老年阿尔茨海默病患者脑白质结构的扩散加权成像研究

目的:探讨磁共振扩散加权成像(DWI)评价阿尔茨海默病(AD)患者脑白质微结构改变的应用价值及该结构改变与患者认知功能损害的关系.方法:老年AD患者(AD组)及同期接受MRI检查无神经系统疾病或健康体检者(对照组)各30例,所有受检者均进行神经科查体和简易智能精神状态量表(MMSE)测试,对常规脑部MRI脑白质表现正常的部位行DWI检查,测量额叶白质、颞叶白质、顶叶白质、枕叶白质、胼胝体膝部和胼胝体压部6个兴趣区的平均弥散系数(ADC),并分析各部位ADC值与MMSE评分的关系.结果:AD组额叶自质、胼胝体压部、颞叶、顶叶的ADC值高于对照组(t分别为3.087、2.931、2.441和3.909,P＜0.05或P＜0.01),胼胝体膝部和枕叶ADC值与对照组比较差别无统计学意义(t分别为1.025和1.260,P＞0.05).AD组MMSE评分为(24.1±0.8)分,AD组顶叶白质、胼胝体压部、额叶白质的ADC值与MMSE评分呈负相关(r分别为-0.867、-0.670和-0.472,t分别为9.207,4.776,2.833,P＜0.05或P＜0.01),胼胝体膝部、颞叶白质、枕叶白质的ADC值与MMSE评分无直线相关性(r分别为-0.301、-0.308和-0.297,t分别为1.670,1.713,1.646,均P＞0.05).结论:对AD患者行定量DWI分析有助于评价AD常规MRI检查正常区域的微结构改变.老年痴呆患者认知功能的衰退与白质微结构密切相关,顶叶脑白质ADC值异常在认知功能损害早期更明显.

Diffusion-Weighted Imaging Study of Cerebral White Matter in Alzheimer's Disease

Objective:To elucidate the changes in apparent diffusion coefficients(ADC)by quantify diffusion weighted (DW)magnetic resonance imaging(MRI)in patients with Alzbeimer's disease(AD),and the relationship between micro-structure changes of white matter(WM)and the cognitive impairment thereof.Methods:The DW-MRI was performed in 30 probable AD patients and 30 normal controls with normal-appearing white matter(NAWM).The ADC was measured in different WM areas.The neurologic and neuropsychological assessments were examined with mini-mental state examination(MMSE)in patients.The ADC were determined in standard regions of the frontal,temporal,occipital and parietal white matter,genu,splenium of the corpus callosum.Results:The value of ADC was higher in frontal,splenium corpus callosum,temporal,and parietal white matter of AD group than that of control(P ＜ 0.01).There was no significant difference in the ADC value of genu and occipital white matter between AD and control groups(P＞ 0.05).The score of MMSE was 24.1±0.8 in AD group.The ADC values of parietal,splenium of the corpus callosum and frontal white matter were significantly negatively correlated with MMSE scores in AD group(P ＜ 0.05 or P ＜ 0.01).There was no correlation between the ADC values of genu of the corpus eallosum,temporal and occipital white matter with the MMSE score(P ＞ 0.05).Conclusion:The quantitative DWI analysis of MRI DWI may be helpful in assessing WM abnormalities in AD.The parietal WM abnormalities may play an important role in the development of dementia.It was showed that Alzheimer's cognitive decline with ADC value and micro-structure of white matter was closely related.