磁敏感加权成像检测脑内铁沉积在老年认知障碍中的应用价值

Value of susceptibility-weighted MRI in determining brain iron deposition for elderly patients with mild cognitive impairment

摘要:

目的 应用磁敏感加权成像（SWI）分析老年人轻度认知功能障碍（MCI）和阿尔茨海默病（AD）患者脑内铁沉积的特点及其与简易精神状态检查量表（MMSE）评分变化的相关性，评估脑内铁含量增加在预测MCI向AD转化中的价值。方法 选取2009年11月至2013年1月入院于上海交通大学附属上海市第六人民医院老年科的MCI患者22例，AD患者20例及认知功能正常的老年人18例，行常规磁共振成像（MRI）及颅脑SWI检查，使用校正相位图计算出相应的角弧度值，量化海马与尾状核头的铁沉积。采用方差分析进行组间比较；角弧度值与MMSE评分的相关性分析采用Pearson相关性分析方法。MCI组患者随访1年，根据再次MMSE评分结果分为AD转化组和非AD转化组。比较随访前后两组间角弧度值的变化量有无差异。结果 MCI组左侧海马、左侧尾状核头的角弧度值与对照组比较，差异有统计学意义（P＜0.05）；AD组双侧海马、左侧尾状核头的角弧度值与对照组比较，差异有统计学意义（P＜0.05）。双侧海马角弧度值与MMSE评分相关。随访1年后，MCI组22例患者中有5例进展为AD（22.7%），进展为AD的5例患者较稳定于MCI组的17例患者左侧海马角弧度值增加更多（P＜0.05）。结论 脑内局灶性铁沉积增加与认知功能减退有关；左侧海马铁沉积的异常增加可能是预测MCI向AD进展的敏感指标。

Abstract:

Objective To investigate the features of brain iron deposition in elderly patients with mild cognitive impairment (MCI) or with Alzheimer’s disease (AD) by using susceptibility-weighted imaging (SWI), analyze their correlation with the scores of Mini-Mental State Examination (MMSE), and assess the value of iron concentration increase in the conversion of MCI to AD. Methods A total of 18 normal control subjects, 22 MCI patients and 20 AD patients admitted to the Sixth People’s Hospital from November 2009 to January 2013 were included in this study. All the subjects underwent conventional magnetic resonance imaging (MRI) and SWI using axial/oblique coronal sequences. Phase images were used to calculate the radian angle value and bilateral iron deposition in the hippocampus and caudate nucleus. Analysis of variance (ANOVA) was employed to make comparison among the groups, the correlation of the radian angle valne with MMSE score was tested using Pearson’s correlation. After 1 year’s follow-up, MCI patients were surveyed by MMSE again, and were divided into stable MCI group (AD converters) and progressive MCI group (non-AD converters) according to the results of MMSE. The alteration of radian angle value before and after the follow-up was compared between the 2 groups. Results There were significant differences in the radian angle values in the left hippocampus and left head of the caudate nucleus between the MCI and normal control (NC) groups (P＜0.05), and in the bilateral hippocampus and left head of caudate nucleus between the AD and NC groups (P＜0.05). Radian angle values in bilateral hippocampus were positively correlated with MMSE score. During the follow-up, 5 of these 22 MCI patients converted to AD (22.7%), and had significantly higher radian angle values in the left hippocampus than non-AD converters (P＜0.05). Conclusion Regionally excessive iron deposition in the brain is associated with cognitive deficiency. For MCI patients, abnormal enhancement of iron concentration in the left hippocampus may provide predictive information about the conversion from MCI to AD.