弥散张量成像技术初步评价视放射

目的探索临床可接受的视放射成像扫描计划和相应图像后处理方法。方法对10例正常自愿者(男6例,女4例),年龄20～45岁,平均28岁,以1.5T磁共振扫描仪行DTI扫描,弥散梯度磁场(MPG)选择6、14、323个方向,扫描时间5分钟左右。利用DTI Studio软件,采用多感兴趣区(ROI)法进行图像后处理,重建视放射纤维束,比较三组图像信噪比(SNR)、视放射迈耶袢显示情况以及图像视放射纤维束平均长度与密度。结果三组图像比较,SNR组间差异无统计学意义;6MPG与32MPG组间在迈耶袢显示方面差异有统计学意义。研究三组资料间两两比较,平均纤维束长度与密度的差异均具有统计学意义。结论在1.5T场强、32MPG下、约5分钟扫描时间内,采用多ROI后处理方法,可以得到临床较为满意的视放射纤维束图像。     

多发性硬化患者胼胝体的弥散张量纤维束成像定量研究

目的利用弥散张量纤维束成像(DTT)定量研究多发性硬化(MS)患者胼胝体分数各向异性(FA)值与正常志愿者之间的差异及与扩展病残状态评分(EDSS)的相关性,以明确该指标在多发性硬化研究中的价值.方法对36例正常志愿者和64例复发好转型(RR)MS患者进行弥散张量成像检查,重建出胼胝体并计算出该纤维束的FA值,比较MS组与对照组之间是否存在差异,研究该指标与EDSS的相关性.结果正常志愿者胼胝体FA值无性别差异(P＞0.05),平均FA值为0.506±0.020.MS患者胼胝体平均FA值(0.465±0.033)明显低于(P＜0.01)对照组(0.506±0.020).脑型MS胼胝体平均FA值(0.456±0.036)明显低于脊髓型(0.475±0.025)(P＜0.05).MS患者胼胝体FA值与EDSS评分无显著相关性(r=-0.104,P＞0.05).结论MS患者胼胝体的FA值存在明显异常,但该指标不能反映患者的身体残疾状态.     

磁共振弥散张量成像观察创伤性胼胝体损伤

目的 探讨磁共振弥散张量成像对胼胝体损伤的潜在诊断价值.方法 应用磁共振弥散张量成像技术对25例闭合性颅脑损伤患者及20例健康志愿者进行观察,对胼胝体膝部、压部进行定量测定FA及ADC值,测定结果与患者组GCS进行相关分析.结果 患者组胼胝体膝部及压部的FA值较对照组显著下降(P＜0.05).患者组与对照组所测胼胝体ADC值差异无统计学意义(P＞0.05).患者组胼胝体FA值与GCS呈显著相关(P＜0.05).结论 磁共振弥散张量成像技术能清晰显示并定量与临床GCS评分密切相关的胼胝体损伤,为临床诊断及治疗提供有价值的更深层次的信息.     

心血管磁共振弥散张量成像及弥散频谱成像研究进展

心血管磁共振(cardiovascular magnetic resonance,CMR)多种成像技术可以观察心脏结构功能、心肌组织特征乃至能量代谢.包括弥散加权成像(diffusion weighted imaging,DWI)、弥散张量成像(diffusion tensor imaging,DTI)及弥散频谱成像(diffusion spectrum magnetic resonance imaging,DSI)在内的弥散成像技术一直是CMR最具挑战性及目前尚未常规成熟开展的检查技术,尤以DTI及DSI为甚.本综述将重点阐述DTI及DSI的基本技术及近年来在心血管领域的应用进展.     

正常成人弥散张量成像FA图模板的制作

目的制作正常成人弥散张量成像FA模板并对其进行初步检测.方法对25位正常志愿者进行了弥散张量成像扫描,以SPM99对ADC和FA图进行头颅标准化,并生成FA图的均值图模板和均值加减2倍标准差图模板;随机抽取15位志愿者标准化后的FA图检测均值减2倍标准差图模板.结果将ADC图的头颅标准化参数用于FA图,可以得到很好的标准化效果.制作出来的FA模板经过测试,平均假阳性区域数目为44个,假阳性区域的平均体素为14.3,平均FA差值为0.133,平均假阳性率为0.130%.结论 FA图模板可以达到临床应用要求,用于白质异常区域的检测将极具潜力.     

磁共振弥散张量成像及纤维束成像对脑胶质瘤分级的诊断价值

目的 联合应用弥散张量成像(diffusion tensor imaging,DTI)与弥散张量纤维束成像(diffusion tensor tractography,DTT),探讨其在胶质瘤分级诊断中的应用价值.方法 25例脑胶质瘤患者进行常规MR及弥散张量成像,经组织病理学证实其中9例低级别(Ⅰ～Ⅱ级)胶质瘤,16...     

