Gray and white matter changes in Alzheimer's disease: a diffusion tensor imaging study

PURPOSE: To investigate microstructural changes in cortical and white matter pathways in patients with Alzheimer's disease using diffusion tensor imaging (DTI). MATERIALS AND METHODS: Measures of mean diffusivity (MD) and fractional anisotropy (FA) were compared in the brains of 13 Alzheimer's disease (AD) patients and a group of 13 aged-matched control participants employing an optimized DTI technique involving a fully automated, voxel-based morphometric (VBM) analysis. RESULTS: After rigorous control for anatomical variation and confounding partial volume effects, we found significantly elevated MD measures within the hippocampus, amygdala, and medial temporal, parietal, and frontal lobe gray matter regions in the AD participants. The largest number of pixels with increased MD was localized bilaterally, within the posterior cingulate gyrus. The FA was significantly reduced within the thalamus, parietal white matter, and posterior limbs of the internal capsule, indicating significant involvement of corticothalamic and thalamocortical radiations. CONCLUSION: This study demonstrates that rigorous VBM analysis of DTI data can be used to investigate microstructural changes in cortical, subcortical, and white matter regions in AD.     

早期阿尔茨海默病脑白质改变和认知功能损伤的相关性

目的 探讨早期阿尔茨海默病(AD)脑白质变化与认知功能改变的关系.方法 对14例早期AD患者(AD组)和18名健康老年人(ON组)在1.5 T MR扫描仪上进行扩散张量成像(DTI)扫描.在9个感兴趣区测量并比较各向异性分数(FA)和平均扩散系数((-D)).对2组研究对象进行8个标准的神经心理测试,以评价其基本认知能力状态,并对测试结果 进行比较.分析所有研究对象DTI的FA和(-D)测量结果 与神经心理测试评分的相关性.结果 与ON组相比,AD患者在胼胝体压部(分别为0.25±0.03和0.49±0.03)和后顶-颞叶(分别为0.30±0.02和0.28±0.01)FA降低(t值分别为2.481、1.991,P值均＜0.05)、在胼胝体压部D提高(t=1.751,P＜0.05).在8个神经心理行为测试中,AD患者的评分均低于ON组(t值2.803～4.691,P值均＜0.05).相关性研究结果 显示,AD患者胼胝体压部和后顶-颞叶的FA与多个神经心理测试评分呈正相关(r值0.355～0.499,P值均＜0.05),而在较分散的多个部位(-D)与多个神经心理测试评分呈负相关(r值-0.518～-0.350,P值均＜0.05).结论 在AD早期阶段,患者不仅有认知功能的改变,而且还有白质结构的变化,两者存在一定的相关性,表现为脑白质的选择区域性损害,这种损害反映了AD病理机制中皮质间联系的丢失.     

阿尔茨海默病患者脑白质束铁沉积的磁共振相位成像

目的：利用磁共振相位成像和扩散张量成像(DTI)技术,探讨阿尔茨海默病(AD)患者的脑白质束损伤与相应白质束铁沉积的相关性。方法：对25例AD患者及20例年龄相匹配的健康老年志愿者进行MR扩散张量成像及相位成像。DTI数据经后处理生成平均扩散系数(MD)和部分各向异性(FA)图,分别测量穹窿、胼胝体膝部、胼胝体压部、双...     

Diffusion abnormality in posterior cingulate fiber tracts in Alzheimer’s disease: tract-specific analysis

Purpose

The aim of this study was to determine diffusion abnormalities in the posterior cingulate fiber tracts (PCFTs) in patients with Alzheimer’s disease (AD) by diffusion tensor tractography (DTT).

Materials and methods

We studied 23 AD patients and 18 age-matched normal controls who underwent magnetic resonance imaging using diffusion tensor imaging (DTI). DTT of PCFTs was generated from DTI. Mean diffusivity (MD) and fractional anisotropy (FA) were measured in co-registered voxels along with DTT of PCFTs. Student’s t-test was used to compare results between the AD patients and normal controls.

Results

The MD in PCFTs was significantly higher in AD patients than in normal controls (P = 0.019). The FA in PCFTs was significantly lower in AD patients than in normal controls (P = 0.007).

