轻型创伤性脑损伤脑白质纤维束扩散张量成像研究

目的：使用3.0T 磁共振扩散张量成像(DTI)技术观察轻型创伤性脑损伤(mTBI)患者脑白质纤维束的改变,探讨 DTI对 mTBI 的临床诊断价值。方法选取30例 mTBI 患者及30例健康对照者分别进行常规 CT、MRI 及 DTI 检查,分别测量 mTBI患者(急性期、亚急性期、伤后5周~3个月)和对照者的胼胝体膝部、压部、双侧内囊前后肢、扣带束、上纵束、下纵束的各向异性(FA)值、表观扩散系数(ADC)值,观察各测量值的变化规律。结果mTBI 患者部分脑白质纤维束区的 FA 值在急性期、亚急性期减低(P 均<0.05),伤后5周~3个月时仍低于对照者(P 均<0.05),但胼胝体膝部及压部的 FA 值在急性期不减低反而升高(P 均>0.05),此后呈逐渐减低趋势,并在外伤5周~3个月时略低于正常对照组,但差异无统计学意义(P 均>0.05)。急性期、亚急性期 mTBI 患者的 ADC 值低于正常对照组,并在外伤5周~3个月时接近或略高于对照组,但差异无统计学意义(P 均>0.05)。结论DTI 对 mTBI 敏感性较高,能够准确显示白质纤维束的损伤情况并使其可视化,DTI 对 mTBI 的诊断具有重要的临床价值。     

DTI对HIV感染者脑白质细微结构病变的诊断研究

目的 探讨扩散张量成像(DTI)技术对人类免疫缺陷病毒(HIV)感染者脑白质细微病变的诊断和临床应用价值.方法选取80例HIV阳性者(阳性组)和83例HIV阴性者(对照组),均行MRI常规序列及DTI扫描.测定双侧内囊前支、内囊后支、内囊膝、胼胝体膝部、压部及双侧胼胝体干脑白质感兴趣区(ROI)的各向异性分数(FA)值和表观扩散系数(ADC)值,利用独立样本t检验比较2组间FA值及ADC值的差异.结果与正常对照组相比,阳性组双侧内囊前支及内囊膝、胼胝体膝部及双侧胼胝体干FA值均低于对照组,差异有统计学意义(P<0.05);阳性组双侧内囊前支、后支、膝部及双侧胼胝体干ADC值均高于对照组,差异亦有统计学意义(P<0.05).结论DTI通过FA值和ADC值的异常改变而发现HIV阳性患者内囊及胼胝体区脑白质结构的细微病变,为临床早期诊断和治疗干预提供参考依据.     

青年抑郁症患者胼胝体MR扩散张量成像研究

目的 研究青年抑郁症患者胼胝体可能存在的细微结构异常。资料与方法 对54例青年抑郁症患者（抑郁症组）和38名年龄和性别匹配的正常志愿者（对照组）进行扩散张量成像（DTI）检查,测量胼胝体膝部、体部和压部的表观扩散系数（ADC）值和各向异性分数（FA）,并对两组进行对比分析。结果 抑郁症组患者胼胝体膝部和体部的ADC值明显高于正常对照组,FA值明显低于对照组,P值均〈0．01;胼胝体压部的ADC值和FA值在两组间差异无统计学意义（P〉0．05）。抑郁症组内ADC、FA值的性别差异无统计学意义（P〉0．05）。结论 青年抑郁症患者胼胝体膝部和体部白质纤维束可能存在细微结构的改变。     

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 alterations in corpus callosum of patients with HIV

BACKGROUND AND PURPOSE: Diffusion alterations have been identified in the corpus callosum and frontal white matter of patients infected with human immunodeficiency virus (HIV), though the relevance of these findings to cognitive deterioration has not yet been determined. This study tested the hypothesis that diffusion tensor imaging can detect tissue status alterations in these regions in cognitively impaired patients infected with HIV and the acquired measurements correlate with the severity of cognitive impairment. METHODS: Fractional anisotropy (FA) and mean diffusivity (MD) were determined for corpus callosum (genu and splenium) and frontal white matter (FWM). The DTI measurements were compared in 11 HIV and 11 control participants. Patterns of relationship were examined with cognitive status measures from concurrent neurologic and neuropsychologic evaluations. RESULTS: FA values for the splenium were significantly reduced in the patients infected with HIV and correlated with dementia severity and deficits in motor speed. MD values for the splenium were significantly increased in the patients infected with HIV and correlated with deficits in motor speed. FA measurements were also significantly correlated with performance on visual memory (genu), visuoconstruction (FWM), and verbal memory (FWM) tasks. CONCLUSION: Diffusion abnormalities were identified in the splenium of the corpus callosum in patients infected with HIV, and these alterations were associated with dementia severity and motor speed losses. In vivo assessment of callosal integrity by using quantitative neuroimaging may have potential utility as a marker of brain injury in patients infected with HIV.     

