皮质下缺血性血管性痴呆患者脑白质损害的磁共振弥散张量成像研究

目的:应用磁共振弥散张量成像技术(DTI)观察皮质下缺血性血管性痴呆(SIVD)患者脑白质损害程度,探讨DTI对SIVD白质损害的评估及与阿尔茨海默病(AD)鉴别诊断价值。方法:研究对象分为3组,分别是健康老年人(NC)、皮质下缺血性血管性痴呆(SIVD)患者、AD患者,每组各20例。行常规MR I和DTI扫描后,测定相同感兴趣区(RO I)的各向异性分数(FA)值和表观扩散系数(ADC)值进行比较。结果:SIVD组下额枕束、胼胝体膝部、胼胝体压部、上纵束等部位FA值下降,ADC值升高,与NC、AD组比较差异有统计学意义(P<0.05)。与NC组比较,AD组前额叶、颞叶、海马、下额枕束、胼胝体膝部和扣带束等部位FA值降低,颞叶、海马等部位ADC值升高,两组差异具有显著性(P<0.05);结论:DTI可以用来评估痴呆患者白质损害的程度,SIVD患者以下额枕束、胼胝体膝部、胼胝体压部、上纵束等部位受累为主,可作为与AD鉴别的客观指标。     

弥散张量成像在非痴呆帕金森病认知障碍患者中的应用

目的探讨帕金森病的轻度认知障碍(PD-MCI)与各脑白质分区微结构改变的关系。方法选择40例帕金森病(PD)患者作为研究对象,其中认知正常组(PD-CogNL)和轻度认知障碍组(PD-MCI组)各20例,另选20例健康志愿者作为对照组,行蒙特利尔认知评估量表(MoCA)评估其认知功能;DTI检查测定脑部50个脑白质分区的微观结构改变。对三组研究对象的MoCA量表得分及其中7个认知阈检查分别进行方差分析,测定50个的分数各向异性(fFA)值,三组之间FA值行方差分析。最后,将PD-MCI组的MoCA量表评分与选定的23个脑区的FA值进行Pearson相关性分析。结果(1)在认知阈检查发现视空间与执行功能、注意力两项差异有统计学意义(P0.05);(2)在FA值统计中结果为除穹窿、右皮质脊髓束、左皮质脊髓束、左上放射冠差异无统计学意义(P0.05),其他脑白质分区差异均有统计学意义(P0.05);(3)将具有统计学意义的脑白质分区,在PD-CogNL组和PD-MCI组间进行统计学分析。结果得出23个脑白质分区具有统计学意义(P0.05);在PD-MCI组内将上述脑区的FA值和MoCA进行Pearson相关分析,胼胝体体部、胼胝体压部、左扣带(海马)、左穹窿/终纹、右上额枕束、左下额枕束、左钩束和MoCA得分具有相关性且r为正数,P0.05。结论PD患者轻度认知障碍程度与患者胝体体部、胼胝体压部、左扣带(海马)、左穹窿/终纹、右上额枕束、左下额枕束、左钩束病变严重程度呈正相关,提示这些部位改变可能与PD-MCI患者的认知改变相关,且为进一步研究PD-MCI的病理基础及临床早期诊断提供依据。     

弥散张量磁共振成像在脑实质内肿瘤手术中的作用

目的研究弥散张量磁共振成像(DTI)在认识脑实质内肿瘤的生长方式和显微手术中的作用。方法脑实质内肿瘤患者41例,随机分为对照组23例,研究组18例。手术前、后行常规MR及DTI检查。所有患者手术均在显微操作下进行。两组病例依据不同的影像选择手术入路。比较两组患者手术结果、DTI影像变化以及手术前后神经功能改变。结果21例胶质母细胞瘤和1例室管膜母细胞瘤位于中央区及附近、颢枕部和颞叶深部,术前DTI表现肿瘤仅将传导束推移；2例转移瘤位于颞枕部,术前DTI显示视放射没有解剖移位,而是部分缺如,提示肿瘤对其有侵犯；8例星形或少枝胶质瘤位于额、颞、顶、枕部,术前DTI提示传导束未出现移位、变形,表现为经过肿瘤部位的传导束中断,这说明肿瘤对其侵犯、破坏；其余肿瘤未涉及到重要传导束。术后DTI显示对照组5例患者因手术导致传导束受损,研究组2例损伤。传导束损伤的患者均出现相应的神经功能障碍。结论DTI能够清楚可靠的显示肿瘤与白质传导束的关系,有利于确定手术方案,术中保护功能传导束,提高肿瘤切除率。     