Conclusion

The abnormal MD increase and FA decrease, which is considered to indicate a net loss of barriers that restrict water molecular motion and tissue anisotropy of white matter, is consistent with neuropathological data that demonstrate partial loss of myelin, axons, and oligodendrial cells in white matter of AD brains. Our results suggest that MD and FA reflect progression of AD-related histopathological changes in the PCFTs and may represent a useful biological index for monitoring AD.     

Evaluation of white matter damage in patients with Alzheimer’s disease and in patients with mild cognitive impairment by using diffusion tensor imaging

Purpose

The objective of this study was to evaluate white matter tissue damage in patients with Alzheimer’s disease (AD) and in patients with mild cognitive impairment (MCI) using diffusion tensor imaging (DTI).

Materials and methods

Forty-seven subjects were evaluated: 14 patients with AD, 15 with MCI and 18 healthy volunteers. All subjects were studied using conventional magnetic resonance imaging (MRI) and DTI (32 directions) with a 1.5 T magnet. Fractional anisotropy (FA) was measured in the following regions: frontal, occipital, parietal and temporal white matter and in the genu and splenium of the corpus callosum. The results were compared between the different groups and correlated with the Mini-Mental State Evaluation (MMSE) scores.

Results

A statistically significant difference was obtained between controls and MCI patients (p<0.007) and between controls and AD patients (p<0.05) with regard to FA of the white matter in the splenium. A statistically significant difference was obtained between controls and AD patients with regard to FA in the genu (p<0.016). Moreover, there was a statistically significant difference between controls and AD patients considering the genu (p<0.016) and the frontal white matter on the right side (p<0.024). The MMSE scores correlated with the FA values measured in the genu, the splenium and frontal white matter on the right side. No significant differences were identified between patients with AD and those with MCI.

Conclusions

DTI could be of value in the early detection of white-matter damage in patients with MCI and AD. The DTI values correlate with the neuropsychological tests.     

Diffusion tensor imaging of normal-appearing white matter in mild cognitive impairment and early Alzheimer disease: preliminary evidence of axonal degeneration in the temporal lobe

BACKGROUND AND PURPOSE: Diffusion tensor imaging (DTI) is a sensitive technique for studying cerebral white matter. We used DTI to characterize microstructural white matter changes and their associations with cognitive dysfunction in Alzheimer disease (AD) and mild cognitive impairment (MCI). MATERIALS AND METHODS: We studied elderly subjects with mild AD (n = 6), MCI (n = 11), or normal cognition (n = 8). A standardized clinical and neuropsychological evaluation was conducted on each subject. DTI images were acquired, and fractional anisotropy (FA), axial diffusivity (DA), and radial diffusivity (DR) of normal-appearing white matter (NAWM) in frontal, temporal, parietal, and occipital lobes were determined. These diffusion measurements were compared across the 3 groups, and significant differences were further examined for correlations with tests of cognitive function. RESULTS: Compared with normal controls, AD subjects demonstrated decreased FA and increased DR in the temporal, parietal, and frontal NAWM and decreased DA in temporal NAWM. MCI subjects also showed decreased FA and decreased DA in temporal NAWM, with decreased FA and increased DR in parietal NAWM. Diffusion measurements showed no differences in occipital NAWM. Across all subjects, temporal lobe FA and DR correlated with episodic memory, frontal FA and DR correlated with executive function, and parietal DR significantly correlated with visuospatial ability. CONCLUSIONS: We found evidence for functionally relevant microstructural changes in the NAWM of patients with AD and MCI. These changes were present in brain regions serving higher cortical functions, but not in regions serving primary functions, and are consistent with a hypothesized loss of axonal processes in the temporal lobe.     

