磁共振弥散张量成像对预测皮质下缺血性血管性痴呆患者认知功能障碍的价值

目的应用磁共振弥散张量成像(DTI)技术,探讨皮质下缺血性血管性痴呆(SIVD)患者不同联络纤维感兴趣区弥散张量参数改变与认知功能的关系。方法对60例SIVD患者和40例年龄匹配的非痴呆对照者,采用测定感兴趣区弥散张量参数的方法,比较其纤维束完整性差异及与神经心理学量表的关系。结果 (1)与对照组比较,SIVD组双侧下额枕束、双侧扣带束、左侧上纵束和胼胝体膝部的FA值显著下降及ADC值显著升高;(2)双侧额叶前部皮质下白质FA值与MMSE及Mo CA评分呈明显正相关;(3)双侧海马区、双侧扣带束的FA值与MMSE评分呈明显正相关。结论不同脑区的弥散张量参数变化特点有助于SIVD患者认知功能障碍的早期预测。     

皮质下缺血性血管性痴呆患者认知功能与脑白质弥散张量成像的关系

目的探讨皮质下缺血性血管性痴呆(SIVD)患者认知功能与脑白质弥散张量成像(DTI)的关系。方法采用MMSE、蒙特利尔认知测评量表(Mo CA)及临床痴呆量表(CDR)评价60例SIVD患者(SIVD组)和45名正常对照者(正常对照组)。应用DTI技术测量患者脑白质不同感兴趣区(ROI)各向异性分数(FA)和表观弥散系数(ADC)。SIVD组用常规头颅MRI采用年龄相关白质改变(ARWMC)评分方法对侧脑室周围脑白质高信号严重程度进行评分。结果与SIVD组比较,正常对照组MMSE及Mo CA评分显著增高,CDR评分显著降低(均P0.01)。与正常对照组比较,SIVD组双侧额叶前部、双侧侧脑室前角区及后角区的FA值显著下降,ADC值显著升高(P0.05~0.01)。其余各区FA及ADC值差异无统计学意义。SIVD组ARWMC评分为1分11例(18.3%),2分31例(51.7%),3分18例(30.0%)。正常对照组中5人(11.1%)为1分。Spearman相关性分析显示,SIVD组ARWMC评分与双侧侧脑室前角区及后角区FA值呈负相关(r=-0.912,P0.01),与ADC值呈正相关(r=0.891,P0.01)。双侧额叶前部皮质下白质及海马区FA值与MMSE及Mo CA评分呈正相关(P0.05~0.01)。结论 SIVD患者多个ROI的FA值降低及ADC值的增高程度,可以反映认知功能障碍的程度。     

磁共振弥散张量成像对阿尔茨海默病脑白质损害的评估及鉴别价值

目的：应用MR弥散张量成像（DTI）观察阿尔茨海默病（AD）患者脑白质纤维束完整性。方法：健康老年志愿者为对照组（NC）组、遗忘型轻度认知障碍（aMCI）组、AD组和皮质下缺血性血管性痴呆（SIVD）组各20例,行常规MRI和DTI扫描后,测定相同感兴趣区（ROI）的各向异性分数（FA）值和表观扩散系数（ADC）值进行比较。结果：与NC组比较, AD组前额叶、颞叶、海马等部位FA值降低,颞叶、海马等部位ADC值升高（P〈0.05）;aMCI组仅扣带束FA值降低,与AD组比差异有统计学意义（P〈0.05）;SIVD组下额枕束等部位FA值下降,ADC值升高,与AD组比较差异有统计学意义（P〈0.05）。结论：DTI可以用来评估白质纤维束完整性,AD组白质损害甚于aMCI患者;扣带束FA值可以作为aMCI患者筛查的指标;根据受累部位不同可对SIVD与AD进行鉴别。     

胼胝体和扣带回弥散张量成像改变对皮质下缺血性血管性痴呆患者认知功能障碍的影响

目的应用磁共振弥散张量成像(DTI)技术,探讨皮质下缺血性血管性痴呆(SIVD)患者胼胝体和扣带回弥散张量参数改变与认知功能的关系。方法对60例SIVD患者和40例年龄匹配的非痴呆对照者,采用测定感兴趣区弥散张量参数的方法,比较其纤维束完整性差异及与MMSE的关系。结果 (1)与对照组比较,SIVD组胼胝体膝部、双侧扣带回的FA值显著下降及ADC值显著升高,而胼胝体压部的FA值和ADC值无显著性差异。(2)胼胝体膝部、双侧扣带回的FA值与MMSE评分呈明显正相关。结论胼胝体和扣带回弥散张量改变有助于SIVD患者认知功能障碍的早期预测。     