皮质下缺血性血管性痴呆患者大脑联络纤维弥散张量成像研究

目的应用磁共振弥散张量成像(DTI)技术,研究皮质下缺血性血管性痴呆(SIVD)患者脑白质联络纤维变化的特点,以探讨弥散张量成像在诊断SIVD患者中的诊断价值。方法对60例SIVD患者和45例年龄匹配的非痴呆对照者,应用简易智能状态检查量表(MMSE)、蒙特利尔认知测评量表(Mo CA)及临床痴呆量表(CDR)进行认知功能评估;用全脑磁共振DTI技术,测量上纵束、下额枕束(额部、额颞部和颞部)、胼胝体膝部和压部和扣带束多个感兴趣区的各向异性分数(FA)值和表观弥散系数(ADC)值。结果与对照组比较,SIVD组双侧下额枕束、双侧扣带束、左侧上额枕束和胼胝体膝部FA值明显下降,ADC值明显升高,差异有统计学意义(均P<0.05),右侧上额枕束和胼胝体压部的FA值和ADC值差异无统计学意义(P>0.05)。结论 SIVD患者多个感兴趣区的DTI改变证明联络纤维损伤明显;全脑DTI研究是SIVD患者敏感可靠的技术方法,有助于理解SIVD患者的认知功能与联络纤维损害的关系。     

阿尔茨海默病颞干纤维束扩散张量成像研究

目的应用扩散张量成像(DTI)研究阿尔茨海默病和遗忘型轻度认知损害患者白质和颞干纤维束部分各向异性(FA)值变化特点,探讨颞干纤维束损伤机制及其对阿尔茨海默病和遗忘型轻度认知损害的诊断与鉴别诊断价值。方法应用常规MRI和DTI测量阿尔茨海默病(10例)、遗忘型轻度认知损害(10例)和正常对照者(10例)颞干纤维束(包括前连合、钩束、额枕下束)及前额叶、颞叶、顶叶、枕叶白质FA值,比较各组受试者左右侧对称部位白质和颞干纤维束FA值变化。结果各组受试者左右侧对称部位白质和颞干纤维束FA值差异无统计学意义(均P0.05),但其前连合、钩束、额枕下束及前额叶白质FA值差异具有统计学意义(均P0.05)。其中,阿尔茨海默病组前连合、钩束、额枕下束FA值低于遗忘型轻度认知损害组(均P0.05),前连合、钩束、额枕下束及前额叶、顶叶白质FA值低于正常对照组(均P0.05);而遗忘型轻度认知损害组与正常对照组前连合、钩束、额枕下束及前额叶白质FA值差异无统计学意义(均P0.05)。结论阿尔茨海默病和遗忘型轻度认知损害患者与正常老年人颞干纤维束FA值存在显著差异,提示颞干纤维束在阿尔茨海默病患者白质损伤中具有重要意义,DTI检查有助于阿尔茨海默病与遗忘型轻度认知损害和正常老龄化的鉴别诊断。阿尔茨海默病前连合、钩束、额枕下束及前额叶、顶叶白质FA值异常具有良好的临床诊断价值。     

白质纤维束的弥散张量成像在脑胶质瘤外科的应用

目的:探讨MRI弥散张量成像(DTI)显示脑白质纤维束在脑胶质瘤外科的意义。方法:2003年9月至2004年12月,30例脑内肿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,经后处理得到各向异性分数(FA)图显示脑白质纤维束结构,并进行FA值、图像信号强度及对比度的分析研究。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。结论:DTI影像可以清晰显示脑白质纤维束的形态结构。结合其他序列的MRI应用于脑胶质瘤的术前诊断,可以准确判别肿瘤和周围脑白质纤维束的毗邻关系,对脑胶质瘤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。     

