NODDI技术对认知障碍患者海马及海马旁回微观结构的研究

目的利用神经突方向离散度和密度成像(NODDI)技术对微观结构的敏感性和特异性探究遗忘型轻度认知障碍(aMCI)和阿尔茨海默病(AD)双侧海马及海马旁回微观结构改变,为探究AD病理机制提供更多信息,并以此检验NODDI技术的临床价值。方法根据纳入标准和排除标准,选取aMCI患者17例(aMCI组)、AD患者20例(AD组),健康志愿者21例(NC组)进行NODDI扫描,利用MRIcro软件测量各组双侧海马及海马旁回神经突密度指数(NDI)、神经突方向离散度指数(ODI)、各向同性水分子体积分数(Viso),三组间各参数利用单因素方差分析比较差异性,对于有差异的参数,采用spearman相关分析差异参数与简易智能状态检查量表(MMSE)评分和蒙特利尔认知评估量表(MoCA)评分的相关性,获取相关系数r。结果双侧海马及海马旁回NDI值和ODI值均有不同程度的降低(P<0.05),Viso值有不同程度的增加(P<0.05),组间两两比较发现AD组和aMCI组只有双侧海马的Viso值差异有统计学意义(P<0.001)。相关性分析可知,NDI值和ODI值与MMSE评分和MoCA评分呈正相关,而Viso值与MMSE评分和MoCA评分呈负相关,而且相较于其他参数,Viso值的相关系数最高。结论NODDI技术很好的量化分析了不同阶段认知障碍患者海马及海马旁回微观结构的变化,证实海马及海马旁回对于海马记忆系统具有同等重要性,为探索AD的病理机制提供了更多的数据支撑。同时,NODDI技术对认知评价具有很好的临床价值,尤其是双侧海马的Viso值,有可能成为可靠的参考指标。     

轻度认知障碍患者海马的磁共振扩散峰度成像研究

目的 应用磁共振扩散峰度成像(DKI)研究轻度认知功能障碍(MCI)患者及正常老年人海马的差异.方法 搜集23例MCI患者为病例组(MCI组),23名健康志愿者为正常对照组(HC组),分别测量双侧海马的平均峰度(MK)值、轴向峰度(Ka)值、径向峰度(Kr)值、各向异性分数(FA)值、平均扩散(MD)值、轴向扩散(Da)以及径向扩散(Dr)值,使用两独立样本t检验对两组间所测DKI各参数进行分析;使用受试者工作特征曲线(ROC)曲线下面积(AUC)评价上述各参数值诊断MCI的能力;使用Pearson相关性分析对上述海马的DKI各参数值与MMSE评分的相关性进行分析.结果 与HC组相比,MCI组双侧海马的MK值、Kr值、FA值、Da值、Dr值减低,差异具有统计学意义(P＜0.05),双侧海马的MD值增加,差异具有统计学意义(P＜0.05),双侧海马的Ka值比较差异无统计学意义(P＞0.05);ROC曲线显示,左侧海马MD值的AUC最大,为0.765;Pearson相关性分析结果,双侧海马的MK值、Kr值、FA值、MD值、Da值、Dr值与简易精神状态检查量表(MMSE)评分均具有相关性(P＜0.05),海马的Ka值与MMSE评分无相关性(P＞0.05).结论 DKI技术能够敏感地探测到MCI患者海马的变化,为MCI患者和正常对照者的鉴别提供有效的影像学方法.     

MCI患者数字推理能力的海马fMRI研究

目的:比较轻度认知功能障碍(MCI)患者和正常对照在完成高级认知任务(数字推理)时海马的BOLD信号的差异,探讨MCI患者海马功能的改变和基于BOLD功能磁共振成像诊断MCI的方法.方法:使用Siemens 3.0T磁共振扫描仪对9例MCI患者和13例正常对照在完成两种数列完形任务(规则归纳和规则应用)时进行功能像扫描,并对海马区BOLD信号进行ROI分析.结果:不论是在规则归纳任务还是在规则应用任务中,MCI患者双侧海马的激活强度均低于正常对照组.结论:MCI患者在完成数字推理任务时海马激活强度的减低对于MCI的早期诊断有重要的参考价值.     

