核磁共振弥散张量成像在脑胶质瘤诊断中的应用研究

目的 探讨MRI弥散张量成像（DTI）技术显示胶质瘤与相邻脑白质纤维束解剖关系在脑胶质瘤诊断中的意义.方法 23例脑胶质瘤患者接受术前常规头颅MRI序列检查的同时进行DTI序列扫描,应用Functool软件进行图像分析处理,分别获得各自的部分各向异性图（FA图）、彩色编码张量图及脑白质纤维束图;并测定胶质瘤肿瘤病灶区、灶周水肿区及正常白质区的平均弥散系数（MD值）、各向异性图;进行FA图像信号强度及对比度的分析研究,分析脑胶质瘤与相邻脑白质纤维束的解剖关系.结果 所有病例均成功实现包括DTI序列扫描以及FA图像生成.脑白质纤维束显示为显著的高信号结构,灰质显示为等信号,脑脊液显示为低信号,脑内肿瘤呈类圆形等低信号,灶肿瘤周围间质水肿区白质纤维束仍能在DTI的FA图上显像,DTI的FA图像对于脑白质纤维束显影的信号对比度明显优于常规的T1W图像.肿瘤病灶区和灶周水肿区与正常白质区的MD值比较差异均有统计学意义（均P＜0.05）,而肿瘤病灶区与灶周水肿区的MD值比较差异无统计学意义（P＞0.05）;3个区域的FA值比较差异均有统计学意义（均P＜0.05＝.结论 磁共振DTI技术可在活体清晰、无创、直观地显示脑胶质瘤与周围脑白质纤维束的关系,结合其他序列的MRI应用于脑胶质瘤的术前诊断,可以准确判断肿瘤和周围脑白质纤维束的毗邻关系,对脑胶质瘤术前诊断、手术方案设计以及术后神经功能障碍的预测与预防具有重要意义.     

磁共振弥散张量成像对良 恶性脑膜瘤诊断的初探

目的运用磁共振弥散张量成像(DTI)测量脑膜瘤表现弥散系数(ADC)值、FA值和白质纤维走行图,探讨其对良、恶性脑膜瘤的诊断价值。方法对23例良性脑膜瘤,4例恶性脑膜瘤行弥散张量成像,分别测量肿瘤实质区、瘤周水肿区和瘤周白质区的ADC值和FA值,并根据原始图像重建双侧白质纤维走行图。结果①良、恶性脑膜瘤肿瘤实质区ADC值比较差异有统计学意义;良、恶性脑膜瘤瘤周白质FA值差异有统计学意义。②良性脑膜瘤瘤周白质表现为纤维束受压移位或无明显变化;恶性脑膜瘤瘤周水肿区、瘤周白质均出现较明显的纤维束缺失。结论ADC值和FA值有助于脑膜瘤良、恶性的鉴别;白质纤维走行图能清晰显示肿瘤与白质纤维束的关系。     

磁共振弥散张量成像在脑胶质瘤手术前后的临床应用研究

目的查看MRI弥散张量成像（DTI）在脑胶质瘤的诊断价值。方法对我院34例脑胶质瘤患者进行MRI及DTI检查。测定脑胶质瘤及周围组织的平均弥散系数（MD值）、各向异性指数图（FA值）。观察肿瘤与相邻脑白质纤维束的解剖关系。并患者对手术前后临床症状进行评价。结果 24例确诊为低级别脑胶质瘤（Ⅰ-Ⅱ级）。胶质瘤推移相邻白质纤维束。手术切除充分临床症状缓解明显;10例确诊高级别脑胶质瘤（Ⅲ-Ⅳ级）。胶质瘤浸润破坏相邻白质纤维束。脑白质纤维束缺失及中断。手术切除后临床症状改善不明显;瘤床区MD值显著高于正常白质区,差异有统计学意义（P〈0.05）。瘤周水肿区显著高于正常白质区,差异有统计学意义（P〈0.05）。而瘤床区MD值稍高于瘤周水肿区,差异无统计学意义（P〉0.05）;3个区域FA值比较差异均有统计学意义（P〈0.05）。结论磁共振DTI技术可区分高级别脑胶质瘤瘤床区与周围组织的关系。同时对选择治疗方案有重要价值。对评估手术风险和预后也有重要临床意义。     