磁共振张量成像对脑梗死预后的评价

目的利用磁共振弥散张量成像(DTI)探讨脑梗死病人脑白质纤维束各向异性特征和白质纤维束受损与临床预后关系。方法对23例脑梗死患者行DTI检查,以三维立体弥散张量成像为基础的色彩图进行图像后处理,评价脑梗死区周边纤维束的情况,将纤维束分为受压移位、变细萎缩和破坏中断三类,并与临床预后、神经功能缺损程度比较。结果三维成像所见与病人预后关系密切。所有脑白质纤维束萎缩和中断的患者,在随访过程中存在不同程度脑功能损伤,而脑白质受压移位的病人神经功能完全或近乎完全恢复。结论在脑梗死中,DTI能直接观察到白质纤维束的变化,对于评估临床预后具有重要作用。     

磁共振弥散张量成像对功能区脑肿瘤手术的参考价值

[目的]评价磁共振弥散张量成像(DTI)对功能区脑肿瘤手术的指导意义和应用价值.[方法]对25例患者行头部DTI检查,立体显示肿瘤与脑白质纤维束的关系,术前评估,设计手术入路,对所有病例行显微外科肿瘤切除手术治疗.[结果]本组脑肿瘤中累及脑白质纤维束区域主要位于锥体束和内囊,其中脑白质纤维束破坏13例,移位12例.肿瘤全切除11例,次全切除14例,无手术死亡.术前存在脑白质纤维束受累所致的神经功能阳性体征者术后改善13例,无变化者10例,加重2例.[结论]DTI能够清晰显示脑肿瘤对白质纤维束的累及关系,对神经外科优化手术设计、决定手术切除范围和评估术后神经功能具有指导意义.     

帕金森病合并认知功能障碍与脑白质纤维束改变的关系

目的探讨帕金森病(PD)合并认知功能障碍与认知相关脑白质纤维束改变的关系。方法纳入PD患者35例,根据蒙特利尔认知评估量表(MoCA)评分将PD患者分为PD认知功能正常组(PD-nCI,n=14)和PD认知功能障碍组(PD-CI,n=21);另选择同期行查体的健康志愿者20名作为对照组。所有受试者行弥散张量成像(DTI)检查,通过基于纤维束的空间统计分析(tract-based spatial statistics,TBSS)方法选出与认知相关的脑白质纤维束,并测量各纤维束部分各向异性(fractional anisotropy,FA)值。比较各组不同纤维束FA值差异,采用Pearson相关分析法分析PD-CI组差异有统计学意义的纤维束FA值与MoCA评分的相关性。结果(1)3组间胼胝体膝部、胼胝体体部、胼胝体压部、右扣带回(海马)、左扣带回(海马)、右穹窿/终纹、左穹窿/终纹、右上额枕束、左上额枕束FA值比较存在统计学差异(均P0.05),PD-nCI组和PD-CI组间胼胝体膝部、胼胝体体部、胼胝体压部、右扣带回(海马)、左扣带回(海马)、左穹窿/终纹、右上额枕束、左上额枕束FA值比较存在统计学差异(均P0.05);(2)PD-CI组胼胝体压部、右扣带回(海马)、右上额枕束、左上额枕束FA值与MoCA评分呈正相关(均P0.05)。结论 PD患者认知功能损害程度与胼胝体压部、右扣带回(海马)、右上额枕束和左上额枕束等纤维束病变严重程度呈正相关。     

