运用DTI直方图分析血管性认知功能障碍患者正常表现白质损害与认知功能的关系

目的 利用扩散张量成像(DTI)直方图分析,明确血管性认知功能障碍(VCI)患者的正常表现脑白质(NAWH)损害与认知功能之间的关系.资料与方法 对24例VCI患者、18例卒中后无认知功能损害患者(Stroke组)行常规MRI和DTI检查,各组之间性别、年龄和受教育程度相匹配.计算侧脑室旁高信号灶评分(PVH)和深部白质病变评分(DWMH score)、病变体积与颅脑内容积的比值、灰质(GM)、白质(WM)、表现正常灰质(NAGM)、NAWM的各向异性分数(FA)和表观扩散系数(ADC)图.结果 VCI患者的FA和ADC直方图与Stroke组不同,VCI患者WM及NAWH FA直方图左移、FA峰高增高;ADC直方图右移、峰高降低.两组之间FA值在WM平均值、WM峰位置、NAWM平均值和NAWM峰高存在差异,而ADC值在WM平均值、WM峰位置和NAWM平均值存在差异(P<0.01).VCI患者NAWH的FA平均值和峰高与言语流畅性测验(VFT)评分存在相关性(P<0.05).结论 VCI患者NAWH存在病变,其病变的严重程度与认知功能损害程度有关,DTI直方图分析可用于评价疾病的严重程度.     

临床孤立综合征和复发缓解型多发性硬化患者表现正常脑白质及脑灰质的MR扩散张量直方图比较

目的 评价扩散张量成像(DTI)对临床孤立综合征(CIS)的研究价值,了解CIS的病理变化机制及与复发缓解型多发性硬化(RRMS)的关系.方法 选择19例CIS患者(CIS组)、19例RRMS患者(RRMS组)和19例性别、年龄与之匹配的健康志愿者(正常对照组)为研究对象.用1.5 T超导型MR机采集数据,经图像后处理得到表现正常脑白质(NAWM),表现正常脑灰质(NAGM)的平均扩散率(MD)、各向异性分数(FA)直方图,其中提取出下列指标:平均值、直方图峰高和峰位置,进行单因素方差分析和秩和检验,并对3组NAWM、NAGM的MD、FA值与扩展残疾状态量表(EDSS)评分进行Spearman相关分析.结果 RRMS组患者表现正常脑白质MD为(0.83±0.04)×10-3mm2/s,较正常对照组(0.78±0.02)×10-3mm2/s、CIS组(0.79±0.02)×10-3mm2/s均显著增高(F=15.304,P＜0.01),但CIS组与正常对照组间差异无统计学意义(P＞0.05);MD图峰高CIS组明显低于正常对照组(P＜0.01);RRMS组平均FA值(0.36±0.03)较正常对照组(0.41±0.01)及CIS组(0.40±0.02)均降低(F=17.965,P＜0.01),但CIS组与正常对照组间差异无统计学意义(P＞0.05),平均FA图峰位置CIS组较正常对照组明显左移.NAGM MD在正常对照组、CIS组、RRMS组分别为(1.03±0.05)、(1.08±0.06)、(1.18±0.12)×10-3mm2/s,依次增高,且差异均有统计学意义(F=15.261,P＜0.01).CIS患者的各项DTI指标与EDSS评分均无显著性相关.RRMS患者NAGM的MD与EDSS评分呈正相关(r=0.568,P＜0.05).结论 DTI直方图可以敏感的显示及量化CIS及多发性硬化(MS)NAWM、NAGM的异常,作为MS最早期表现的CIS患者NAWM、NAGM均已发生了病理改变,但较MS病变轻.     

MRS联合DTI技术在多发性硬化中的初步应用

目的 探讨磁共振波谱(MRS)联合扩散张量成像(DTI)技术在多发性硬化(MS)中的应用价值.资料与方法 26例MS患者和16名性别、年龄相匹配的健康志愿者均进行半卵圆中心层面的多体素MRS扫描和全脑的DTI扫描.分别测量MS患者的额叶病灶区、对侧正常表现的脑白质区(NAWM)以及对照组的双侧额叶对应脑白质区的NAA/Cr、Chow/Cr和表观扩散系数(ADC)、各向异性(FA)值.比较三组之间MRS代谢物比值和DTI的参数之间是否存在相性.结果 NAA/Cr在MS的病灶组(1.617±0.336)、NAWM组(1.809±0.339)中均明显低于正常对照组(2.103±0.245);Chow/Cr在病灶和NAWM内可见轻度升高,但与正常人比较未见明显的统计学差异.在MS病灶内,NAA/Cr与ADC(r=-0.575,P=0.002)和FA(r=0.479,P=0.013)呈明显相.结论 MRS联合DTI技术能同时发现MS病灶的轴索损伤和髓鞘脱失,在反映MS的病理变化和探讨病理机制方面可提供有价值的信息.     