婴幼儿发育迟缓的脑磁共振扩散张量成像研究

目的应用磁共振扩散张量成像(DTI)研究发育迟缓婴幼儿脑白质的各向异性(FA)值,探讨其与正常婴幼儿脑白质有无差异。资料与方法对40例发育迟缓和40例正常婴幼儿进行了常规MRI及DTI扫描,并以常规MRI表现将发育迟缓组分为常规MRI表现正常和常规MRI表现脑白质发育迟缓。分别测量5个深部脑白质与4个浅部脑白质的FA值,并对结果进行统计学比较。结果发育迟缓组各测量部位FA值低于对照组,除内囊后肢外差异均有统计学意义(P<0.05)。发育迟缓常规MRI表现正常患儿深部脑白质FA值低于正常组,但差异无统计学意义(P>0.05);浅部脑白质FA值低于正常组,差异有统计学意义(P<0.05);发育迟缓常规MRI表现发育迟缓脑白质FA值均低于正常组,差异有统计学意义(P<0.05)。结论应用DTI FA值的测量能定量诊断婴幼儿脑白质发育迟缓,尤其常规MRI正常的发育迟缓患儿浅部脑白质FA值低于对照组,可明确诊断发育迟缓。     

基于体素的遗忘型轻度认知障碍和轻度阿尔茨海默病全脑白质MR扩散张量成像分析

目的 采用基于体素的分析(VBA)方法研究遗忘型轻度认知障碍(aMCI)患者和轻度阿尔茨海默病(AD)患者全脑白质微观结构改变的特点及其与灰质萎缩模式的关系.方法 选取33例aMCI患者(aMCI组)、32例轻度AD患者(轻度AD组)和31名正常老年人(健康对照组),对全脑进行3.0 T DTI及三维快速扰相梯度反转回波(3DFSPGR)脉冲序列扫描.采用统计参数图(SPM)5软件对被试者的结构图像及各向异性(FA)图进行预处理,然后采用t检验对aMCI组、轻度AD组和正常对照组的全脑灰质体积及FA值进行基于体素的统计学比较,计算出有统计学意义的脑区.结果 与正常对照组比较,aMCI组的双侧额颞叶和左侧枕叶白质、左侧扣带前部、左侧顶下小叶、右侧脑室三角区外上方白质的FA值减低;轻度AD组的双侧额颞枕叶、海马旁白质、扣带前部、胼胝体、侧脑室三角区旁白质、顶下小叶、左侧颞于、左侧丘脑、右侧楔前叶FA值减低.基于体素的形态测量学(VBM),分析发现,aMCI患者组左侧海马、海马旁回、舌回、颞上回,双侧岛叶、颞中回出现了灰质萎缩;轻度AD患者组双侧海马、海马旁回、杏仁核、丘脑、额叶、颞叶、顶叶、枕叶皮质出现了灰质萎缩.aMCI与轻度AD患者组全脑白质FA值减低的模式与灰质萎缩模式不同.aMCI组与轻度AD组比较未发现具有统计学意义的FA值减低脑区.aMCI、轻度AD患者组全脑白质FA值与简易智能精神状态检查量表(MMSE)评分没有相关性.结论 基于体素的MR DTI全脑白质分析能够较全面、客观地揭示aMCI、轻度AD的脑白质损害的模式.aMCI、轻度AD患者白质损害的模式与灰质不同,提示脑白质病变是多种病理机制导致的.aMCI患者向轻度AD进展过程中,脑白质各向异性改变不显著,脑白质FA值的改变可能无法反映患者认知功能障碍的严重程度.

