【摘要】 目的探讨在磁共振静息态功能成像中,基于同时多层面采集(simultaneous multi-slice,SMS)技术,研究重复时间(TR)对大脑比率低频振幅(f ALFF)测量结果的影响。方法纳入8名健康志愿者为研究对象,分别采用4种不同TR(2000、1500、1100及700 ms)的SMS-EPI扫描序列,采集4组静息态下脑功能成像数据,经头动校正、空间标准化,采用半高全宽的4 mm高斯核平滑等预处理后,进行f ALFF的计算并获得统计图,对测量结果进行组内单样本t检验及组间方差分析、配对样本t检验。结果单样本t检验显示4种TR序列下f ALFF统计图具有相似的分布模式,但经方差分析及配对样本t检验显示4组间f ALFF值存在差异且差异具有统计学意义(P<0.05,Alphasim校正)。TR=2000 ms较TR=1100、700 ms在枕叶、后扣带回的f ALFF值减低;TR=1500 ms较TR=1100、700 ms在枕叶、后扣带回及中央后回的f ALFF值减低;仅TR=1500、1100 ms较TR=700 ms在扣带回处f ALFF值增加;TR=2000 ms与TR=1500 ms差异无统计学意义。结论静息态脑功能磁共振成像中,采用短TR能够获得更多脑区神经元的活动信息;另外,应用SMS-EPI序列采集图像不仅能显著降低TR获得高时间分辨率图像,而且图像采样点个数也会增加。更多还原

【Abstract】 Objective To explore the effect of repetition time(TR) on fractional amplitude of low frequency fluctuation(f ALFF) under the resting state functional MRI based on Simultaneous Multi-Slice(SMS) technique.Methods 8healthy volunteers were enrolled.Four SMS echo planar imaging(SMS-EPI) sequences with different TR(2000、1500、1100 and 700ms) were applied to obtain the resting state functional magnetic imaging(rs-f MRI) data.After prepossessing(including corrected for head motion,spatially normalized to the Montreal Neurological Institute(MNI) space and smoothed with a full-width at half-maximum(FWHM) kernel of 4 mm,f ALFF was calculated and f ALFF map was produced.Then the one sample t-test,ANOVE or paired sample t-test were performed.Results The results of one sample ttest showed that f ALFF of four TR sequences have similar distribution mode.The results of ANOVA and paired sample t-test showed that there were statistically significant differences(P < 0.05,Alphasim correct) for f ALFF value.The value of f ALFF in the occipital lobe,posterior cingulate are lower at TR = 2000 ms,compared with TR = 1100,700 ms;The value of f ALFF in the occipital lobe,posterior cingulate and postcentral gyrus are lower at TR = 1500 ms compared with TR =1100,700 ms;The value of f ALFF in the cingulate are higher only at TR = 1500,1100 ms compared with TR = 700 ms;There was no statistically significant difference for the value of f ALFF at TR = 2000 ms and TR = 1500 ms.Conclusion In resting state functional MRI,the shorter TRs are able to get more neuron activity information.Additionally,SMS-EPI sequence can not only decrease TR greatly and obtain high temporal resolution image,but also allows the number of time point images to be higher.更多还原