健康者三叉神经磁共振扩散张量成像研究

目的 测量三叉神经桥池段的表观扩散系数(ADC)值和部分各向异性分数(FA)值,了解三叉神经桥池段各参数的特点。 方法 选择50例健康志愿者三叉神经桥池段距离脑干发出点0mm、3mm、6mm、9mm共四处,利用DTI图像与B-TFE或THRIVE图像融合成像,提高三叉神经桥池段显示的空间分辨率,并利用该图像测量并分别记录ADC值与FA值,对所有受检者行三叉神经桥池段追踪成像。 结果 受检者左侧与右侧三叉神经桥池段的ADC值和FA值差异均无统计学意义(P＞0.05)。越靠近脑干发出点,左右两侧三叉神经桥池段的各导出量越呈现左右不对称的趋势。双侧三叉神经桥池段距脑干不同距离各位置的DTI导出量分析发现：相邻两距离间ADC值差异均有统计学意义(P＜0.05),出脑干后随距离增加ADC值逐渐升高,但行至6～9 mm间突然回转下降;FA值在0～6 mm间随距离增加而逐渐降低,且相邻两距离间差异均有统计学意义(P＜0.05),但行至6～9 mm间FA值不再有明显变化。 结论 DTI图像能够清晰分辨双侧三叉神经桥池段,可实现DTI各项导出量的测量。随着距脑干发出点距离的不同,各导出量发生有规律的变化,预示着DTI在明确区分三叉神经的中枢神经系统段、过渡段和周围神经系统段以及检出颅神经血管压迫方面的应用前景。     

精神分裂症患者全脑白质纤维弥散张量成像的初步研究

目的运用能够提示白质纤维(white matter,WM)完整性的弥散张量成像(diffusion tensor imaging,DTI)技术,探讨精神分裂症患者全脑白质纤维是否受到损害。方法对21例精神分裂症患者(患者组)和21名健康人(对照组)进行全脑DTI扫描,用SPM2(Statistical Parametric Maps,SPM)软件对图像进行处理,采用以像素为基础的分析方法(voxel-based analysis,VBA)对两组的分数各向异性(fractional anisotropy,FA)值进行组间比较。结果患者组下列脑区的FA值显著低于对照组(P<0·001):左侧额眶区和右侧额中回的白质、双侧颞下回白质、双侧顶叶内侧白质、右侧前扣带、双侧海马、双侧大脑脚、双侧岛叶、右侧放射冠和右侧小脑上脚。结论精神分裂症多个部位脑白质纤维的完整性受到破坏。     

皮质下血管性认知障碍患者弥散张量成像和脑血流量的研究

目的明确脑小血管病(cerebral small vessel disease,CSVD)患者白质完整性、脑血流量及其认知障碍之间的关系。方法连续招募严格定义的CSVD患者58例,分为无认知障碍(no cognitive impairment,NCI)11例、血管性轻度认知障碍(vascular mild cognitive impairment,VaMCI)29例和血管性痴呆(vascular dementia,VaD)18例三组,评定脑室旁(periventricular,PV)及放射冠(corona radiate,CR)白质的弥散张量成像(diffusion tensor imaging,DTI)参数,即平均弥散率(mean diffusivity,MD)和各向异性分数(fractional anisotropy,FA)。应用CT灌注(CT perfusion,CTP)成像对PV和CR区进行脑血流量(cerebral blood flow,CBF)测定。对DTI参数、CBF和认知评分进行相关性分析。结果 1三组间PV区的CBF及MD值比较,差异均有显著性(P0.01),其中MD值与CBF以及注意执行功能间均呈显著相关性(P0.01),但CBF和认知功能间未见相关性。三组间FA值比较,差异均无显著性,FA值亦未显示与CBF以及认知功能的相关性。2三组间CR区的CBF和MD、FA值比较,差异均无显著性,仅CR区MD和注意执行功能有一定相关性(P0.05),CBF与DTI参数以及认知功能间均未见相关性。结论脑室旁白质完整性的破坏是CSVD患者认知损害的重要影像学标志,且与低灌注密切相关。     

