老年人脑白质结构的扩散张量成像研究

目的应用扩散张量成像（diffusion tensor imaging，DTI）阐明老年人脑白质结构平均弥散系数（ADCavg）和部分各向异性（FA）的变化。方法老年组及非老年组各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，无影响神经系统的疾病。所有受检者均行DTI检查，选择额叶白质、顶叶白质、半卵圆中心、胼胝体膝部、胼胝体压部为兴趣区，定量测量ADCavg与FA值。结果ADCavg、FA值男、女性别差异无统计学意义（P〉0．05），左右半球无明显改变。随着年龄增长，ADCavg值与年龄呈正相关，FA值与年龄呈负相关。在额叶白质（ADCavg：r=0．449，P〈0．05；FA：r=0．350，P〈0．05）、半卵圆中心（ADCavg：r=0．347，P〈0．05；FA：r=0．409，P〈0．05）、胼胝体膝部（ADCavg：r=0．452，P〈0．01；FA：r=0．556，P〈0．01）、压部（ADCavg：r=0．296，P〉0．05；FA：r=0．289，P〉0．05）、顶叶白质（ADCavg：r=0．367，P〈0．05；FA：r=0．287，P〉0．05）。老年组额叶白质、胼胝体膝部、半卵圆中心的ADCavg、FA值与简易智能精神状态量表（MMSE）相关，尤其是额叶白质的FA值相关更显著（r=0．466，P〈0．01）。结论与年龄相关的定量DTI分析，可有助于评价与年龄相关的变化。并且可建立一个与神经变性疾病比较对照的标准。DTI功能与结构的结合，表明老年人认知功能的衰退与白质微结构密切相关。

The cerebral white matter in the elderly in diffusion tensor imaging study

Objective To elucidate the changes in apparent diffusion coefficients (ADCavg) and fraction anisotropy (FA) by quantify diffusion tensor (DT) magnetic resonance imaging (MRI) in the elderly. Methods DT MRI was performed in 30 normal elderly people and 30 non-elderly controls. Subjects were examined by neurologic and neuropsychological assessment with mini-mental state examination (MMSE). No disorder affecting the central nervous system was found. ADCavg and FA were determined in standard regions of the frontal and parietal white matter, genu, splenium of the corpus callosum and centrum semiovale. Results On DTI, there was no significant difference in the values of ADCavg or FA either between male and female, or between the right and left hemisphere (all P>0. 05). ADCavg increased and FA declined significantly with aging: frontal (ADCavg: r=0. 449, P<0.05; FA: r=0.350, P<0.05), centrum semiovale (ADCavg: r = 0.347, P<0.05;FA: r=0.409, P<0. 05), genu of the corpus callosum (ADCavg: r=0. 452, P<0. 01;FA: r=0. 556, P<0.01), splenium (ADCavg: r=0.296, P>0.05;FA: r = 0.289, P>0.05), parietal (ADCavg: r=0. 367, P<0. 05;FA: r=0. 287, P>0. 05). ADCavg and FA of genu of the corpus callosum and centrum semiovale correlated significantly with MMSE scores. Conclusions Quantitative DT analysis may be helpful in assessing normal age-related changes.