MR弥散张量成像在中枢神经系统的临床应用

DWI是一种较新的MR成像技术,图像对比与组织内水分子运动的不同有关,水分子的运动用表观扩散系数表示,DWI对急性脑缺血的早期诊断有重要的临床价值;DTI可用于评估各向同性及各向异性扩散.DTI主要用于评估影响脑白质尤其是白质纤维束完整性的疾病.本文主要对DWI、尤其是DTI在中枢神经系统中的临床应用现状作一综述.     

磁共振弥散张量成像在儿童脑发育迟缓的临床研究

目的:探讨磁共振弥散张量成像(DTI)在儿童脑发育迟缓的检测价值。方法:以100例发育迟缓患儿为对象,以同期100例神经系统查体阴性在我院行颅脑MRI检查的发育正常儿童为对照组。均接受DTI检查,对比两组儿童均扩散率(MD)值、部分各向异性(FA)值。结果:发育迟缓组额叶、颞叶、枕叶、半卵圆中心MD值高于对照组(P<0.05)。两组脑白质胼胝体膝部、胼胝体压部、内囊后肢、内囊前肢、视放射FA值比较无差异(P>0.05);发育迟缓组额叶、颞叶、枕叶、半卵圆中心FA值低于对照组(P<0.05)。结论:DTI检查显示发育迟缓儿童脑白质浅部FA值低于正常儿童,MD值高于正常儿童。     

磁共振弥散张量成像对脑出血的临床应用

脑出血是常见病,病死率与致残率均较高。本文主要讨论磁共振弥散张量成像技术对脑出血的临床应用价值研究,以及它的局限性及前景展望。     

弥散加权成像、弥散张量成像及磁共振波谱对脑梗死患者的临床诊断价值分析

目的探讨弥散加权成像、弥散张量成像及磁共振波谱对脑梗死患者的临床诊断价值。方法对87例不同时期脑梗死患者行弥散加权成像(DWI)和磁共振波谱(MRI)检查,测量脑梗死灶的rADC值与ADC值。结果DWI对6h以内脑梗死的检出率显著优于MRI;超急性期与急性期ADC值比较差异无统计学意义(P0.05);病变边缘rADC值和ADC值显著高于病灶中心,差异有统计学意义(P0.05);亚急性期和慢性期与超急性期和急性期rADC值比较差异有统计学意义(P0.05);本研究32例急性期脑梗死死区与健侧对应区的FA平均值分别为(0.24±0.13)与(0.51±0.17),差异有统计学意义(P0.05)。结论随着病变的进展,脑梗死不同时期rADC值与ADC值呈上升趋势,DWI与MRI联合应用对脑梗死病灶给予分期具有重要的价值,DWI、弥散张量成像、MRS三者应用可为治疗脑梗死提供一定的科学依据,值得进一步推广应用。     

脑白质病变患者脑结构网络小世界属性与认知功能障碍关系的弥散张量成像研究

目的 明确脑白质病变(WMLs)患者脑结构网络小世界网络属性与认知功能障碍的关系。     

定量DTI在儿童脑室周白质损伤所致脑瘫中的应用

【目的】运用扩散张量成像（DTI）技术,评价脑室周脑白质损伤患儿脑白质和深部灰质的扩散特性。【方法】采用配对设计方法,对25例脑室周脑白质损伤患儿和25例正常儿童进行常规MRI和DTI检查。用Functool2和DTIStudio软件处理原始图像,得到DTI图像。分析大脑、脑干不同脑白质区域及丘脑、豆状核、尾状核头部深部灰质核团感兴趣区（ROD的平均扩散率（MD）和部分各向异性值（FA）。采用配对资料t检验统计方法检验患儿组与对照组的MD和FA有无显著性差异。【结果】与对照组相比,怠儿组脑白质损伤病灶的ROI测量显示MD显著升高和FA显著下降,患儿组锥体束内囊后肢层面FA减低具有统计学意义,患儿组深部灰质核团MD和FA差异无统计学意义。【结论】不同区域运动通路的变性,在脑室周脑白质损伤患儿的病理生理学机制中发挥重要作用。     

White Matter Structural Differences in Young Children With Type 1 Diabetes: A Diffusion Tensor Imaging Study

OBJECTIVE

To detect clinical correlates of cognitive abilities and white matter (WM) microstructural changes using diffusion tensor imaging (DTI) in young children with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Children, ages 3 to <10 years, with type 1 diabetes (n = 22) and age- and sex-matched healthy control subjects (n = 14) completed neurocognitive testing and DTI scans.

RESULTS

Compared with healthy controls, children with type 1 diabetes had lower axial diffusivity (AD) values (P = 0.046) in the temporal and parietal lobe regions. There were no significant differences between groups in fractional anisotropy and radial diffusivity (RD). Within the diabetes group, there was a significant, positive correlation between time-weighted HbA_1c and RD (P = 0.028). A higher, time-weighted HbA_1c value was significantly correlated with lower overall intellectual functioning measured by the full-scale intelligence quotient (P = 0.03).