2型糖尿病合并认知功能障碍患者的脑白质结构变化的影像学特征分析

目的探讨2型糖尿病(T2DM)合并认知功能障碍(T2DM-CI)患者的脑白质结构变化特征。方法纳入33例T2DM-CI患者(T2DM-CI组)、35例T2DM无合并认知功能障碍患者(T2DM-nonCI组)及43例无DM和认知功能障碍者为对照组。应用MR DTI序列检查,利用图集分割的方法计算脑白质20条纤维束弥散参数,比较组间差异,并与认知功能进行相关性分析。结果 3组受试者脑白质纤维束FA值呈下降趋势,MD值呈上升趋势。T2DM-CI组与T2DMnon CI组比较,双侧皮质脊髓束、右侧扣带束海马、胼胝体体部、胼胝体压部、右侧下额枕束、右侧下纵束的FA值差异有显著性(均P 0. 05/20条纤维束)。其中,胼胝体压部、右侧下纵束与语言功能显著相关;双侧皮质脊髓束,胼胝体压部与处理速度差异有显著性(均P 0. 05)。双侧皮质脊髓束、胼胝体压部、双侧下额枕束,双侧上纵束的MD值差异有显著性(均P 0. 05/20条纤维束)。其中,右侧下额枕束、右侧上纵束与语言功能差异有显著性(均P 0. 05)。结论T2DM-CI患者脑白质结构完整性受到破坏,其中胼胝体压部、下纵束、下额枕束、上纵束损伤可能与T2DM-CI患者语言功能受损相关,皮质脊髓束、胼胝体压部损伤可能与处理速度受损相关。     

Diffusion tensor imaging and tractography of central pontine myelinolysis

OBJECTIVES: To illustrate the value of diffusion tensor imaging and tractography in the diagnosis and follow-up of central pontine myelinolysis. CASE REPORT: We report a case of central pontine myelinolysis in a 29 year old woman, also anorexic, studied using MR Diffusion Tensor Imaging (DTI) and Fibre Tracking (FT) focused on the pons, and compared with the studies of 5 normal volunteers. Tractography showed a swollen aspect of the right corticospinal fiber tract correlating with mild left lower extremity deficit at clinical evaluation. The pontine fibers were posteriorly displaced but intact. The sensory tracts were also intact. Apparent Diffusion Coefficient values were increased and Fractional Anisotropy was decreased in the lesions. Follow up imaging showed persistent abnormal ADC and FA values in the pons although the left cortico-spinal tract returned to normal, consistent with the clinical outcome. CONCLUSION: Diffusion Tensor Imaging MR and Fiber tractography are a new method to analyse white matter tracts. It can be used to prospectively evaluate the location of white matter tract lesions at the acute phase of central pontine myelinolysis and follow up.     

Diffusion tensor imaging (DTI) and tractography of the cerebellar projections to prefrontal and posterior parietal cortices: a study at 3T

OBJECTIVES: Previous diffusion tensor imaging (DTI) studies have identified cerebellar pathways and supratentorial connections, but none of them have isolated cerebellar projections to prefrontal and posterior parietal cortices using tractography. The aim of our study was to identify and visualize on 3D projections, as well as on 2D cross-sectional images, the cerebellar projections to prefrontal (PF) and posterior parietal (PP) cortices. MATERIAL AND METHODS: The study included 10 healthy volunteers, four males and six females aged 25 to 45 years (mean age 31 years). A DTI sequence was applied at 3 Tesla using diffusion sensitizing gradients in 32 directions. White matter tracts were reconstructed by applying a multiple ROI (region of interest) tractography technique. RESULTS: PF projections were obtained in all subjects. PP projections were obtained in six over 10 subjects. On 2D cross-sectional images, the tracts showed the same anatomical location in each ROI in all subjects. CONCLUSION: This DTI study at 3T resulted in a selective and full visualization of cerebellar projections to PF and PP cortices for the first time and is introductive for further optimized and quantitative DTI study of these tracts.     

Three-dimensional high-resolution diffusion tensor imaging and tractography of the developing rabbit brain

Diffusion tensor imaging (DTI) is sensitive to structural ordering in brain tissue particularly in the white matter tracts. Diffusion anisotropy changes with disease and also with neural development. We used high-resolution DTI of fixed rabbit brains to study developmental changes in regional diffusion anisotropy and white matter fiber tract development. Imaging was performed on a 4.7-tesla Bruker Biospec Avance scanner using custom-built solenoid coils and DTI was performed at various postnatal ages. Trace apparent diffusion coefficient, fractional diffusion anisotropy maps and fiber tracts were generated and compared across the ages. The brain was highly anisotropic at birth and white matter anisotropy increased with age. Regional DTI tractography of the internal capsule showed refinement in regional tract architecture with maturation. Interestingly, brains with congenital deficiencies of the callosal commissure showed selectively strikingly different fiber architecture compared to age-matched brains. There was also some evidence of subcortical to cortical fiber connectivity. DTI tractography of the anterior and posterior limbs of the internal capsule showed reproducibly coherent fiber tracts corresponding to known corticospinal and corticobulbar tract anatomy. There was some minor interanimal tract variability, but there was remarkable similarity between the tracts in all animals. Therefore, ex vivo DTI tractography is a potentially powerful tool for neuroscience investigations and may also reveal effects (such as fiber tract pruning during development) which may be important targets for in vivo human studies.     