Abstract：

Objective To evaluate the microstructural integrity of white matter (WM) in patients with amnestic mild cognitive impairment (aMCI) and mild Alzheimer's disease (AD) using voxel-based analysis (VBA), and investigate the relationship between WM abnormalities and gray matter(GM) atrophy.Methods Thirty-three cases with aMCI, 32 cases with mild AD and 31 normal aging volunteers as control subjects were scanned on a 3.0 T MR system using diffusion tensor imaging (DTI) and three-dimensional spoiled gradient-recalled(3DSPGR) sequences. Fractional anisotropy (FA) maps and morphological images were preprocessed by SPM5 and voxel-based comparisons between the 2 patient groups and the control group were performed by t test. Results Relative to the control group, patients with aMCI showed significantly reduced FA value in bilateral frontal, temporal and left occipital WM, left anterior part of cingulum, left inferior parietal lobule, and the W M adjacent to the triangular part of the right lateral ventricle(k≥20 voxels).In mild AD,significantly reduced FA value was found in bilateral hippocampal,inferior parietal lobular,frontal,temporal,and occipital WM,bilateral corpus callosum,anterior part of cingulums,the WM adjacent to the triaangular part of the bilateral lateral ventricles,left temporal stem,left thalamus,right precuneus(k≥20 voxels).Significantly reduced GM volume was found in left hippocampus,parahippocampal gyrus,lingual gyrus and superior temporal gyrus,bilateral insulae and middle temporal gyri in aMCl group whencompared with control group(k≥50 voxels).In mild AD,significantly reduced GM volume was found in bilateral hippoeampi,parahippocampal gyri,amygdalae,thalami,temporal,parietal,frontal,occipital cortex(k≥50 voxels).The pattern of areas with reduced FA differs;from that of the GM volumetric reduction.No areas with significantlv reduced FA was detected in aMCl compared with mild AD. There was no significant correlation between FA value of WM in patient groups and Mini-Mental State Examination(MMSE)scores.Conclusions Voxel-based MRI DTI analysis of whole brain white matter can objectively reveal widespread white matter abnormalities in early-stage AD.The difierence between WM FA reduction pattern and GM volumetric reduction pattern indicates that the pathological WM changes in earlyslage AD were caused by multiple mechanisms. FA did not vary significantly in patients pr0gressing from aMCI to mild AD and can hardly reflect the severitv of cognitive function damage in these patients.     

Whole brain white matter changes revealed by multiple diffusion metrics in multiple sclerosis: a TBSS study

Objective

To investigate whole brain white matter changes in multiple sclerosis (MS) by multiple diffusion indices, we examined patients with diffusion tensor imaging and utilized tract-based spatial statistics (TBSS) method to analyze the data.

Methods

Forty-one relapsing-remitting multiple sclerosis (RRMS) patients and 41 age- and gender-matched normal controls were included in this study. Diffusion weighted images were acquired by employing a single-shot echo planar imaging sequence on a 1.5 T MR scanner. Voxel-wise analyses of multiple diffusion metrics, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) were performed with TBSS.

Results

The MS patients had significantly decreased FA (9.11%), increased MD (8.26%), AD (3.48%) and RD (13.17%) in their white matter skeletons compared with the controls. Through TBSS analyses, we found abnormal diffusion changes in widespread white matter regions in MS patients. Specifically, decreased FA, increased MD and increased RD were involved in whole-brain white matter, while several regions exhibited increased AD. Furthermore, white matter regions with significant correlations between the diffusion metrics and the clinical variables (the EDSS scores, disease durations and white matter lesion loads) in MS patients were identified.

Conclusion

Widespread white matter abnormalities were observed in MS patients revealed by multiple diffusion metrics. The diffusion changes and correlations with clinical variables were mainly attributed to increased RD, implying the predominant role of RD in reflecting the subtle pathological changes in MS.     

正常成人大脑白质纤维各向异性特征的弥散张量磁共振成像研究

目的：利用弥散张量磁共振成像研究正常成人大脑白质纤维的各向异性特征。材料和方法：应用弥散张量磁共振成像方法，观察10例正常志愿者的大脑白质纤维的FA图像，分别测量两侧大脑半球相对称的5个感兴趣区即外囊、内囊前肢、内囊后肢、胼胝体前部、胼胝体后部的FA值，并进行比较。结果：在FA图像上可清楚地观察到大脑白质纤维结构，呈高信号，各个部位信号是不同的，胼胝体信号较其他部位高，尤以压部信号最高。5个感兴趣区的FA值是外囊0．41、内囊前肢0．48、内囊后肢0．71、胼胝体前部0．72、胼胝体后部0．86。各个兴趣区之间进行秩和检验，结果为胼胝体后部与外囊比较有统计显著差异，胼胝体后部与内囊前肢比较有统计显著差异，胼胝体前部与外囊相比较亦有统计显著差异，其余各兴趣区之间相比较无统计显著差异。结论：弥散张量磁共振成像方法有效地显示大脑白质纤维的各向异性特，缸，为正确认识大脑白质纤维的正常解剖提供更多有价值的信息。     