磁共振弥散张量成像在功能区胶质瘤手术中的应用研究

目的：探讨研究磁共振弥散张量成像（DTI）在功能区胶质瘤手术中的应用。方法选取符合标准的45例功能区胶质瘤患者,根据WHO的评级将45例患者分为低度恶性组（ n ＝21）与高度恶性组（ n ＝24）。2组患者均采用DTI对感兴趣区进行诊断,比较各感兴趣区表面扩散系数（ ADC）值与各向异性分数（ FA）值的差异,以及低度恶性组与高度恶性组ADC值与FA值的差异。结果肿瘤强化区、脑脊液区以及对侧正常大脑白质ADC值均与水肿区差异有统计学意义（ P ＜0?．05）。脑脊液与对侧正常大脑白质ADC值均与肿瘤强化区差异有统计学意义（ P ＜0．05）。脑脊液与对侧正常大脑白质FA值与水肿区和肿瘤强化区均差异有统计学意义（ P ＜0．05）。低度恶性组的肿瘤强化区与水肿区的ADC值均显著性高于高度恶性组（ P ＜0．05）。低度恶性组与高度恶性组肿瘤强化区与水肿区的FA值差异无统计学意义（ P ＞0．05）。结论通过DTI,能够明确功能区胶质瘤与正常白质之间的关系,为进一步的治疗以及手术提供一定的指导。     

磁共振弥散张量成像评估早期创伤性轴索损伤的价值

目的探讨磁共振弥散张量成像(DTI)对早期创伤性脑损伤(TBI)患者轴索损伤的临床应用价值。方法对21例TBI早期(伤后10d内)患者(TBI组)及10例正常志愿者(对照组)行DTI检查,分别测量两侧大脑半球6个感兴趣区(胼胝体膝部、胼胝体压部、内囊前肢、内囊后肢、外囊及背侧丘脑)的部分各向异性(FA)值,并构建上述部位三维弥散张量纤维束成像(3D-DTT)图。比较以上两组感兴趣区平均FA值的差异,并对TBI组的FA值与临床GCS评分进行相关性分析。结果 FA图像上可以清楚观察到呈高信号的脑白质纤维束,损伤局部呈低信号。TBI组平均FA值为0.562±0.042,明显低于对照组的0.609±0.045(P<0.01)。TBI患者FA值与GCS评分呈正相关(r=0.508,P<0.05)。3D-DTT图可以直观显示胼胝体、内外囊等白质纤维束的损伤情况。结论 FA值的变化反应了TBI患者脑白质纤维束水分子各向异性程度的变化,对评估伤情及判断预后有重要意义。     

精神分裂症患者脑白质纤维不对称性及结构完整性的 MR 弥散张量成像分析

目的：对精神分裂症患者脑白质纤维不对称性及结构完整性的 MR 弥散张量成像分析精神分裂症患者脑白质纤维束损伤及变化情况。方法选取50例患有精神分裂症的患者,将其作为试验组,再选取50例正常的健康人作为对照组,分别采用 MR 弥散张量成像的检测方法对2组患者进行检测,对比分析2组患者的脑白质含量情况以及重建纤维束的数量情况。结果试验组患者的右侧额叶白质、左侧额叶白质、右侧颞叶白质、左侧颞叶白质等部位的蛋白质含量与正常对照组患者比较,差异统计学无意义（P ＞0．05）。试验组患者的胼胝体、右侧钩束、左侧钩束、右侧扣带、左侧扣带、右侧下纵束、左侧下纵束纤维束的数量明显低于对照组（P ＜0．05）。结论MR 弥散张量成像在分析精神分裂症患者脑白质纤维束损伤过程中应用效果显著,值得广泛推广。     

