局部回指数在阿尔茨海默病早期诊断的应用研究

摘要

目的 探讨局部回指数(LGI)对阿尔茨海默病(AD)早期诊断的价值.方法 选取2011年3月至2013年9月至复旦大学附属华山医院就诊的35例遗忘型轻度认知障碍(aMCI)患者、34例轻度AD患者及33名正常对照进行简易精神状态检查(MMSE)及高分辨率结构MRI检查.应用FreeSurfer基于表面的形态学测量(SBM)的方法处理得到每个被试大脑表面各顶点的LGI,并对每个被试左右大脑半球的LGI分别求均值得到平均LGI(mLGI).将年龄、性别及受教育年限作为协变量,应用协方差分析比较3组被试间左右大脑半球的mLGI差异,应用Bonferroni进行两两组间比较;3组被试LGI的组间差异应用协方差分析,结果用蒙特卡洛方法进行多重比较校正,并计算3组被试的MMSE评分与LGI的相关性.结果 轻度AD组左右大脑半球的mLGI(左脑2.94±0.11,右脑2.93± 0.10)较正常对照组(左脑3.03±0.12,右脑3.02±0.13)均降低(P<0.05);aMCI组左右大脑半球的mLGI (左脑2.96±0.10,右脑2.96±0.09)与正常对照组差异均无统计学意义(P>0.05),与轻度AD组差异也均无统计学意义(P>0.05).aMCI组与正常对照组相比,右侧颞叶、双侧额叶及顶叶部分脑区LGI降低.轻度AD组与aMCI组相比,双侧颞叶、枕叶、额叶及右侧顶叶部分脑区LGI减低.3组的LGI在双侧颞叶、枕叶、左侧额叶及右侧顶叶部分脑区与MMSE评分呈正相关.结论 LGI为AD的早期诊断及病情监测提供可参考的影像学依据.%Objective To evaluate the role of local gyrification index (LGI) in the early diagnosis of Alzheimer disease(AD). Methods Thirty‐five amnestic‐type mild cognitive impairment patients (aMCI group), 34 mild AD patients (mild AD group) and 33 healthy volunteers (normal control group) were studied. All patients underwent high resolution MRI examination and mini‐mental state examination (MMSE). Using surface‐based morphometry, the FreeSurfer was employed to access LGI of vertex over every participant′s whole cortical surface, then we calculated the mean LGI (mLGI) of each subject′s left and right hemisphere separately. Taking age, gender and educational year as covariance, analysis of covariance was used to compare the difference of mLGI of left and right brain among 3 groups, then Bonferroni was done between every two groups. Analysis of covariance was applied to compare the difference of LGI of every participant among 3 groups, and Monte Carlo method was employed to perform multiple comparison corrections. The correlations between the MMSE scores and LGIs of the three groups were analyzed. Results Compared with normal control group(left 3.03±0.12,right 3.02±0.13), the mLGI of hemispheres in mild AD group(left 2.94±0.11,right 2.93±0.10) decreased respectively(P<0.05). The difference of mLGI of hemispheres between aMCI group(left 2.96 ± 0.10, right 2.96 ± 0.09) and normal control group had no statistical significance(P>0.05). The difference of mLGI of hemispheres between aMCI group and mild AD group also had no statistical significance(P>0.05). The aMCI group showed decrease of LGI in some brain regions located at the right temporal lobe, bilateral frontal and parietal lobe compared with the normal control group. While compared with aMCI group, decreased LGIs was presented in some brain regions located at bilateral temporal, occipital, frontal lobe and the right parietal lobe of mild AD group. There was a positive correlation between MMSE scores and LGIs of some brain regions in the bilateral temporal, occipital lobe, the left frontal lobe and the right parietal lobe in the three groups. Conclusion LGI is conductive in the early diagnosis of AD and can serve as an imaging marker for monitoring disease progresses.