轻度认知损害海马结MR定量与波谱的研究

目的 探讨MRI海马体积测定和氢质子磁共振波谱(1HMRS)对遗忘型轻度认知功能障碍(aMCI)和Alzheimer病(AD)的诊断和鉴别诊断的作用.方法 对入选的12例aMCI患者、12例AD患者和12例性别、年龄、文化程度相匹配健康对照组(NC)的双侧内侧颞叶和左后扣带回1HMRS进行分析,比较各组间N-乙酰天门冬氨酸(NAA)/ 肌酸(Cr),胆碱(Cho)/ 肌酸(Cr),肌醇(mI)/ 肌酸(Cr),N-乙酰天门冬氨酸(NAA)/ 肌醇(mI)差别.海马体积测定是在常规扫描的基础上对海马进行定位,并行垂直于海马长轴的斜冠状IRPDWITfl3D序列扫描:TI 1 100 ms ;TR 1 830 ms ; TE 3.93 ms ; 采集次数 3 次、层厚 1.2 mm、FOV 25 cm、矩阵 256×256,无间隔连续扫描.扫描范围包括杏仁核前部及侧脑室后角.结果 左内侧颞叶aMCI和AD组的NAA/Cr均明显低于NC组 (P<0.05),AD组与aMCI组比较无显著性改变(P>0.05);aMCI组和AD组的NAA/mI 低于NC组(P<0.05),AD组与aMCI组比较无显著变化(P>0.05).右内侧颞叶AD组和aMCI的NAA/mI 显著低于 NC 组 (P<0.05).aMCI、AD组和 NC组左扣带回后部NAA/Cr、Cho/Cr、mI/Cr及NAA/mI差异均无显著变化.3组双侧校正后海马体积比较,NC、aMCI组和AD组两侧海马体积比较差异有显著改变(P<0.05),NC组和aMCI组的两侧海马体积差异无显著改变(P>0.05); AD组与aMCI组各自的左右侧海马体积与3个部位的代谢物比值无明显相关.结论 海马体积测定在鉴别诊断aMCI和AD有重要价值,1H-MRS诊断及鉴别aMCI和NC有相对高的敏感性.     

阿尔茨海默病及轻度认知障碍PET/MR研究进展

阿尔茨海默病(AD)是一种进行性发展的神经退行性疾病,轻度认知障碍(MCI)被认为正常衰老和AD之间的过渡阶段。目前AD的治疗主要是延缓病情和预防并发症,因此早期诊断与干预尤为重要。新型大型影像设备PET/MR实现了对AD及MCI代谢、结构以及功能的多模态研究融合。本文就目前PET/MR在AD及MCI的研究现状做一综述。     

轻度认知功能障碍及阿尔茨海默病脑白质的MR扩散张量成像研究

目的 应用MR DTI方法评价轻度认知功能障碍(MCI)及阿尔茨海默病(AD)脑白质微观结构完格性,进一步探讨脑白质异常与认知功能损害之间的关系.方法 选取9例遗忘型MCI(MCI组)、15例可能AD(AD组)和11名年龄匹配的正常老年人(NC组),对常规腩部MRI脑白质表现正常的部位进行DTI扫描,测量不同脑区的各向异性指数(FA)及平均扩散率(MD),应用单因素方差分析对3组相应区域进行组间比较,并对所有被试DTI指数与临床认知评价量表积分进行相关性检验.结果 MCI患者顶叶、半卵圆中心、后扣带回、海马旁回、颞叶、额叶FA值分别为0.31±0.03、0.39±0.03、0.62±0.05、0.59±0.05、0.47±0.08、0.32±0.04,MD值分别为(899±30)×10-6、(782±53)×10-6、(732±45)×10-6、(806±38)×10-6、(772±55)×10-6、(792±35)×10-6mm2/s.AD患者相应部位FA值分别为0.28±0.04、0.37±0.03、0.55±0.06、0.52±0.05、0.40±0.05、0.27±0.04,MD值分别为(912±37)×10-6、(800±67)×10-6、(762±46)×10-6、(874±57)×10-6、(822±55)×10-6、(822±39)×10-6mm2/s.NC组FA值分别为0.36±0.03、0.43±0.05、0.64±0.05、0.60±0.05、0.52±0.05、0.33±0.03,MD值分别为(866±37)×10-6、(754±54)×10-6、(718±32)×10-6、(810±39)×10-6、(755±48)×10-6、(785±23)×10-6mm2/s.与NC组对比,MCI组的顶叶FA值明显下降(P<0.01),AD组顶叶、半卵圆中心FA值亦明显减低(P<0.01),且后扣带回、海马旁回及颞叶、额叶脑白质FA值及相应MD值差异有统计学意义(P<0.05),同时这些区域DTI指数与临床认知评价量表积分具有相关性(P<0.05).结论 MR DTI能够探测AD及MCI患者脑白质微观结构异常,顶叶脑白质FA值的异常在认知功能损害的早期即已发生,该脑区白质异常改变及区域性失联络在痴呆进程中可能起到重要作用.     