老年痴呆患者脑白质结构的扩散加权成像研究

目的 应用扩散加权成像(diffusion weighted imaging,DWI)阐明阿尔茨海默病（AD）脑白质微结构平均弥散系数(ADC)的变化,进一步探讨脑白质微结构改变与认知功能损害之间的关系。方法 选取AD组及对照组各30例。所有受检者均进行神经科查体和简易智能精神状态量表(MMSE)测试,对常规脑部MRI脑白质表现正常的部位行DWI检查,测量不同兴趣区的平均弥散系数（ADC）,选择额叶白质、颞叶白质、顶叶白质、枕叶白质、胼胝体膝部、胼胝体压部5个兴趣区,定量测量ADC值。结果老年痴呆组ADC值与对照组比较,在额叶白质(ADC：t=-0.050,p<0.01)、胼胝体膝部(ADC：t=-0.012,p>O.05)、胼胝体压部(ADC：t=-0.028,p<0.05)、颞叶(ADC：t=-0.062,p<0.01)、顶叶(ADC：t=-0.057,p<0.01)、枕叶(ADC：t=0.000,p>0.05)。老年痴呆组顶叶白质、胼胝体压部、额叶白质的ADC值与简易智能精神状态量表(MMSE)相关,尤其是顶叶白质的ADC值相关更显著(r=-0.867,p<0.01)。结论 老年痴呆的定量DWI分析,有助于评价AD常规MRI检查正常区域的微结构改变。顶叶脑白质ADC值的异常在认知功能损害早期更明显,DWI功能与结构的结合,表明老年痴呆认知功能的衰退与白质微结构密切相关。     

弥散张量纤维束成像在脑梗死中的应用

目的探讨弥散张量纤维束成像在脑梗死中的应用。方法 2010年3月至2012年3月份收治脑梗死148例,进行磁共振成像系统重建三维弥散张量纤维束成像图,观察白质纤维束损伤情况,对各组病例进行测量ADVAv值、FA值,并与健侧相应区进行比较。结果急性期48例中,白质纤维束变形移位18例;亚急性期71例,白质纤维束变形移位48例;慢性期29例,白质纤维束变形移位20例。结论通过常规MRI、弥散加权成像和弥散张量纤维束成像进行充分结合对脑梗死进行诊断,对病灶定位更准确,对白质纤维束损伤程度充分判断,通过对平均表观弥散系数、各向异性分数值观察能够对脑梗死更精确的临床分期。     

部分脑白质微结构与帕金森病并发认知障碍的相关性分析

目的 探讨额叶白质、上纵束、扣带前束及扣带后束脑白质微结构与帕金森病并发认知障碍的相关性.方法 根据蒙特利尔认知评估量表（MOCA）将76例帕金森病患者分成并发认知障碍组（PDD组）48例和未并发认知障碍组（PD-CogNL组）28例,另选取30例健康者为对照组.分别测量3组额叶白质、上纵束、扣带前束及扣带后束的FA值.结果 PD-CogNL组额叶白质FA值及扣带前束FA值显著低于对照组,PDD组额叶白质FA值及扣带前束FA值显著低于对照组及PDD组,差异均有统计学意义（P＜0.05）.3组上纵束FA值和扣带后束FA值比较差异无统计学意义（P＞0.05）.结论 帕金森病患者并发认知障碍与额叶白质、扣带前束微脑白质结构的改变具有显著关系,其中与扣带前束相关性最加显著,由此通过测定帕金森病患者脑白质微结构的改变来评定其并发认知障碍的程度.     

磁共振弥散张量成像及白质纤维素追踪成像在缺氧缺血性脑病后遗症期的初步研究

目的探讨磁共振弥散张量成像(DTI)及白质纤维素追踪成像(FT)在随访缺氧缺血性脑损伤后脑内主要白质纤维束变化方面的应用价值。方法对60例缺氧缺血性脑病(HIE)后遗症期婴幼儿(18～36个月)进行DTI检查,并根据方向编码彩色图(DEC图)及部分各向异性图(FA)进行纤维束追踪成像,依据新生儿期初查时临床表现分为轻度、中度和重度三组,与智力发育指数(MDI)和心理运动发育指数(PDI)指数进行相关性分析。结果HIE程度越重,三维彩色编码张量图上颜色越混杂,白质束纤维成像显示纤维越稀疏,MDI和PDI指数越低,呈负相关。结论DTI及FT在评价缺氧缺血性脑损伤后遗症期患儿脑内主要白质纤维束变化方面有较高的应用价值,三维编码彩色张量图及白质束成像可无创性显示脑白质中纤维束的方向、走行和形态,HIE的轻、中、重程度与MDI、PDI有较好的相关性。     

Cortical white matter microstructural abnormalities in bipolar disorder.

