Abstract:

Objective To observe the application of fMRI in detecting the default mode network (DMN) of patients with carotid artery stenosis and cognitive impairment. In the combination with neuropsychological scores, to explore the relationship between DMN and cognitive function under hypoperfusion. Methods A sample of 32 individuals, who went to Beijing Tiantan Hospital affiliated to Capital Medical University for treatment since June 2017 to December 2018, have been selected for this research. Among them 16 patients were confirmed by DSA with severe stenosis (stenosis rate ≥ 70%) of unilateral internal carotid artery (ICA); while the other 16 were healthy people as normal controls. The neuropsychological tests [Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA)] and blood oxygen level-dependent functional MRI (BOLD-fMRI) were performed to all the individuals. Furthermore, the function imaging was performed to develop a brain network model and to compare the differences of functional connectivity (FC) between 2 groups. Results The MoCA score in ICA stenosis group was lower than that in normal control group [(21.19 ± 4.00) score vs. (27.94 ± 2.00) score; t = 2.609, P = 0.048], indicating there was cognitive impairment in some degree in ICA stenosis. The significant FC in ICA stenosis group and normal control group were widely distributed between the frontal lobe and the occipital lobe, within the hemisphere and between both hemispheres. The FC of ICA stenosis group was significantly weaker than that of normal control group. The functional reduction between both hemispheres was indicated in the regions including the right frontal lobe, left parietal lobe and left temporal lobe, the lower margin of right parietal lobe and left amygdala. In the hemisphere, the FC was weaken between the frontal and prefrontal lobes. A specific enhancement in the function of the local brain region was also shown in ICA stenosis group. Conclusions Regarding the patients with carotid artery stenosis and cognitive impairment, the DMN has changed. The enhancement or attenuation of the FC within the hemisphere and between both hemispheres were reflected on fMRI. This may be related to the local functional changes under long-term hypoperfusion.

Key words: Carotid stenosis, Cognition disorders, Magnetic resonance imaging, Neuropsychological tests

摘要：

目的 利用fMRI对颈动脉狭窄伴认知功能障碍患者的脑默认网络进行观察分析，结合神经心理学测验量表，探讨低灌注状态下脑默认网络连接与认知功能二者之间的联系。方法 共纳入2017 年 6 月至 2018 年 12 月经 DSA 证实的 16 例单侧症状性颈内动脉重度狭窄（狭窄率 ≥ 70%）患者为研究对象，分别采用简易智能状态检查量表（MMSE）和蒙特利尔认知评价量表（MoCA）进行认知功能评价，并基于血氧水平依赖性功能磁共振成像建立脑网络模型，比较颈动脉狭窄组与正常对照组受试者功能连接的差异性。结果 颈动脉狭窄组患者 MoCA 评分低于正常对照组［（21.19 ± 4.00）分对（27.94 ±2.00）分；t = 2.609，P = 0.048］，提示存在一定程度的认知损害。颈动脉狭窄组和正常对照组受试者组内显著功能连接均呈现额叶至枕叶、大脑半球内与双侧大脑半球间广泛分布，但颈动脉狭窄组患者功能连接明显减弱。其中，双侧大脑半球间功能连接减弱以右侧额叶与左侧顶叶、左侧颞叶之间，右侧顶下缘角回与左侧杏仁核之间，双侧楔叶间等脑区为主；大脑半球内则表现为双侧内额叶和前额叶间功能连接减弱。颈动脉狭窄组患者尚可见局部脑区功能连接特异性增强。结论 颈动脉狭窄伴认知功能障碍患者在静息状态下脑默认网络可发生改变，在fMRI上呈现大脑半球内及双侧大脑半球间功能连接增强或减弱，可能与长期低灌注引起的局部脑功能改变有关。

关键词: 颈动脉狭窄, 认知障碍, 磁共振成像, 神经心理学测验