采用MR低频振幅图像和低频振幅分数图像观察阿尔茨海默病患者静息态脑功能改变

Resting-state functional MR changes in Alzheimer＇s disease patients visualized by amplitude of low- frequency fluctuation and fraction of amplitude of low-frequency fluctuation

目的采用逐体素分析方法研究阿尔茨海默病（AD）患者MR低频振幅（ALFF）图像和低频振幅分数（fALFF）图像上的异常改变，及其与简易智能状态检查（MMSE）评分的相关性。方法31例AD患者和44例正常志愿者参加研究，采用平面回波序列和32通道头线圈采集静息状态下受试者的血氧水平依赖法（BOLD）脑功能成像数据，经过预处理头动校正，空间标准化，8mm高斯核平滑运算后，采用静息态脑功能成像软件包REST1．6计算获得ALFF图像和fALFF图像，采用统计参数图（SPM5）软件包进行基于一般线性模型的独立样本t检验，观察AD患者和正常对照组的组间图像差异，并与MMSE评分进行Pearson相关性分析，体素水平的阈值设为未校正的0．001，簇水平上的校正水准为0．05。结果AD患者ALFF值在左侧颞叶（0．492±0．119）、右侧扣带回（0．434±0．093）较正常对照组（分别为0．443±0．068、0．380±0．081）增高，差异有统计学意义（t值分别为2．227、2．658，P值均〈0．05），AD患者双侧楔前叶和左侧中央旁小叶fALFF值（1．167±0．203）低于正常对照组（1．453±0．269），差异有统计学意义（t=5．001，P〈0．05），AD患者双侧颞叶fALFF（左侧1．226±0．127，右侧1．146±0．214）高于正常对照组（左侧1．134±0．088，t=3．695，P〈0．05；右侧1．014±0．132，t=3．285，P〈0．05），以左侧为著，差异有统计学意义。双侧颞叶ALFF及fALFF均与MMSE评分呈正相关（r值为0．768～0．909，P值均〈0．05），左侧范围更大。结论AD患者颞叶静息态脑功能活动水平增高，与MMSE评分呈正相关，具有左侧优势，提示左侧颞叶是静息态脑功能成像诊断和随访AD患者疾病进展程度的最佳观察部位。

Objective To investigate the difference of amplitude of low-frequency fluctuation （ALFF） and fraction of amplitude of low-frequency fluctuation（fALFF） between Alzheimer＇s disease （AD） patients and normal aging （NA） controls by voxel-based analysis. Methods Thirty-one AD patients and 44 NA controls were enrolled in the study. Blood oxygen level dependent functional （BOLD） EPI data were obtained during resting-state by using 32-channel head coil. Data were realigned, normalized and then smoothed with 8 mm FWHM kernel. Resting-state fMRI toolkit（ version 1.6 ） was used to generate ALFF and fALFF images. Independent two sample t-test was performed with SPM5 to compare ALFF and fALFF of AD and NA controls. Pearson correlation analysis was performed to examine the relationship between MMSE score and ALFF,fALFF parameters. The significance level was set to be uncorrected 0. 001 on the voxel level and 0. 05 on the cluster level. Results AD patients showed increased ALFF in left temporal lobe （0. 492 ± 0. 119 ） and right cingulated cortex（0. 434± 0. 093 ） of AD patients, which were 0. 443 ± 0. 068 and 0. 380 ±0. 081 in NA controls （ t = 2. 658,2. 227, P 〈 0. 05 ）. Decreased fALFF was found in bilateral posteriorcingulate cortices （1. 167 ± 0. 203 ） and increased fALFF was found in bilateral temporal lobes （left 1. 226 ±0. 127,right 1. 146 ±0. 214） with left side dominance,which were 1. 453±0. 269,1. 134 ±0. 088, 1. 014 ±0. 132 in NA controls （t = 5. 001,3. 695,3. 285,P 〈0. 05）. Bilateral temporal ALFF and fALFF correlated with MMSE positively （ r = 0. 768-0. 909, P 〈0. 05 ） with left dominance. Conclusion AD patients showed increased resting-state functional MRI changes correlated with MMSE score in the temporal lobes with left dominance, which indicated left temporal lobe may be the best location for the observation of disease progression in AD patients.