This article reports on preliminary findings describing microstructural abnormalities in the white matter of cortical areas thought to be associated with bipolar disorder. In all, 14 patients with bipolar disorder and 21 nonpsychiatrically ill control subjects underwent MR imaging including a diffusion tensor imaging (DTI) pulse sequence (six directions, b=1000 mm(2)/s). DTI data were analyzed on a workstation using a program that allowed calculation of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) within the following three white matter fiber tracts bilaterally: the orbital frontal cortex, and the superior and middle frontal gyri. These values were compared across patient groups. The left and right orbital frontal white matter exhibited significantly higher ADC values in bipolar subjects than control subjects on both the left (p=0.028) and right (p=0.011). Microstructural changes in the white matter of the orbital frontal areas as reflected by increased ADC values appear to be associated with bipolar disorder. Further research is needed to better understand the interaction of microstructural changes and bipolar symptoms and whether these changes are specific to bipolar disorder.     

Disruption of brain white matter microstructure by excessive intracellular and extracellular fluid in alcoholism: evidence from diffusion tensor imaging.

Magnetic resonance diffusion tensor imaging (DTI) has revealed the disruption of brain white matter microstructure in normal aging and alcoholism undetectable with conventional structural MR imaging. The metrics of DTI can be useful in establishing the nature of the observed microstructural aberrations. Abnormally low fractional anisotropy (FA), a measure of diffusion orientation and coherence, may result from increased intracellular or extracellular fluid, which would be reflected in complementary high apparent diffusion coefficients (bulk mean diffusivity) and low FA, or from disorganization of fiber structure, which would be reflected in low FA but with a lack of the inverse FA and diffusivity relationship. To test these competing possibilities, we examined 15 alcoholic men and 31 control men with DTI to quantify diffusivity in the genu and splenium of the corpus callosum and centrum semiovale. In addition to the previously observed FA deficits in all the three brain regions, the alcoholics had abnormally high white matter diffusivity values in the genu and centrum. Further, inverse correlations between FA and diffusivity were significant in the genu (r=-0.52, p<0.05) and centrum (r=-0.92, p=0.0001). Multiple regression analyses examining diffusivity and age as predictors of FA identified diffusivity as a significant unique contributor to FA in both regions. These results suggest that decreased orientational coherence of brain white matter in alcoholism is attributable, at least in part, to the accumulation of intracellular and extracellular fluid in excess of that occurring in aging, and that the differential influence of these fluid compartments can vary across brain regions.     

不同年龄人群脑白质纤维弥散张量成像研究

目的应用磁共振（纤维）弥散张量成像（DTI）技术对不同年龄人群正常脑白质纤维进行研究,探讨其变化规律。方法将40名健康志愿者按年龄分为青年组及老年组各20名进行3．0T磁共振DTI扫描,对比分析其各向异性分数（FA）值变化规律。结果老年组部分脑区域FA值明显低于青年组。结论老年人脑白质纤维完整性较青年人有较为明显的降低,对疾病患者脑白质纤维完整性进行研究的同时要注意年龄的影响因素。     

Brain macrostructural and microstructural abnormalities in cocaine dependence

RATIONALE: Two previous studies have utilized diffusion tensor imaging (DTI) to examine microstructural integrity in cocaine abuse and found evidence of brain abnormalities in white matter. OBJECTIVE: Using anatomical magnetic resonance imaging (MRI), DTI, and clinical evaluation, the macrostructural and microstructural correlates of cocaine abuse were investigated. METHODS: Twenty-one men and women (mean age 42.5 and mean 18.9 years of cocaine use) and 21 age/gender-matched controls were included. Fractional anisotropy (FA) was measured in frontal white matter ROIs. Gray and white matter volumes in superior and inferior frontal regions were compared. RESULTS: DTI data revealed that cocaine users had lower FA than controls, specifically in inferior frontal white matter. FA differences were not seen in other areas. Significant volumetric differences were not seen, but both gray and white matter inferior frontal volumes trended toward smaller in the cocaine group. The data suggested that duration of use was associated with decreased gray and white matter volumes. FA and gray matter volume were correlated in cocaine users. CONCLUSIONS: Both macrostructural and microstructural abnormalities were seen in a group of cocaine abusers. Length of cocaine use was associated with severity of the brain abnormalities. Future studies of white matter tissue integrity are warranted including examination of the relationship between DTI measures and traditional volumetric measures.     