DTI在PVL合并脑瘫患儿术后脑白质恢复中的应用价值

目的 探讨扩散张量成像(DTI)技术在脑室周围白质软化症(PVL)合并脑瘫患儿术后脑白质恢复中的应用价值.方法 收集经临床诊断为PVL合并脑瘫患儿15例作为病例组,另选相匹配的正常儿童志愿者15例作为对照组,均进行常规MRI平扫及DTI检查,并获得各向异性分数(FA)图,测量病例组治疗前后与对照组皮质脊髓束(内囊膝、内囊后肢、大脑脚及脑桥水平)、基底节区核团(尾状核、豆状核)感兴趣区的FA值差异.结果 双侧内囊膝、内囊后肢、脑桥、胼胝体压部、膝部及双侧大脑脚的FA值在病例组治疗前、后(术后1个月)与对照组间有统计学差异(P＜0.05),3组豆状核、尾状核的FA值无统计学意义.进一步两两比较,双侧内囊后肢、胼胝体压部、膝部任意2组间比较均有统计学差异,双侧内囊膝、脑桥、双侧大脑脚治疗前、后无统计学意义,双侧内囊膝、脑桥、双侧大脑脚治疗前与对照组间比较均有统计学意义(P＜0.05).结论 DTI技术可显示脑白质细微结构变化,其FA值在PVL合并脑瘫患儿术后脑白质恢复中有一定参考价值,有助于指导临床医生进一步合理治疗.     

磁共振扩散张量成像对正常人脑结构的显示及各向异性研究

目的 探讨不同脑组织结构在扩散张量成像（DTI）中的信号特点及各向异性。资料与方法 对20名正常人行DTI,分析其平均扩散系数（ADC）图及部分各向异性（FA）图的特点,并对不同感兴趣区（ROI）进行ADC及FA值的测量,通过统计学分析得出其扩散和各向异性特点。结果男女之间比较,同一部位的ADC及FA值差异均无统计学意义（P〉0．05）,对称结构而言,左右侧的ADC或FA值相比差异也无统计学意义（P〉0．05）。ADC图上脑脊液呈明显的高信号,而其余脑组织呈不同程度的较低信号,且信号差别不大。侧脑室体部内的脑脊液与其他ROIADC值相比,差异有统计学意义（P〈0．05）,而其余ROI之间的ADC值则无差异（P〉0．05）。FA图可以清晰反映脑白质纤维,呈明显的高信号。不同白质纤维的FA值不一致,胼胝体压部的FA值最大,并与胼胝体膝部差异无统计学意义（P〉0．05）。与其他测量结构差异有统计学意义（P〈0．05）。脑白质的各向异性按胼胝体、内囊、半卵圆中心、外囊逐渐降低。侧脑室体部内脑脊液的FA值最低。结论 不同部位脑组织的各向异性及信号不同。ADC图主要体现脑脊液与其他脑组织的差异,而FA图可以清晰显示脑内的白质纤维,并能定量反映不同部位各向异性的特征。     

DTI评价不同期HIV相关性痴呆脑白质微细结构损害

目的:应用磁共振扩散张量成像(DTI)技术研究不同期HIV相关性痴呆(HAD)患者脑白质微细结构的改变.方法:对17例HAD患者(中重度组9例,亚临床组8例)及10例年龄性别相匹配的健康对照组行常规MRI及DTI检查,测量其额叶、顶叶、颞叶、枕叶、胼胝体膝部、压部、内囊前、后肢白质区部分各向异性分数(FA)和表观扩散系...     

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.     

Early postnatal development of corpus callosum and corticospinal white matter assessed with quantitative tractography

BACKGROUND AND PURPOSE: The early postnatal period is perhaps the most dynamic phase of white matter development. We hypothesized that the early postnatal development of the corpus callosum and corticospinal tracts could be studied in unsedated healthy neonates by using novel approaches to diffusion tensor imaging (DTI) and quantitative tractography. MATERIALS AND METHODS: Isotropic 2 x 2 x 2 mm(3) DTI and structural images were acquired from 47 healthy neonates. DTI and structural images were coregistered and fractional anisotropy (FA), mean diffusivity (MD), and normalized T1-weighted (T1W) and T2-weighted (T2W) signal intensities were determined in central midline and peripheral cortical regions of the white matter tracts of the genu and splenium of the corpus callosum and the central midbrain and peripheral cortical regions of the corticospinal tracts by using quantitative tractography. RESULTS: We observed that central regions exhibited lower MD, higher FA values, higher T1W intensity, and lower T2W intensity than peripheral cortical regions. As expected, MD decreased, FA increased, and T2W signal intensity decreased with increasing age in the genu and corticospinal tract, whereas there was no significant change in T1W signal intensity. The central midline region of the splenium fiber tract has a unique pattern, with no change in MD, FA, or T2W signal intensity with age, suggesting different growth trajectory compared with the other tracts. FA seems to be more dependent on tract organization, whereas MD seems to be more sensitive to myelination. CONCLUSIONS: Our novel approach may detect small regional differences and age-related changes in the corpus callosum and corticospinal white matter tracts in unsedated healthy neonates and may be used for future studies of pediatric brain disorders that affect developing white matter.     