锥体束示踪成像技术在经侧裂岛叶肿瘤切除术中的应用

目的利用锥体束示踪成像技术指导经侧裂岛叶肿瘤切除手术。方法对18例岛叶肿瘤患者行经外侧裂岛叶肿瘤切除手术,分别在术前和术后两次进行磁共振弥散张量成像(diffusion tensor imaging,DTI),并应用白质纤维束示踪技术(fiber tracking)进行DTI原始影像数据后处理,得到锥体束示踪成像(tractography)。观察手术前后锥体束的形态、结构和空间位置的变化,通过测量其连续性、完整性以及空间位移以评估肿瘤占位效应及经侧裂岛叶肿瘤切除术对锥体束的影响。结果18例患者手术均行经侧裂岛叶肿瘤切除术,13例全切除,5例次全切除。手术前后均实现锥体束示踪成像,在锥体束示踪成像上可以精确测定有效锥体束条数。结论锥体束示踪成像可以清晰显示手术前后锥体束的形态、结构和空间位置及受肿瘤推移幅度,可用于指导经侧裂岛叶肿瘤手术的术前计划。     

Diffusion tensor imaging tractography and reliability analysis for limbic and paralimbic white matter tracts

Diffusion tensor imaging (DTI) provides the opportunity to study white matter tracts in vivo. The goal was to estimate the reliability of DTI tractography for the analysis of limbic and paralimbic white matter. Normative data from 24 healthy subjects and reliability data from four healthy and four depressed subjects were acquired at 1.5 Tesla, using twice-refocused spin-echo, echoplanar DTI and Fluid-Attenuated Inversion Recovery (FLAIR) DTI sequences. Fiber tracking was performed using the Fiber Assignment by Continuous Tracking algorithm. Fractional Anisotropy (FA), trace Apparent Diffusion Coefficient and tract volumes were calculated. The inter-rater (and intra-rater) intraclass correlation coefficients for FA values were as follows: rostral cingulum 0.89 (0.87), dorsal cingulum 0.85 (0.90), parahippocampal cingulum 0.85 (0.95), uncinate fasciculus 0.85 (0.87), medial prefrontal white matter 0.97 (0.99), ventromedial prefrontal white matter 0.92 (0.93), crus of fornix 0.80 (0.81). The reported DTI protocol provides a reliable method to analyze limbic and paralimbic white matter tracts relevant to psychiatric disorders.     

Diffusion tensor imaging of white matter and correlates to eye movement control and psychometric testing in children with prenatal alcohol exposure

Prenatal alcohol exposure (PAE) can cause central nervous system dysfunction and widespread structural anomalies as detected by magnetic resonance imaging (MRI). This study focused on diffusion tensor imaging (DTI) of white matter in a large sample of PAE participants that allowed us to examine correlations with behavioral outcomes. Participants were confirmed PAE (n = 69, mean age = 12.5 ± 3.2 years) or typically developing control children (n = 67, mean age = 12.1 ± 3.2 years) who underwent brain MRI, eye movement tasks, and psychometric tests. A semi‐automated tractography method extracted fractional anisotropy (FA) and mean diffusivity (MD) values from 15 white matter tracts. The PAE group displayed decreased FA compared with controls in multiple tracts including 3 corpus callosum regions, right corticospinal tract, and 3 left hemisphere tracts connecting to the frontal lobe (cingulum, uncinate fasciculus, and superior longitudinal fasciculus). Significant group by sex interactions were found for the genu, left superior longitudinal fasciculus, and the left uncinate, with females in the PAE group exhibiting lower FA compared with control females. Correlations were found between DTI and eye movement measures in the control group, but these same relationships were absent in the PAE group. In contrast, no correlations were found between DTI and any of the psychometric tests used in this study. These findings support the hypothesis that measures of eye movement control may be valuable functional biomarkers of the brain injury induced by PAE as these tasks reveal group differences that appear to be linked to deficits in white matter integrity in the brain. Hum Brain Mapp 38:444–456, 2017. © 2016 Wiley Periodicals, Inc.     