Greater Than Age-Related Changes in Brain Diffusion of HIV Patients After 1 Year

Chronic infection with HIV is associated with neuroinflammation. Prior diffusion tensor imaging (DTI) studies demonstrated increased mean diffusion (MD) and decreased fractional anisotropy (FA) in the white matter (WM) and subcortical brain regions of HIV patients. The current study aims to detect whether there are greater than age-related brain changes in HIV patients after a 1-year follow-up period using DTI. Thirty-nine antiretroviral-stable HIV subjects and 32 HIV-seronegative (SN) controls were evaluated, with neuropsychological tests and DTI, at baseline and after 1 year. MD and FA in the genu and splenium of the corpus callosum and in six other subcortical and white matter regions were evaluated bilaterally. Compared to SN controls, HIV subjects had significantly higher MD in the frontal WM (p = 0.0104) and lower FA in the parietal WM (p = 0.006). After 1 year, HIV subjects showed increase in MD in frontal and parietal WM, putamen, and genu; HIV subjects also showed greater increased genu diffusion than SN controls (p = 0.005). Changes in global cognitive deficit score correlated with changes in MD in the genu and FA in the parietal and frontal WM and putamen (multiple regression, p = 0.0008). Lastly, normal age-dependent changes in frontal WM diffusion and FA in genu and putamen were not observed in HIV subjects. Since increased MD may reflect increased neuroinflammation, our findings suggest greater than normal age-related inflammatory changes in the genu of these HIV patients, which may contribute to the cognitive deficits. Measurements of MD in the genu may be useful for monitoring disease progression in HIV brain infection.     

Brain Microstructure and Impulsivity Differ between Current and Past Methamphetamine Users

Methamphetamine (Meth) use disorder continues to be highly prevalent worldwide. Meth users have higher impulsivity and brain abnormalities that may be different between current and past Meth users. The current study assessed impulsivity and depressive symptoms in 94 participants (27 current Meth users, 32 past Meth users and 35 non-drug user controls). Additionally, brain microstructure was assessed using diffusion tensor imaging (DTI); fractional anisotropy (FA) and mean diffusivity (MD) were assessed in the striatum, and FA, MD, radial and axial diffusivity were quantified in five white matter structures using DtiStudio.Across the three subject groups, current users had the highest self-reported impulsivity scores, while both Meth user groups had larger striatal structures than the controls. Past Meth users had the highest FA and lowest MD in the striatum, which is likely due to greater magnetic susceptibility from higher iron content and greater dendritic spine density. In white matter tracts, current Meth users had higher AD than past users, indicating greater water diffusion along the axons, and suggesting inflammation with axonal swelling. In contrast, past users had the lowest AD, indicating more restricted diffusion, which might have resulted from reactive gliosis. Although current Meth users had greater impulsivity than past users, the brain microstructural abnormalities showed differences that may reflect different stages of neuroinflammation or iron-induced neurodegeneration. Combining current and past Meth users may lead to greater variability in studies of Meth users. Longitudinal studies are needed to further evaluate the relationship between recency of Meth use and brain microstructure.     

Treatment Outcome-Related White Matter Differences in Veterans with Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is a debilitating disorder that has been associated with brain abnormalities, including white matter alterations. However, little is known about the effect of treatment on these brain alterations. To investigate the course of white matter alterations in PTSD, we used a longitudinal design investigating treatment effects on white matter integrity using diffusion tensor imaging (DTI). Diffusion tensor and magnetization transfer images were obtained pre- and posttreatment from veterans with (n=39) and without PTSD (n=22). After treatment, 16 PTSD patients were remitted, and 23 had persistent PTSD based on PTSD diagnosis. The dorsal and hippocampal cingulum bundle, stria terminalis, and fornix were investigated as regions of interest. Exploratory whole-brain analyses were also performed. Groups were compared with repeated-measures ANOVA for fractional anisotropy (FA), and magnetization transfer ratio. Persistently symptomatic PTSD patients had increasing FA of the dorsal cingulum over time, and at reassessment these FA values were higher than both combat controls and the remitted PTSD group. Group-by-time interactions for FA were found in the hippocampal cingulum, fornix, and stria terminalis, posterior corona radiata, and superior longitudinal fasciculus. Our results indicate that higher FA of the dorsal cingulum bundle may be an acquired feature of persistent PTSD that develops over time. Furthermore, treatment might have differential effects on the hippocampal cingulum, fornix, stria terminalis, posterior corona radiata, and superior longitudinal fasciculus in remitted vs persistent PTSD patients. This study contributes to a better understanding of the neural underpinnings of PTSD treatment outcome.