酰胺质子转移磁共振成像在阿尔茨海默病和轻度认知障碍中的应用

目的 探讨3D酰胺质子转移(APT)磁共振成像诊断阿尔茨海默病(AD)和轻度认知障碍(MCI)的可行性。资料与方法 前瞻性收集2020年9月—2022年1月在北京医院接受治疗的AD患者29例、MCI患者19例和性别、年龄匹配的正常对照组20例进行头部3D APT磁共振成像,计算双侧额叶灰质和海马的3.5 ppm处酰胺质子不对称磁化转移率(MTR_asym),比较不同脑区3组间MTR_asym(3.5 ppm)的差异,对有差异的脑区进行两两比较(Bonferroni校正)。分析双侧额叶灰质和海马的MTR_asym(3.5 ppm)与简易精神状态量表(MMSE)评分的相关性。对组间有差异的APT参数进行受试者工作特征曲线分析,评估其对AD的诊断效能。结果 左侧额叶灰质MTR_asym(3.5 ppm)在3组间差异有统计学意义(F=4.18,P=0.02),右侧额叶灰质和双侧海马3组间MTR_asym(3.5 ppm)差异无统计学意义(F=1.37、0.49、0.50,P均>0.05),...     

海马体积测量联合 MMSE 评分在认知障碍中的应用

目的：探讨测量海马体积(HV)联合简易智力状况检查量表(MMSE)评分评估不同程度认知功能障碍的价值。方法收集阿尔茨海默病(AD)患者、轻度认知障碍(MCI)患者、正常对照(NC)各30例,应用西门子 MRI 行 HV 测量,综合分析3组患者标准化后的 HV、MMSE 评分。结果与 MCI、NC 组比较,AD 组总 HV、左右侧均减小,差别有统计学意义(P 值均<0.05);MCI 与 NC 2组之间 HV 无显著差异;分析3组患者的 MMSE 评分,AD 组分值均小于 MCI、NC 组,差别有统计学意义(P 值均<0.05),MMSE 评分在MCI 与 NC 2组间无差别。结论HV 测量联合 MMSE 评分,有助于为 AD 患者诊断提供有价值的信息,而在 MCI 中的诊断灵敏度不高。     

海马亚区T2信号对轻度认知损害治疗前后的评价研究

目的 探讨海马亚区MRI T2信号强度对轻度认知损害(MCI)患者盐酸多奈哌齐治疗前后疗效评估的价值.方法 收集MCI患者40例并随机均分为2组(治疗组及对照组).治疗组采用盐酸多奈哌齐治疗,对照组采用安慰剂治疗,治疗期为3个月.所有受试者治疗前后均行快速自旋回波T2序列,并在工作站勾画海马各亚区,测量其MRI T2信号强度并标准化,同时分析治疗组治疗前后海马各亚区MRI T2信号强度与简易精神状态检查(MMSE)评分的相关性.结果 治疗前,与对照组比较,治疗组双侧海马各亚区MRI T2信号强度差异无统计学意义.治疗后,治疗组双侧海马头部MRI T2信号强度较对照组显著降低,差异有统计学意义(P<0.05),而双侧体尾部MRI T2信号强度在治疗后差异无统计学意义.治疗组MMSE评分与治疗前后双侧海马头部MRI T2信号强度均呈负相关(P<0.05).结论 双侧海马头部MRI T2信号强度可有效评估MCI治疗后效果,可作为MCI早期诊疗有价值的辅助指标.     