Compromised Neurocircuitry in Chronic Blast‐Related Mild Traumatic Brain Injury

The aim of this study was to apply recently developed automated fiber segmentation and quantification methods using diffusion tensor imaging (DTI) and DTI‐based deterministic and probabilistic tractography to access local and global diffusion changes in blast‐induced mild traumatic brain injury (bmTBI). Two hundred and two (202) male active US service members who reported persistent post‐concussion symptoms for more than 6 months after injury were recruited. An additional forty (40) male military controls were included for comparison. DTI results were examined in relation to post‐concussion and post‐traumatic stress disorder (PTSD) symptoms. No significant group difference in DTI metrics was found using voxel‐wise analysis. However, group comparison using tract profile analysis and tract specific analysis, as well as single subject analysis using tract profile analysis revealed the most prominent white matter microstructural injury in chronic bmTBI patients over the frontal fiber tracts, that is, the front‐limbic projection fibers (cingulum bundle, uncinate fasciculus), the fronto‐parieto‐temporal association fibers (superior longitudinal fasciculus), and the fronto‐striatal pathways (anterior thalamic radiation). Effects were noted to be sensitive to the number of previous blast exposures, with a negative association between fractional anisotropy (FA) and time since most severe blast exposure in a subset of the multiple blast‐exposed group. However, these patterns were not observed in the subgroups classified using macrostructural changes (T2 white matter hyperintensities). Moreover, post‐concussion symptoms and PTSD symptoms, as well as neuropsychological function were associated with low FA in the major nodes of compromised neurocircuitry. Hum Brain Mapp 38:352–369, 2017. © 2016 Wiley Periodicals, Inc.     

弥散张量成像在颅脑病变周围水肿带内纤维显示局限性分析

目的探讨弥散张量成像（diffusion tensor imaging,DTI）在颅脑病变周围水肿带纤维显示的局限性。方法对21例脑瘤病人术前均行DTI扫描并以弥散张量纤维束成像（diffusion tensor tractography,DTT）重建颅脑病变周围水肿带纤维,比较所得结果与病人术前症状的符合程度。5例病人术后复查DTI,对比手术前后DTT与病人手术前后症状变化。结果 DTI能无创显示颅内神经纤维的三维走行,但在水肿带纤维显示方面存在一定局限性,主要表现为纤维显示缺失、断裂等,与临床症状不符。结论术前应用DTI技术指导神经外科手术时,应充分考虑到DTI在颅脑病变周围水肿带纤维显示的局限性。应寻求更先进的数据扫描和重建方法真实显现水肿带纤维,更好指导手术。     

Fronto-temporal disconnectivity and clinical short-term outcome in first episode psychosis: A DTI-tractography study

Determining reliable markers of clinical outcome for psychosis is essential to adjust intervention efforts. White matter alterations exist prior to psychosis onset but its association with clinical outcome in the very early phase of psychosis is currently unknown. In the present study, white matter was assessed by diffusion tensor imaging (DTI) in patients with first episode psychosis (FEP) and healthy controls. Forty-four FEP patients and 30 matched healthy controls completed a DTI scan. The patient group was split in poor (n = 24) and good (n = 20) outcome subgroups based on 6-month clinical data. DTI tractography was used to estimate fractional anisotropy (FA) in the three main tracts connecting frontal and temporal regions (i.e. the cingulum, the superior longitudinal fasciculus and the uncinate fasciculus). The analyses showed selective FA reductions in both the uncinate and the superior longitudinal fasciculi, but not in the cingulum, when comparing FEP patients to healthy controls. FEP subgroup analyses revealed greater white matter changes in these tracts in patients with poor outcome as compared to patients with good outcome. These findings confirm that abnormal fronto-temporal connectivity contributes to the physiopathology of FEP and constitutes an early marker of clinical short-term outcome.