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。     

3.0T MR弥散梯度编码方向对脑组织FA值测量的影响

目的:探讨超高场强MR下弥散张量成像中弥散梯度编码方向对脑组织弥散各向异性分数(FA)的影响。方法:使用3种不同的弥散梯度编码方向(6、13和21个)在3.0T MRI上对14名健康志愿者进行头颅弥散张量成像(DTI)。在FA图上分别测量两侧半卵圆中心、胼胝体膝部、胼胝体压部、两侧内囊、丘脑及桥脑FA值,并进行统计学分析。结果:胼胝体压部FA值最高,其次为胼胝体膝部、内囊和桥脑,丘脑FA值最低。随着弥散梯度编码方向的增加,FA图质量提高,对白质纤维束细节的显示也更清楚,尤其是对脑干结构的分辨,但成像时间延长;3种不同弥散梯度编码方向的DTI扫描方案所观察到的半卵圆中心、胼胝体膝部、胼胝体压部、内囊、丘脑及桥脑的FA值不存在统计学显著性差异。结论:超高场MRI弥散梯度编码方向数目对脑组织FA值的测量无显著性影响,在临床运用中可根据患者状况选择弥散梯度编码方向,以提高DTI检查的成功率。     

多发性硬化的正常表现脑白质的DTI定量

目的：应用磁共振弥散张量成像（DTI）技术，定量研究多发性硬化（MS）患者在常规磁共振上表现正常的脑白质（NAWM），以及探讨其相关的微观病理改变。材料和方法：采用3．0T磁共振仪，对34例Ms患者和25例性别年龄相匹配的正常志愿者均进行DTI检查。分别测量MS组和对照组的9个不同部位脑白质的平均弥散率（MD）和部分各向异性指数（FA值），这9个部位包括胼胝体膝部、体部、压部、内囊后肢、侧脑室旁白质、额叶白质、顶叶白质、枕叶白质以及小脑中脚。比较两组NAWM之间的MD和FA值是否存在差异。结果：MS组的NAWM的MD值均高于对照组（P〈0．05），以胼胝体体部、内囊、侧脑室旁及额叶白质、顶叶白质、枕叶白质更为显著（P〈0．01）；MS组的FA值与对照组比较，胼胝体体部、顶叶白质、额叶白质、枕叶白质及内囊、侧脑室旁发现明显降低（P〈0．05），以后4个部位更为显著（P〈0．01），而胼胝体膝部、压部和小脑结合臂有降低趋势，但无统计学意义。结论：应用DTI定量研究可以探测到多发性硬化的NAWM所出现的微观病理改变，表现为水分子的平均弥散幅度明显升高，以幕上明显，并且胼胝体体部、内囊后肢等白质纤维明显失去正常的方向性。DTI在对白质损伤程度的量化评估中具有重要的价值。     

正常成人胼胝体磁共振轴位及矢状位DTI定量研究

目的:研究正常成人胼胝体磁共振轴位扩散张量成像(DTI)与矢状位DTI各向异性(FA)可能的差异,探讨2种测量方法的可靠性。方法:对68例健康志愿者分别行轴位和矢状位DTI扫描,年龄18～78岁。分别测量胼胝体膝部及压部的FA值。对相同部位的轴位和矢状位测量结果进行比较,并行相关性分析。结果:矢状位上测量的胼胝体膝部FA值大于轴位,且两者之间差异有统计学意义(t=-5.833,P<0.001)。胼胝体压部FA值在矢状位与轴位上差异无统计学意义(t=0.435,P>0.05)。结论:矢状位与轴位DTI测量的胼胝体膝部及压部FA值不同,矢状位DTI能研究胼胝体各个区域各向异性的变化。     

DTI和T1WI测值法在早产儿脑发育评估中的应用价值

目的:探讨磁共振扩散张量成像(DTI)和T1WI测值法在早产儿脑发育评估中的应用价值.方法:将32例早产儿根据分娩孕周分为早期早产儿组(出生胎龄≤32周,19例)和中晚期早产儿组(出生胎龄>32周,13例),均进行DTI检查,测量感兴趣区(ROI)的各向异性分数(FA)值和表观扩散系数(ADC)值.ROI包括胼胝体压部...     