3.0T磁共振扩散张量成像FA值在新生儿HIE早期诊断中的研究

目的探讨磁共振扩散张量成像(DTI)技术特征参数各向异性分数(FA)值定量测量在评价新生儿缺氧缺血性脑病(HIE)中的临床应用价值。方法搜集临床确诊为HIE的患儿25例(轻度组8例,中度组6例,重度组11例)及正常对照组新生儿7例,应用3.0T磁共振对所有患儿及正常新生儿行颅脑MRI常规序列和DTI序列扫描。测量HIE各组及对照组新生儿颅脑各感兴趣区的FA值并分析各组间的FA值差异是否具有统计学意义。结果重度组患儿额叶深部髓质、顶枕叶深部髓质、小脑半球、内囊后支、豆状核区、丘脑FA值较对照组新生儿明显降低(P值均<0.05),中度组/轻度组患儿额叶深部髓质、小脑半球、内囊后支、豆状核区、丘脑FA值较对照组新生儿明显降低(P值均<0.05),病例组患儿脑干FA值较对照组新生儿降低,但差异无统计学意义;重度组患儿额叶深部髓质FA值较轻度组患儿明显降低(P值=0.000),顶枕叶深部髓质FA值较轻度组患儿明显降低(P值=0.002),豆状核区FA值较轻度组患儿(P值=0.000)、中度组患儿(P值=0.004)明显降低,其余组间比较差别没有统计学意义。结论 FA值定量测量可作为新生儿HIE早期诊断客观依据,为HIE患儿制定治疗方案和评估预后提供帮助。     

急性一氧化碳中毒脑损伤的磁共振扩散张量成像

目的：利用磁共振扩散张量成像(DTI )评估急性一氧化碳(CO)中毒患者的脑结构损伤情况。方法25例急性(5.0 d±1.44 d) CO 中毒患者和37例性别、年龄、利手、受教育程度匹配的健康志愿者进行 DTI 扫描,获得扩散张量纤维束成像(DTT)图像,并分别测量双侧小脑半球(齿状核)、黑质、海马、额叶白质(侧脑室前角前下方、侧脑室体部上方)、尾状核头、苍白球、丘脑、内囊前肢、内囊后肢、枕叶白质(视中枢)、顶叶白质(侧脑室体部上方)及胼胝体膝部、压部共26个感兴趣(ROI)的各向异性分数(FA)值和表观扩散系数(ADC)值,进行组间配对 t 检验。结果病患组双侧苍白球、双侧内囊前肢、双侧黑质、右侧小脑、左侧额叶下部白质、右额叶上下部白质、胼胝体膝部的 FA 值显著低于对照组(P <0.05)。病患组右侧黑质、左侧苍白球的 ADC 值显著降低(P <0.05),病患组右额叶上下部白质及双侧枕叶白质 ADC 值显著升高(P <0.05)。结论急性 CO 中毒患者广泛脑微结构受损,提示脑微结构的原发损伤可能是 CO 中毒迟发性脑病潜在的病理生理基础。     

Diffusion abnormalities of the uncinate fasciculus in Alzheimer’s disease: diffusion tensor tract-specific analysis using a new method to measure the core of the tract

Introduction Our aim was to determine diffusion abnormalities in the uncinate fasciculus (UF) in Alzheimer’s disease (AD) by diffusion tensor tractography (DTT) using a new method for measuring the core of the tract. Methods We studied 19 patients with AD and 19 age-matched control subjects who underwent MRI using diffusion tensor imaging (DTI). DTT of the UF was generated. The mean diffusivity (MD) and fractional anisotropy (FA) of the core of the tract were measured after voxelized tract shape processing. Student’s t-test was used to compare results between patients with AD and controls. Intraobserver correlation tests were also performed. Results FA was significantly lower (P < 0.0001) in the UF of patients with AD than of controls. There was no significant difference in MD along the UF between the two groups. Intraobserver reliability (intraclass correlation coefficient) for the first and second measurement was r > 0.93 for measured FA and r > 0.92 for measured MD. Conclusion Our results suggest that FA reflects progression of AD-related histopathological changes in the UF of the white matter and may represent a useful biological index in monitoring AD. Diffusion tensor tract-specific analysis with voxelized tract shape processing to measure the core of the tract may be a sensitive tool for evaluation of diffusion abnormalities of white matter tracts in AD.     