皮质下缺血性血管病患者认知功能的弥散张量磁共振研究

目的明确弥散张量成像(diffusion tensor imaging,DTI)对皮质下型血管性认知障碍的识别作用。方法42例皮质下缺血性血管病(subcortical ischemic vascular desease,SIVD)患者经过认知测试,被分为无认知障碍(no cognitive impairment,NCI)组,血管性认知障碍非痴呆(vascular cognitive impairment no dementia,VCIND)组和血管性痴呆(vascular dementia,VaD)组。分析其认知测试指标与DTI参数之间的关系。结果VCIND组、VaD组全脑白质平均弥散度(mean diffusivity,MD)分别为(0.89±0.05)×10-9m2.s-1和(0.93±0.05)×10-9m2.s-1,与NCI组(0.84±0.03)×10-9m2.s-1相比,有统计学差异(均P<0.01),VCIND组、VaD组各向异性分数(fractional anisotropy,FA)分别为(0.35±0.02)和(0.34±0.02),与NCI组(0.37±0.02)相比,亦有统计学差异(均P<0.01)。全脑白质MD与注意执行功能和记忆功能测验评分的相关系数分别为-0.538和-0.500,均P<0.01;FA值与注意执行功能和记忆功能测验评分的相关系数分别是0.439和0.411,均P<0.01。排除VaD患者后,MD与注意执行功能的相关系数为-0.401,P<0.05。结论 VCIND和VaD组的MD和FA值与NCI组有统计学差异,SIVD患者的注意执行与记忆功能与白质完整性独立相关。     

Regional differences in diffusion abnormality in cerebral white matter lesions in patients with vascular dementia of the Binswanger type and Alzheimer's disease

We investigated changes in water diffusion in the cerebral white matter of 14 patients with vascular dementia of the Binswanger type (VDBT) and ten patients with Alzheimer's disease (AD) with periventricular hyperintensity (PVH) lesions using diffusion-weighted magnetic resonance imaging (MRI) and studied the pathophysiological differences between white matter lesions found in these two conditions. Apparent diffusion coefficients (ADCs) in the anterior and posterior white matter and the genu and splenium of the corpus callosum were significantly higher in both groups of patients than in the 12 age-matched controls, and ADC values in VDBT and AD groups were almost the same. ADC ratios, defined as diffusion restricted perpendicular to the direction of nerve fibers, were also significantly higher in the patients than in the control subjects. However, there were regional differences in ADC ratios in the two conditions, with ratios in VDBT being higher in the anterior portions of the white matter but ratios in AD were higher in the posterior portions. The diffusion-weighted MRI technique may be useful in the differential diagnosis of VDBT and AD with white matter lesions.     

Dementia in Parkinson's disease: diffusion tensor imaging

OBJECTIVE: Dementia occurs frequently in patients with Parkinson's disease (PD). However, the nature of the dementing process remains controversial. We evaluated various cognitive functions in patients with PD, compared fractional anisotropy (FA) values between PD patients with and without dementia. METHODS: Thirty-seven consecutive patients with Hoehn-Yahr stage III or IV PD participated in this study. Patients were divided into two groups: (i) PD with dementia group (PDD) and (ii) PD without dementia group (PDND). There were 11 PDD and 26 PDND cases. Ten controls were also studied. RESULTS: The PDD group showed significant FA reduction in the bilateral posterior cingulate bundles compared with PDND. FA values in the left posterior cingulate bundle showed significant correlations with many cognitive parameters. INTERPRETATION: Our results showed that the posterior cingulate areas play some important roles in the dementing process in PDD. However, as the pathological processes responsible for dementia in PD patients may be multifaceted, further studies are necessary.     

Reduced frontal white matter integrity in cocaine dependence: a controlled diffusion tensor imaging study.

BACKGROUND: In vivo magnetic resonance studies have found that cocaine dependence is associated with T2 signal hyperintensities and metabolite abnormalities in cerebral white matter (WM). Functional neuroimaging studies have suggested that chronic cocaine use is primarily associated with frontal lobe deficits in regional cerebral blood flow and brain glucose metabolism levels; however, the effects of cocaine dependence, if any, on frontal WM microstructure are unknown. Thus, we sought to examine the effects of cocaine dependence on frontal WM integrity. METHODS: Diffusion tensor imaging was employed to examine the WM integrity of frontal regions at four levels: 10 mm above, 5 mm above, 0 mm above, and 5 mm below the anterior commissure-posterior commissure (AC-PC) plane. The fractional anisotropy (FA) of 12 cocaine-dependent patients and 13 age-similar control subjects was compared. RESULTS: The cocaine-dependent patients had significantly reduced FA in the frontal WM at the AC-PC plane and a trend toward reduced FA at 5 mm below the AC-PC plane, suggestive of reduced WM integrity in these regions. CONCLUSIONS: These findings were consistent with the hypothesis that cocaine dependence involves alterations in orbitofrontal connectivity, which may be involved in the decision-making deficits seen in this disorder.     