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...     

Evaluation of the anisotropy in the patients with Alzheimer's disease

Diffusion-weighted MR imaging was performed in 5 control subjects and 8 patients with Alzheimer's disease(AD). The mean values of fractional anisotropy(FA) were calculated in the genu and splenium of the corpus callosum, and anterior and posterior cerebral white matter. The FA value of the posterior white matter in patients with AD was significantly lower than that of controls. Fractional anisotropy may be useful in the diagnosis of AD.     

Cerebral white matter damage in frontotemporal dementia assessed by diffusion tensor tractography

INTRODUCTION: We used diffusion tensor imaging (DTI) to study white matter integrity in patients with frontotemporal dementia (FTD). METHODS: The subjects comprised 20 patients (9 men, 11 women) with FTD and 17 age-matched healthy controls (9 men, 8 women). Based on the data obtained from DTI, we performed tractography of the major cerebral pathways, including the pyramidal tracts, genu and splenium of the corpus callosum (CC), bilateral arcuate fasciculi (AF), inferior longitudinal fasciculi (ILF) and uncinate fasciculi (UF). We measured the values of fractional anisotropy (FA) in each fiber and statistically compared the findings in patients with those in controls. RESULTS: We found a significant decrease in FA values in the selected association fibers as well as anterior fibers of the CC in the patients with FTD. The greatest decrease in mean FA of the UF was seen in advanced FTD. On the other hand, there were no significant differences in FA in the bilateral pyramidal tracts. CONCLUSION: The features of FTD from the view point of cerebral white matter damage were revealed by tractography based on DTI. DTI is therefore considered to be a useful method, and may provide clues to elucidating the pathogenesis of FTD.     

扩散张量成像在遗忘型轻度认知障碍和Alzheimer病中的应用

目的：探讨磁共振扩散张量成像（DTI）在遗忘型轻度认知障碍（AMCI）、Alzheimer病（AD）诊断中的作用。方法：对20名aMCI患者、20名AD患者、20名正常对照者（NC）行DTI检查,分别在颞叶白质、顶叶白质、海马、胼胝体膝部及压部、上纵束Ⅱ、扣带束测ROI的FA值和ADC值。结果：NC组与aMCI组、aMCI组与AD组比较扣带束FA值均有显著性差异（P〈0．05）;NC组与AD组比较颞叶、海马、胼胝体膝部、扣带束FA值,颞叶、海马ADC值有显著性差异（P〈0．05）。结论：aMCI患者扣带束FA值异常降低;AD患者颞叶、海马、胼胝体膝部、扣带束FA值降低和颞叶、海马ADC值增高,提示DTI检查有助于aMCI、AD患者的早期诊断。     

Diffusion tensor imaging in patients with acute onset of neuropsychiatric systemic lupus erythematosus: a prospective study of apparent diffusion coefficient, fractional anisotropy values, and eigenvalues in different regions of the brain

PURPOSE: To investigate whether apparent diffusion coefficient (ADC), fractional anisotropy (FA), and eigenvalues in neuropsychiatric systemic lupus erythematosus (NPSLE) patients differ from those of healthy controls. MATERIAL AND METHODS: Eight NPSLE patients (aged 23-55 years, mean 42.9 years) and 20 healthy age-matched controls (aged 22-59 years, mean 44.4 years) underwent conventional brain magnetic resonance (MR) and diffusion tensor imaging (DTI). The ADC, FA, principal eigenvalue (lambda parallel), and the corresponding average perpendicular eigenvalue (lambda perpendicular) (=(lambda2+lambda3)/2) were measured in selected regions of normal appearing gray and white matter brain parenchyma. For statistical evaluation of differences between the two groups, a Student's t-test was used. The P value for statistical significance was set to P=0.0025 after Bonferroni correction for multiple measurements. RESULTS: Significantly increased ADC values were demonstrated in normal-appearing areas in the insular cortex (P<0.001), thalamus (P<0.001), and the parietal and frontal white matter (P<0.001 and P<0.001, respectively) in NPSLE patients. Significantly decreased FA values were demonstrated in normal-appearing thalamus (P<0.001), corpus callosum (P=0.002), and in the parietal and frontal white matter (P<0.001 and P<0.001, respectively) in NPSLE patients compared to healthy controls. The lambda perpendicular was significantly higher in several of these regions in NPSLE patients compared to healthy controls. CONCLUSION: Our study demonstrates alterations in normal-appearing gray and white matter brain parenchyma of patients with NPSLE by means of abnormal ADC, FA, and eigenvalues. These alterations may be based on loss of tissue integrity in part due to demyelination. It is possible that DTI in the future could assist in the diagnosis of NPSLE and possibly help to further elucidate the pathogenesis of NPSLE.