MR扩散张量成像对脑肿瘤的初步应用研究

目的 :评价MR扩散张量成像在脑肿瘤中的应用价值。方法 :搜集经手术及病理证实的脑膜瘤和星形细胞瘤病例共 3 3例 ,行常规MRI、扩散张量成像 (DTI)检查。构建各向异性分数 (FA)图 ,并测量肿瘤及周围白质的FA值。结果 :正常白质纤维在FA图上表现为高信号。在肿瘤存在时 ,周围白质纤维可表现为受推压移位或浸润破坏 ,破坏后FA值降低 ,表现为低信号。这些表现在常规MRI上均未清楚显示。结论 :DTI可清楚显示肿瘤与周围白质纤维的解剖关系 ,指导临床制订手术方案。     

Diffusion tensor images in children with early-treated, chronic, malignant phenylketonuric: correlation with intelligence assessment

BACKGROUND AND PURPOSE: Diffusion tensor (DT) images can provide information about the nature of white matter changes, including axonal loss and demyelination. We applied DT imaging to verify white matter changes in patients with malignant phenylketonuria (PKU) and to correlate the findings with clinical intelligence quotients (IQs). METHODS: We compared DT images with T2-weighted images in 12 patients with early-treated, chronic, stable malignant PKU and 12 age-matched control subjects. DT parameters included first, second, and third eigenvalues (EV1-3), apparent diffusion coefficients (ADCs), and fractional anisotropy (FA). Regions of interest were placed the frontoparietal, parieto-occipital, frontal and central white matter and in the anterior and posterior corpus callosum. Eight patients older than 3 years underwent IQ assessment including verbal, performance, and full-scale IQ tests. RESULTS: In the eight patients older than 3 years, no definite abnormal signal intensity changes were found on T2-weighted images. EV2, EV3, and FA of the parieto-occipital white matter were significantly different in patients and control subjects older than 3 years. EV3 and ADC of the parieto-occipital white matter were significantly and negatively correlated with verbal IQ (r = -0.79, P = .04) and performance IQ (r = -0.93, P = .03). FA of the parieto-occipital central white matter was positively correlated with verbal IQ (r = 0.75, P = .05). CONCLUSION: Though treated early, patients with chronic, stable malignant PKU had abnormal DT findings in the parieto-occipital central white matter. EV2, EV3, and FA maps are potential tools for demonstrating brain changes due to malignant PKU.     

The cervical spinal cord in neuromyelitis optica patients: a comparative study with multiple sclerosis using diffusion tensor imaging

Introduction

This study aims to evaluate “in vivo” the integrity of the normal-appearing spinal cord in patients with neuromyelitis optica (NMO), using diffusion tensor MR imaging, comparing to controls and patients with multiple sclerosis (MS).

Materials and methods

We studied 8 patients with NMO and 17 without any neurologic disorder. Also, 32 MS patients were selected. Fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD) and mean diffusivity (MD) were calculated within regions of interest at C2 and C7 levels in the four columns of the spinal cord.

Results

At C2, the FA value was decreased in NMO patients compared to MS and controls in the anterior column. Also in this column, RD value showed increase in NMO compared to MS and to controls. The FA value of the posterior column was decreased in NMO in comparison to controls. At C7, AD value was higher in NMO than in MS in the right column. At the same column, MD values were increased in NMO compared to MS and to controls.

Conclusions

There is extensive NASC damage in NMO patients, including peripheral areas of the cervical spinal cord, affecting the white matter, mainly caused by demyelination. This suggests a new spinal cord lesion pattern in NMO in comparison to MS.     

