轻度认知障碍病人脑铁沉积的定量磁敏感图研究

Quantitative susceptibility mapping of the brain iron deposition in patients with mild cognitive impairment

目的采用定量磁敏感图研究,探讨轻度认知障碍(MCI)病人大脑铁沉积特点及其与认知功能损害之间的关系。方法招募30例MCI病人及30名健康对照志愿者,2组人群的年龄[(58.20±6.78)岁和(56.97±4.77)岁]、性别(男/女:18/12和15/15)和受教育水平[(10.47±3.14)年和(11.06±2.41)年]均匹配。采用多种量表(包括简易精神状态检查表、蒙特利尔认知评估量表、连线测试、分类词语流畅性测试、听觉词语学习测试、Rey-Osterrieth复杂图形测试和波士顿命名测试)测试受试者的认知功能,采用1.5 T MR设备采集磁敏感加权成像数据并测定海马等脑区的磁化率值。采用组间双样本t检验对量表评分进行比较,并在MCI组中对有组间差异的量表评分和磁化率值行偏相关分析。结果 MCI组总体认知功能、记忆功能和注意-执行功能水平低于对照组(P<0.05),MCI组较对照组的双侧海马的磁化率值升高[左侧(61.70±5.89)×10^(-9)和(45.83±3.86)×10^(-9),P<0.001;右侧(59.55±4.52)×10^(-9)和(45.87±3.63)×10^(-9),P<0.001],并与记忆功能水平呈负相关(P<0.05)。结论 MCI病人存在以海马为主的大脑铁沉积,海马铁沉积有可能成为预测MCI病人记忆功能下降的影像学标志。

Objective To investigate the characteristics of iron deposition and its relationship with cognitive function in mild cognitive impairment(MCI)patients using quantitative susceptibility mapping.Methods Thirty MCI patients and 30 healthy controls were recruited into the study and group-matched in terms of age(years:58.20±6.78 vs.56.97±4.77),sex(male/female:18/12 vs.15/15)and years of education(years:10.47±3.14 vs.11.06±2.41).The cognitive functions of all participants were evaluated with neuropsychological tests,including mini-mental state examination,Montreal cognitive assessment,trail making test,category verbal fluency test,auditory verbal learning test,Rey-Osterrieth complex figure and Boston naming test.The susceptibility weighted imaging data of all participants were collected using 1.5 T MR scanner to assess the susceptibility values of brain areas including hippocampus.Two-sample t test was applied to conduct the inter-group comparisons and partial correlation analyses were used to explore the relationships between aberrant neuropsychological tests scores and susceptibility values in the MCI group.Results Compared with the healthy controls,MCI patients showed significant decline in general cognition,memory and attention-executive function,and significant elevated susceptibility values in the hippocampi[left(61.70±5.89)×10-9 vs.(45.83±3.86)×10-9,P<0.001;right(59.55±4.52)×10-9 vs.(45.87±3.63)×10-9,P<0.001].The susceptibility values in the hippocampi were negatively related to memory function in the MCI group(P<0.05).Conclusion MCI patients exhibit iron deposition in hippocampi.The iron deposition in hippocampi may be a biomarker to predict the memory dysfunction in MCI patients.