摘要：

目的 应用扩散张量成像（DTI）研究阿尔茨海默病和遗忘型轻度认知损害患者白质和颞干纤维束部分各向异性（FA）值变化特点，探讨颞干纤维束损伤机制及其对阿尔茨海默病和遗忘型轻度认知损害的诊断与鉴别诊断价值。方法 应用常规MRI 和DTI 测量阿尔茨海默病（10 例）、遗忘型轻度认知损害（10 例）和正常对照者（10 例）颞干纤维束（包括前连合、钩束、额枕下束）及前额叶、颞叶、顶叶、枕叶白质FA 值，比较各组受试者左右侧对称部位白质和颞干纤维束FA 值变化。结果 各组受试者左右侧对称部位白质和颞干纤维束FA 值差异无统计学意义（均P > 0.05），但其前连合、钩束、额枕下束及前额叶白质FA 值差异具有统计学意义（均P < 0.05）。其中，阿尔茨海默病组前连合、钩束、额枕下束FA值低于遗忘型轻度认知损害组（均P < 0.05），前连合、钩束、额枕下束及前额叶、顶叶白质FA 值低于正常对照组（均P < 0.05）；而遗忘型轻度认知损害组与正常对照组前连合、钩束、额枕下束及前额叶白质FA值差异无统计学意义（均P > 0.05）。结论 阿尔茨海默病和遗忘型轻度认知损害患者与正常老年人颞干纤维束FA 值存在显著差异，提示颞干纤维束在阿尔茨海默病患者白质损伤中具有重要意义，DTI 检查有助于阿尔茨海默病与遗忘型轻度认知损害和正常老龄化的鉴别诊断。阿尔茨海默病前连合、钩束、额枕下束及前额叶、顶叶白质FA 值异常具有良好的临床诊断价值。

关键词: 阿尔茨海默病, 认知障碍, 记忆障碍, 颞叶, 磁共振成像

Abstract:

Objective  To study the changes of fractional anisotropy (FA) value of white matter of brain and temporal stem in Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI) patients as well as normal cognitive (NC) aged people with diffusion tensor imaging (DTI), and explore the damage mechanism of temporal stem and its diagnostic value on AD and aMCI.  Methods  Ten patients with AD, 10 patients with aMCI and 10 NC volunteers as control group were scanned by routine MRI and DTI. FA values were calculated by post-processing software (DTIstudio) in temporal stem (including anterior commissure, uncinate fasciculus and inferior occipitofrontal fasciculus), and white matter in anterior frontal, temperal, parietal and occipital lobes. The data were analyzed by SPSS 13.0. If bilateral differences of FA values were not statistically significant (P > 0.05), the average values of bilateral FA were selected and compared among 3 groups. If bilateral differences of FA values were statistically significant (P < 0.05), the measurement values were directly compared.  Results  1) There was no significant difference of FA values in bilateral symmetric white matter and temporal stem among AD, aMCI and NC groups (P > 0.05, for all). 2) There was significant difference of FA values in anterior commissure, uncinate fasciculus and inferior occipitofrontal fasciculus between AD and aMCI groups (P < 0.05, for all). 3) There was significant difference of FA values in anterior commissure, uncinate fasciculus, inferior occipitofrontal fasciculus, anterior frontal and parietal lobes between AD and NC groups (P < 0.05, for all). 4) There was no significant difference of FA values in anterior commissure, uncinate fasciculus, inferior occipitofrontal fasciculus, anterior frontal lobe between aMCI and NC groups (P > 0.05, for all).  Conclusions  The significant difference of FA values in temporal stem among AD, aMCI and NC groups suggests that temporal stem fiber bundles are of great significance in the white matter damage of AD, and DTI is helpful for the differential diagnosis of AD, aMCI and NC. The abnormal changes of FA values in anterior commissure, uncinate fasciculus, inferior occipitofrontal fasciculus, anterior frontal and parietal lobes are of great diagnostic value in AD.

Key words: Alzheimer disease, Cognition disorders, Memory disorders, Temporal lobe, Magnetic resonance imaging