Alzheimer病患者扣带回后部损害磁共振扩散张量成像的研究

目的探讨Alzheimer病(AD)患者扣带回后部磁共振扩散张量成像(DTI)的特点及其与认知功能改变的相关性。方法对16例AD患者和12名健康老人(正常对照组)行DTI、T1Flair及T2Flari检查,测量扣带回后部各向异性分数值(FA)、平均弥散度(MD)及其λ1、λ2及λ33个特征值,分析上述诸项数值与简易精神状态检查量表(MMSE)评分之间的相关性。结果与正常对照组相比,AD组患者扣带回后部的FA值显著降低(P<0.05),而MD、λ1、λ2及λ3值明显升高(均P<0.05);FA值与MMSE评分不相关(r=-0.054,P>0.05),而MD值与MMSE评分呈显著负相关(r=-0.664,P<0.01);λ1、λ2及λ3值均与MMSE评分呈负相关(r=-0.643,r=-0.69,r=-0.654,均P<0.01)。结论AD患者表现为扣带回后部各向异性损害,且损害程度与临床认知功能评分呈负相关;这种损害反映了AD病理机制中皮质-皮质及皮质-皮质下联系的丢失;DTI可以用来监测AD疾病的进展及评价药物的临床疗效。     

White matter abnormalities in bipolar disorder: a voxel-based diffusion tensor imaging study

Objectives:  In bipolar disorder (BD), dysregulation of mood may result from white matter abnormalities that disrupt fronto-subcortical circuits. In this study, we explore such abnormalities using diffusion tensor imaging (DTI), an imaging technique capable of detecting subtle changes not visible with conventional magnetic resonance imaging (MRI), and voxel-based analysis.
Methods:  Thirty-six patients with BD, all but two receiving antidepressants or mood stabilizers, and 28 healthy controls matched for age and gender were studied. Diffusion-weighted echoplanar images (DW-EPI) were obtained using a 1.5T scanner. Voxel-based analysis was performed using SPM 2. Differences between the groups in mean diffusivity and fractional anisotropy (FA) were explored.
Results:  In the patient group, mean diffusivity was increased in the right posterior frontal and bilateral prefrontal white matter, while FA was increased in the inferior, middle temporal and middle occipital regions. The areas of increased mean diffusivity overlapped with those previously found to be abnormal using volumetric MRI and magnetization transfer imaging (MTI) in the same group of patients.
Conclusions:  White matter abnormalities, predominantly in the fronto-temporal regions, can be detected in patients with BD using DTI. The neuropathology of these abnormalities is uncertain, but neuronal and axonal loss, myelin abnormalities and alterations in axonal packing density are likely to be relevant. The neuroprotective effects of some antidepressants and mood stabilizers make it unlikely that medication effects could explain the abnormalities described here, although minor effects cannot be excluded.     

White‐matter abnormalities in attention deficit hyperactivity disorder: A diffusion tensor imaging study

Current evidence suggests that attention deficit hyperactivity disorder (ADHD) involves dysfunction in wide functional networks of brain areas associated with attention and cognition. This study examines the structural integrity of white‐matter neural pathways, which underpin these functional networks, connecting fronto‐striatal and fronto‐parietal circuits, in children with ADHD. Fifteen right‐handed 8 to 18‐year‐old males with ADHD‐combined type and 15 right‐handed, age, verbal, and performance IQ‐matched, healthy males underwent diffusion tensor imaging. A recent method of tract‐based spatial statistics was used to examine fractional anisotropy (FA) and mean diffusivity within major white‐matter pathways throughout the whole‐brain. White‐matter abnormalities were found in several distinct clusters within left fronto‐temporal regions and right parietal‐occipital regions. Specifically, participants with ADHD showed greater FA in white‐matter regions underlying inferior parietal, occipito‐parietal, inferior frontal, and inferior temporal cortex. Secondly, eigenvalue analysis suggests that the difference in FA in ADHD may relate to a lesser degree of neural branching within key white‐matter pathways. Tractography methods showed these regions to generally form part of white‐matter pathways connecting prefrontal and parieto‐occipital areas with the striatum and the cerebellum. Our findings demonstrate anomalous white‐matter development in ADHD in distinct cortical regions that have previously been shown to be dysfunctional or hypoactive in fMRI studies of ADHD. These data add to an emerging picture of abnormal development within fronto‐parietal cortical networks that may underpin the cognitive and attentional disturbances associated with ADHD. Hum Brain Mapp, 2009. © 2008 Wiley‐Liss, Inc.