基于自动分割技术的轻度阿尔茨海默病皮层下灰质结构MR扩散张量成像分析  

Application of automatic segmentation tool in MR diffusion imaging analysis of subcortical gray structures in mild Alzheimer＇s disease

作　　者：李亚迪[1] 董海波[1] 谢国民[2] 张玲君[3] 

机构地区：[1]宁波市医疗中心李惠利医院放射科,浙江宁波315040 [2]宁波市医疗中心李惠利医院神经内科,浙江宁波315040 [3]宁波大学科学技术学院人文分院

出　　处：《实用放射学杂志》2012年第11期1669-1673,共5页Journal of Practical Radiology

基　　金：宁波市社会发展科研项目（2011C50012）.

摘　　要：目的研究发现阿尔茨海默病患者除海马外多个皮层下灰质结构也存在纤维缠结等病理改变。本文目的在于对轻度阿尔茨海默病（Alzheimer’S disease，AD）患者皮层下灰质结构进行自动分割，研究这些灰质结构平均扩散率（mean diffusivity,MD）改变特点及其在疾病诊断中的应用价值。方法选取29例轻度AD患者和30例正常老年人（正常对照组），对全脑进行1．5T磁共振快速扰相位梯度回波反转恢复脉冲序列及单次激发自旋回波的平面回波成像序列扫描。采用FSL软件的FIRST工具对被试者3DT1图像内皮层下灰质结构（包括海马、杏仁核、伏隔核、尾状核、壳核、苍白球、丘脑）进行精确分割后变形至扩散空间。2组各皮层下灰质结构平均MD值进行双样本Mann-Whitney U检验，患者组各灰质结构平均MD值分别与简易智能精神状态检查量表（mini—mental state examination，MMSE）评分进行偏相关分析，最后采用2项逻辑回归分析与ROC曲线研究这些灰质结构平均MD值在诊断轻度AD中的意义。结果与正常对照组比较，轻度AD组双侧海马、右侧苍白球、右侧尾状核及右侧丘脑平均MD值较正常显著性升高。轻度AD组右侧苍白球、右侧海马的平均MD值分别与MMSE评分具有相关性。2项逻辑回归分析最终进入模型的协变量为双侧海马及苍白球平均MD值，准确率为90．2％，受试者工作特征曲线（receiver operating characteristic curve,ROC曲线）示曲线下面积（area under the curve，AUC）为0．978，诊断点的敏感度为87．5％，特异度为100％。结论除了海马以外，轻度AD患者其他皮层下灰质结构也出现了病理改变，并可能参与了患者认知功能损害的病理机制。MR扩散成像分析皮层下灰质结构有助于轻度AD的诊断。Objective Previous studies observed that neurofibrillary tangle existed not only in hippocampus but also in other subcortical gray matter regions. The purpose of this study was to investigate the changes of mean diffusivity within subcortical gray matter regions in patients with mild Alzheimer＇s disease using an automatic segmentation tool. Methods Twenty-nine patients with mild AD and 30 normal aging volunteers were scanned using 3DFSPGRIR and SE-EPI sequence on a 1.5T MR system. The subcorti- cal gray matter structures were segmented using FIRST tool in FSL. The mean values of mean diffusivity（ MD）in each region were compared between AD group and control group using two-sample Mann-Whitney U test. The correlation between mean MD value in each region and MMSE scores were evaluated using partial correlation analysis. Binary logistic regression analysis and ROC curve were applied to assess the diagnostic significance of mean MD value in each region. Results Compared with control group,the mean MD values of bilateral hippocampi, pallidums, right thalamus and caudate in mild AD group were significantly increased （P〈0.05）. The mean MD values of right hippocampus and pallidum were correlated with MMSE scores. The mean MD values of bilateral hipp-ocampi and pallidums were analyzed in the final model of binary logistic regression. The accuracy was 90.2%. The area under the curve of receiver operating characteristic（ ROC ） curve was 0. 978. In the cut-off point of maximal value of Youden index, the sensitivity was 87.5 % and the specificity was 100 %. Conclusion Besides hippocampus AD pathological damage take place in other subcortical gray matter structures ,which might be related to the pathological mechanism of cognitive impairment. The application of MR diffusion imaging of subcortical gray matter could be a helpful tool in the diagnosis of mild AD.

关 键 词：阿尔茨海默病 扩散张量成像 磁共振成像 

分 类 号：R742[医药卫生—神经病学与精神病学] R445.2[医药卫生—临床医学]