CONCLUSIONS

Children with type 1 diabetes had significantly different WM structure (as measured by AD) when compared with controls. In addition, WM structural differences (as measured by RD) were significantly correlated with their HbA_1c values. Additional studies are needed to determine if WM microstructural differences in young children with type 1 diabetes predict future neurocognitive outcome.Children diagnosed with the onset of type 1 diabetes before 5 years of age have impaired performance in memory, attention, visual-perceptual function, and fine motor speed/coordination (1,2). Young children with type 1 diabetes have the greatest excursions in blood glucose (BG) values (3) because of their irregular eating patterns and inability to recognize and report symptoms of hypoglycemia or hyperglycemia. Both hypoglycemia (4,5) and hyperglycemia (6,7) have been associated with neurocognitive effects and brain volume differences (8). Early childhood is a period of rapid and dynamic changes in the central nervous system, such as myelination, modification of synapses, and pruning. Therefore, during this time of potential increased vulnerability to central nervous system insults (9,10), increased occurrences of glycemic excursions may lead to neurocognitive deficits (11). Although there have been concerns regarding how type 1 diabetes and its treatment impact cognitive performance and brain structure, neither the extent of this impact nor the putative mechanisms have been elucidated.The white matter (WM) of the brain consists mostly of myelinated neuronal axons responsible for signal transfer between neuronal cells. We previously reported (12) no significant differences in total gray matter (GM) and WM volumes between children (3–10 years of age) with type 1 diabetes and healthy controls. However, regional differences in brain structure or function that could lead to undesirable behavioral and cognitive outcome have not been adequately evaluated in this young age group.Diffusion tensor imaging (DTI) is a noninvasive magnetic resonance imaging (MRI)–based method that uses the diffusion of water molecules in the brain to investigate WM structure. To date, DTI has been used for the investigation of WM structure in adults with type 1 diabetes, but not in children. Kodl et al. (13) investigated adults with long-standing type 1 diabetes and found microstructural abnormalities in several WM tracts, including the posterior corona radiate and optic radiations. Further, WM structural variations observed with DTI in adult subjects with type 1 diabetes were correlated with poorer performance on the Rey-Osterreith Complex Figure Drawing and Grooved Peg Board tests (13). Using the same sample, Franc et al. showed a correlation between the WM tracts previously found to have reduced fractional anisotropy (FA) and regions with reduced cortical thickness (14). Together, these findings suggest that long-standing type 1 diabetes causes widespread microstructural WM alterations in the posterior cerebrum.With no published DTI studies in children with type 1 diabetes, it is not known if and when putative insults to developing WM structure occur. We hypothesized that WM structure would be different in young children with type 1 diabetes when compared with matched healthy control subjects.     

精神分裂症患者的扩散张量成像与认知功能相关性研究

目的：了解精神分裂症（SCZ）患者的脑白质损害的特点及其与临床症状、认知功能损害之间的关 系。方法：招募精神分裂症患者（SCZ 组）及健康对照（HC 组）各 30 例,对 2 组进行磁共振扩散张量成像 （DTI）扫描,及临床症状评定、SCZ认知功能简明评测量表（BACS）测评;采用优化的空间统计方法（TBSS） 对DTI数据进行分析,分析两组之间DTI扫描结果的差异及其与临床症状、BACS得分的相关性。结果： SCZ 组全脑多处纤维束 FA 值低于对照组（P＜0.05）;左侧小脑上脚 FA 值与符号编码得分呈正相关（r= 0.384,P=0.039）。结论：SCZ患者存在全脑多处白质纤维损害,且部分重要白质纤维损害与认知障碍存在 相关性。     

弥散张量成像技术在评估脑卒中患者白质纤维束损伤及预后方面的研究进展

弥散张量成像(DTI)技术利用组织中水分子的自由热运动的各向异性的原理,并通过特殊的软件处理成像,对大脑白质纤维束的三维几何结构进行研究,重建脑部白质神经连接,可直观地显示脑内病变对白质纤维形态结构直接或间接的影响。本文对DTI在脑卒中患者白质纤维束损伤及预后评估中的研究进展进行综述。     

脑干白质纤维束磁共振扩散张量成像研究

目的：使用磁共振扩散张量成像方法对脑干白质束进行研究。方法：30名健康志愿者进行MR检查，检查包括常规T1WI，T2WI以及扩散张量序列。结果：在脑干不同解剖水平，锥体束、锥体交叉、内、外侧丘系在各向异性（FA）图像上均显示为高信号，在彩色张量图像上分别显示为红色（横向走行）、蓝色（上下走行）和绿色（前后走行）的纤维束，而这些结构在常规T1WI、T2WI上均不能得到显示。结论：扩散张量成像可以无创性检查脑干白质束。