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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。
Objective To investigate the effect of repetitive time (TR) on the measurement of low frequency amplitude (f ALFF) of cerebrospinal fluid ratio (SNR) based on Simultaneous Multi-slice (SMS) technique in restoring static magnetic resonance imaging. Methods Eight healthy volunteers were enrolled in this study. Four kinds of TR-2000 (1500, 1100, 1100 and 700 ms) SMS-EPI scanning sequences were used respectively to collect four sets of resting brain function imaging data. , Space standardization, preprocessing of 4 mm Gaussian kernel smoothing with full width at half maximum, f ALFF calculation and statistical chart were obtained. The results of single-sample t-test and inter-group variance analysis and paired sample t test were used to measure the results. Results The single-sample t-test showed that the f ALFF statistic patterns of four TR sequences had similar distribution patterns. However, the analysis of variance and paired samples t-test showed that f ALFF values differed between the four groups (P <0.05, Alphasim correction). TR = 2000 ms vs TR = 1100,700 ms At the occipital lobe, the posterior cingulate f fFFF decreases; TR = 1500 ms vs TR = 1100,700 ms f at the occipital lobe, posterior cingulate and f ALFF value decreased; only TR = 1500,1100 ms compared with TR = 700 ms in the cingulate f f ALFF value increases; TR = 2000 ms and TR = 1500 ms difference was not statistically significant. Conclusion In TRF with resting TR, more TR information can be obtained in more brain regions. In addition, using SMS-EPI to capture images not only significantly reduces the time-resolution of TR images, The number of points will also increase.