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 / 中华放射学杂志

ABSTRACT

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 O.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 posterior cingulate 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 ± O.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.