阿尔茨海默病与轻度认知功能障碍的磁共振成像研究进展

本文综述了近些年阿尔茨海默病与轻度认知功能损害在磁共振成像脑结构测量、弥散成像、波谱成像及功能成像等方面的研究,旨在对其早期临床诊断及治疗提供参考。     

轻度认知障碍患者海马的影像学研究进展

海马是学习记忆相关的重要脑区,其结构、功能的异常与轻度认知障碍（MCI）的发生发展密切相关。MRI、PET等影像学检查手段能提供海马的结构、功能与葡萄糖代谢等指标,能对早期筛查和诊断MCI提供更多的影像学支持。笔者主要综述了遗忘型MCI患者海马结构、海马的功能连接及海马葡萄糖代谢的影像学研究进展,以期发现更加敏感的影像学指标用于MCI的诊断。     

Medial temporal lobe atrophy in Alzheimer's disease/mild cognitive impairment with depression

Objective:

Depression is common in patients with Alzheimer''s disease (AD) and mild cognitive impairment (MCI). Patients with depression have an earlier onset and rapid progression of cognitive decline. Medial temporal lobe atrophy (MTA) is common in AD and MCI, and some degree of atrophy is found in almost all patients. In the present study, an attempt was made to know if MTA is more common in patients with AD/MCI with depression than those without it.

Methods:

Patients reporting to the outpatient department of a neurology centre of a tertiary care hospital were recruited for the present study. After initial general physical and neurological examination, they were evaluated using National Institute of Neurological and Communicative Disorders and Stroke and Related Disorders Association criteria for diagnosis of AD. Clinical Dementia rating scale was used for the diagnosis of MCI. Cornell scale for depression in dementia (CSDD) was used.

Results:

We found 20 cases with depression as per CSDD out of a sample of 37 patients (male:female = 30:7). There were 26 patients with AD and 11 with MCI. The mean age of all patients was 72.33 ± 6.45 years. The mean mini mental status examination score was 19.00 ± 6.73. The mean time since diagnosis was 4.19 ± 3.26 years. The mean Scheltens visual rating scale score for right MTA was 2.08 ± 0.95 and was 2.05 ± 0.94 for the left. Both scores did not differ statistically when analyzed using paired t-test (p > 0.05). However, difference in those with depression (2.36 ± 0.95) from those without depression (1.60 ± 0.74) was significant (p < 0.05).

Conclusion:

MTA scores were higher in those with AD/MCI with depression than those without it.Depression¹ is common in patients with Alzheimer''s disease (AD) and mild cognitive impairment (MCI). Relationship between depression and cognitive decline is a complex one, and depression is both an aetiological risk factor² and comorbidity for dementia.³ Incidence and prevalence of depressive symptoms in MCI range from 15% in population-based studies to 44% in hospital-based studies.⁴ Likewise, up to two-thirds of patients with AD have been reported to have depression.⁵ Because in many studies, depression has been seen to be an early manifestation of AD, it has been suggested that it may represent a continuum⁴ from depression to MCI to AD (late-life depression → MCI → AD). Two recent meta-analyses have found that a history of depression approximately doubles an individual''s risk for subsequent dementia in general and AD in particular.⁶ Depression is known to be neurotoxic to medial temporal lobe structures and can contribute to their atrophy.^7–9 Atrophy is more so, when depression is severe or recurrent⁷ and medial temporal lobe atrophy (MTA) has a temporal association with depression.⁹ Continued treatment of depression has been shown to protect the hippocampus from the ill effects of depression.¹⁰ Although volumetric method could be a preferred mode of measuring the hippocampal volume in AD, qualitative rating of MTA is a good alternative.¹¹ Visual rating of the hippocampal volume^12–14 can be carried out using Scheltens et al¹⁵ rating scale that is based on the width of the choroid fissure, the width of the temporal horn and the height of hippocampal formation and is a quantitative scale.     

Dynamic balance deficit and the neural network in Alzheimer's disease and mild cognitive impairment

BackgroundPatients with Alzheimer’s disease (AD) and mild cognitive impairment (MCI) exhibit balance deficits. Although only a few studies have evaluated the relationship between the brain images and balance indices. In this study, we measured balance indices, including the index of postural stability (IPS) and assessed the relationship between the brain images and their clinical motor and cognitive functional features.MethodsThe study included patients with MCI (N = 14) and patients with AD (N = 19). The primary outcome was IPS under a visual block condition and/or a proprioception block condition. In addition, 9 MCI and 8 AD patients underwent a 1.5-Tesla (1.5-T) Magnetic Resonance Imaging (MRI) scan, and the relationships between the MRI parameters and the balance indices were evaluated.ResultsThe IPS score was significantly lower in the AD group than the MCI group, but only under the closed eyes/hard surface condition. In terms of MRI, there was a significant positive correlation between the IPS and the regional betweenness centrality in the left hippocampal region.ConclusionsThe finding of a significantly lower IPS score under the closed eyes/hard surface condition in AD than in MCI cases suggests that the vestibular and/or proprioceptive systems were more severely impaired in AD than MCI cases. The results suggest that a dynamic balance disturbance due to deficits of the vestibular hippocampal pathway may be a useful marker for the diagnosis of MCI and detection of disease progression from MCI to AD.     