2个CADASIL患者的弥散张量成像与20例正常人的比较

目的　分析2例CADASIL患者的MR特点及弥散张量指标的变化。方法　收集2例通过病理和基因检查确诊为CA DASIL的先证者的临床资料,对其进行常规MR扫描和弥散张量成像,将弥散张量成像的指标与20例正常志愿者的指标进行比较。结果　2例CADASIL患者的MR主要表现为双侧额顶叶白质内多发腔梗、脱髓鞘改变和双侧颞叶前部白质脱髓鞘。1例患者双侧外囊、内囊后肢、胼胝体膝部和压部的部分各向异性(FA)值均小于正常组的平均值减去2倍标准差,另1例患者左侧外囊的FA值小于对照组的平均值减去2倍标准差。结论　常规MR表现和弥散张量成像指标的测量均反映了CADASIL患者中存在严重的白质病变。     

抑郁症患者脑白质纤维的各向异性变化

目的：探讨MRI DWI上抑郁症患者脑白质纤维的各向异性特征。方法：对9例抑郁症患者以及与患者组年龄、性别相匹配的10例志愿者（对照组）行MR扩散张量成像（DTI）。记录额叶、颞叶、枕叶和胼胝体白质的各向异性分值（FA值）。结果：抑郁症患者左右额叶上中下部、左右颞叶、胼胝体压部的脑白质FA值均低于对照组,差异有显著性意义（P〈0.05）。结论：抑郁症患者的额叶和颞叶的白质纤维束FA值比正常人低,而且左右侧不对称。     

早期帕金森病患者脑白质损害的扩散张量成像研究

目的:采用基于纤维束示踪的空间统计方法分析(TBSS)早期帕金森病患者扩散张量成像(DTI)数据,研究早期帕金森病患者脑白质结构损害情况及与运动症状的相关性.方法:18例早期帕金森病(PD)患者(Hoehn-Yahr 1～2级)及22例健康志愿者(对照组)行DTI扫描,采用TBSS技术对两组受试者的DTI数据进行分析,比较两组受试者脑白质纤维的部分各向异性(FA)值的差异,及其与帕金森病评估量表(UPDRS-Ⅲ)评分的相关性,测量并比较先发病侧与对侧大脑白质的FA值.结果:全脑分析显示:与正常对照组相比,PD组双侧额顶部、放射冠、胼胝体和扣带回的脑白质FA值明显减低(P＜0.05),且其范围均与UPDRS-Ⅲ评分呈负相关(r=-0.479～-0.736,P＜0.05);早期PD患者先发病侧大脑与对侧大脑比较,后放射冠、顶叶及颞叶的脑白质FA值的差异有统计学意义(P＜0.05).结论:早期PD患者即可见脑白质纤维结构的改变,大脑白质损害程度与PD患者运动症状有密切联系,PD患者脑白质损害的部位可能存在一定的顺序.     

A preliminary diffusional kurtosis imaging study of Parkinson disease: comparison with conventional diffusion tensor imaging

Introduction

Diffusional kurtosis imaging (DKI) is a more sensitive technique than conventional diffusion tensor imaging (DTI) for assessing tissue microstructure. In particular, it quantifies the microstructural integrity of white matter, even in the presence of crossing fibers. The aim of this preliminary study was to compare how DKI and DTI show white matter alterations in Parkinson disease (PD).

Methods

DKI scans were obtained with a 3-T magnetic resonance imager from 12 patients with PD and 10 healthy controls matched by age and sex. Tract-based spatial statistics were used to compare the mean kurtosis (MK), mean diffusivity (MD), and fractional anisotropy (FA) maps of the PD patient group and the control group. In addition, a region-of-interest analysis was performed for the area of the posterior corona radiata and superior longitudinal fasciculus (SLF) fiber crossing.

Results

FA values in the frontal white matter were significantly lower in PD patients than in healthy controls. Reductions in MK occurred more extensively throughout the brain: in addition to frontal white matter, MK was lower in the parietal, occipital, and right temporal white matter. The MK value of the area of the posterior corona radiata and SLF fiber crossing was also lower in the PD group.

Conclusion

DKI detects changes in the cerebral white matter of PD patients more sensitively than conventional DTI. In addition, DKI is useful for evaluating crossing fibers. By providing a sensitive index of brain pathology in PD, DKI may enable improved monitoring of disease progression.