was performed on a 2.35 tesla imager. For diffusion-weighted imaging (DWI) we used STE-EPI and SE-EPI with different diffusion times (Δ) of 15, 30, 45, 60, 75 and 90 ms using values of b of 200, 300, 400, 500, 600 and 700 s/mm². We assessed image quality, the signal-to-noise-ratio (SNR) and the accuracy of the ADC calculated from both sequences. Infarcts were delineated in all cases, independent of sequence type and Δ. The image quality and SNR of the SE-EPI images were significantly better, with a higher SNR than STE-EPI images for short and intermediate values of Δ. However, when Δ reached 75 ms STE-EPI became superior to SE-EPI. ADC calculated from STE-EPI images were smaller than those from SE-EPI images for short and intermediate diffusion times, possibly because of the lower SNR of the former. We suggest that SE-EPI sequences be used for DWI of the brain, particularly on experimental systems and whole-body imagers with enhanced gradient hardware, where it is possible to run highly diffusion-weighted sequences (b > 500 s/mm²) with Δ less than 50 ms. However, when using very long values of Δ because of hardware restrictions or for measurement of restricted diffusion, STE sequences give better results. Received: 17 August 2000 Accepted: 5 December 2000     

Localized echo-volume imaging methods for functional MRI

To perform true three-dimensional activation experiments in the human brain, dedicated localized echo-volume imaging (L-EVI) methods were developed. Three-dimensional acquisition allows generation of activation maps with minimal vascular enhancement related to inflow effects. The rapid acquisition of the L-EVI (～100 msec) reduces signal instabilities caused by motion, facilitating the detection of the small intensity changes expected with brain activation. Single-shot L-EVI was performed on normal volunteers at 1.5 T, imaging a three-dimensional predefined volume (240 × 45 × 45 mm³) in the superior portion of the brain with a spatial resolution of 3.75 × 5 × 5 mm³. Increased brain coverage was achieved with a multi-volume imaging (three-shot) version, which simultaneously achieved effective suppression of signals from cerebrospinal fluid. In addition, both asymmetric spin-echo (ASE) and spin-echo (SE) versions of the technique were used to detect blood oxygenation level dependent (BOLD) signal changes in the motor cortex with a finger-tapping paradigm. Images obtained by the L-EVI sequence were qualitatively comparable to standard multislice two-dimensional echo-planar images. Both ASE and SE functional MRI (fMRI) experiments showed consistent activation in the contralateral primary sensorimotor cortex. Furthermore, significant differences in location and magnitude of activation was observed between the two methods, confirming theoretical predictions.