Gait assessment in mild cognitive impairment and Alzheimer's disease: the effect of dual-task challenges across the cognitive spectrum

Gait impairment is a prominent falls risk factor and a prevalent feature among older adults with cognitive impairment. However, there is a lack of comparative studies on gait performance and fall risk covering the continuum from normal cognition through mild cognitive impairment (MCI) to Alzheimer's disease (AD). We evaluated gait performance and the response to dual-task challenges in older adults with AD, MCI and normal cognition without a history of falls. We hypothesized that, in older people without history of falls, gait performance will deteriorate across the cognitive spectrum with changes being more evident under dual-tasking. Gait was assessed using an electronic walkway under single and three dual-tasks conditions. Gait velocity and stride time variability were not significantly different between the three groups under the single-task condition. By contrast, significant differences of decreasing velocity (p<0.0001), increasing stride time (p=0.0057) and increasing stride time variability (p=0.0037) were found under dual-task testing for people with MCI and AD. Less automatic and more complex dual-task tests, such as naming animals and serial subtraction by sevens from 100, created the greatest deterioration of gait performance. Gait changes under dual-tasking for the MCI and AD groups were statistically different from the cognitively normal controls. Dual-task assessment exposed gait impairments not obvious under a single-task test condition and may facilitate falls risk identification in cognitively impaired persons without a history of falls.     

Proton magnetic resonance spectroscopy of the hippocampus in patients with mild cognitive impairment: a pilot study

OBJECTIVE: To assess the brain metabolites in the hippocampus of patients with mild cognitive impairment (MCI) using proton magnetic resonance spectroscopy at 0.5 T. METHODS: Absolute concentrations and ratios to creatine of N-acetyl aspartate, myoinositol, glutamate + glutamine, and choline were measured in the right and left hippocampus of 5 MCI patients and 5 control subjects. RESULTS: In MCI subjects, reduced N-acetyl aspartate was found in the right hippocampus (P = 0.01), and increased myoinositol was found in the left hippocampus (P = 0.02). Myoinositol/N-acetyl aspartate ratios were higher in the right (P = 0.03) and left (P = 0.01) hippocampus of MCI subjects. No significant difference in the concentration of glutamate + glutamine was observed between the control and MCI groups. CONCLUSIONS: An increase in myoinositol and a decrease in N-acetyl aspartate may be observed in the preclinical stages of dementia. Ratio measurements of these metabolites may serve as a biomarker for MCI.     

DTI studies in patients with Alzheimer's disease,mild cognitive impairment,or normal cognition with evaluation of the intrinsic background gradients

Introduction  

The objective of the study was to explore the impact of the background gradients on diffusion tensor (DT) magnetic resonance imaging (DT-MRI) in patients with Alzheimer's disease (AD), mild cognitive impairment (MCI), or cognitively normal (CN) aging.     

遗忘型轻度认知障碍的脑白质纤维束成像研究

目的：应用纤维束成像术研究遗忘型轻度认知功能障碍(aMCI)患者脑白质细微结构的改变。方法对30例经临床诊断的 aMCI 患者和31例正常对照(NC)组行扩散张量成像,用 dTV II 软件重建出扣带束、胼胝体、钩状束及下枕额束,并沿着白质束测量部分各向异性(FA)值。对比分析 aMCI 组与 NC 组各白质束的 FA 值,并将 aMCI 组的 FA 值与简易智能精神状态检查量表(MMSE)评分进行相关性分析。结果①aMCI 组的两侧扣带束、两侧钩状束及胼胝体 FA 值明显低于 NC 组,差异有统计学意义;左侧下枕额束 FA 值低于 NC 组,但差异无统计学意义。②右侧扣带束的 FA 值与 MMSE 评分呈正相关。结论aMCI 患者扣带束、钩状束及胼胝体 FA 值的异常改变,提示在阿尔茨海默病(AD)的前驱阶段存在与记忆相关的脑白质束的微损害,纤维束成像(tractography)技术对脑白质的早期损害具有很高的敏感性。