DTI Study of Relationship between Infarction Damage as well as Hippocampal Secondary Degeneration and Cognitive Disorder in Chronic MCAO Patients

目的 应用扩散张量成像(diffusion tensor imaging,DTI)检测脑梗死慢性期患者脑梗死灶的改变和海马的继发性改变,并分析其与认知功能的关系.资料与方法 选取40例病程半年以上的单侧仅大脑中动脉供血区脑梗死(middle cerebral artery occlusion,MCAO)患者及40名与其性别、年龄、文化程度相匹配的正常志愿者于1.5T磁共振扫描仪行全颅15个方向的DTI检查.采用手工法在脑梗死灶及对侧脑组织和双侧海马选取不同兴趣区(region of interest,ROI)进行测量得到各向异性分数(fractional anisotropy,FA)及表观扩散系数(apparent diffusion coefficient,ADC)值.结果 慢性期单侧MCAO患者脑梗死灶及脑梗死同侧海马较对侧相应部位FA值均降低,脑梗死灶FA值降低49.8％,脑梗死同侧海马FA值降低9.29％,ADC值均升高,脑梗死灶ADC值升高132.75％,脑梗死同侧海马ADC值升高4.9％.脑梗死灶ADC值改变率(rADC)较FA值改变率(rFA)明显,而海马rFA较rADC明显,并且脑梗死灶的rFA与认知功能存在相关性,相关系数为-0.41.结论 DTI技术可以用来定量评价慢性期脑梗死患者脑梗死灶及海马的改变,并且慢性期脑梗死患者脑梗死灶rFA与认知功能存在相关性.     

慢性期MCAO患者脑梗死灶扩散变化及海马继发改变与认知功能关系的DTI研究

目的应用扩散张量成像(diffusion tensor imaging,DTI)检测脑梗死慢性期患者脑梗死灶的改变和海马的继发性改变,并分析其与认知功能的关系。资料与方法选取40例病程半年以上的单侧仅大脑中动脉供血区脑梗死(middle cerebral artery occlusion,MCAO)患者及40名与其性别、年龄、文化程度相匹配的正常志愿者于1.5T磁共振扫描仪行全颅15个方向的DTI检查。采用手工法在脑梗死灶及对侧脑组织和双侧海马选取不同兴趣区(region of interest,ROI)进行测量得到各向异性分数(fractional anisotropy,FA)及表观扩散系数(apparent diffusion co-efficient,ADC)值。结果慢性期单侧MCAO患者脑梗死灶及脑梗死同侧海马较对侧相应部位FA值均降低,脑梗死灶FA值降低49.8%,脑梗死同侧海马FA值降低9.29%,ADC值均升高,脑梗死灶ADC值升高132.75%,脑梗死同侧海马ADC值升高4.9%。脑梗死灶ADC值改变率(rADC)较FA值改变率(rFA)明显,而海马rFA较rADC明显,并且脑梗死灶的rFA与认知功能存在相关性,相关系数为-0.41。结论 DTI技术可以用来定量评价慢性期脑梗死患者脑梗死灶及海马的改变,并且慢性期脑梗死患者脑梗死灶rFA与认知功能存在相关性。     

磁共振FLAIR序列和DTI在脑弥漫性轴索损伤诊断中的价值

目的 探讨磁共振FLAIR序列和DTI在急性期脑弥漫性轴索损伤(DAI)中的诊断价值及DAI病灶平均ADC值及FA值变化.方法 回顾性分析23例经临床确诊的DAI患者的影像学资料,所有患者及20例健康成人均在常规MRI扫描基础上行液体衰减翻转恢复(FLAIR)序列及弥散加权成像(DTI)扫描,比较两者DAI病灶的检出数目,分析信号特征,分区(大脑半球、胼胝体区、脑干区、小脑半球)测量DAI病灶的平均ADC值及FA值,并与正常对照组相应分区的平均ADC值及FA 值进行比较.结果 联合FLAIR序列和DTI共发现DAI病灶98个,其中DTI显示病灶而FLAIR为阴性的病灶数为11个,FLAIR显示出病灶而DTI为阴性的为5个,各区DAI病灶较之对照组,平均ADC值以降低为主,无变化及升高并存,而FA值降低.结论 对于急性期DAI病灶的显示,DTI比FLAIR序列敏感,FA值变化较平均ADC值敏感,差异有统计学意义(P<0.05).     

脑白质疏松的扩散张量成像(DTI)研究

目的 应用扩散张量成像（DTI）检查脑白质疏松（LA）病灶的平均扩散系数（DCavg）、各向异性（FA）值与LA严重程度的关系,探讨常规MBI检查正常的脑白质微结构在DTI中的变化及与认知功能的关系。资料与方法 对55例LA患者和22名健康老年人行DTI检查,测量LA病灶和正常白质区域的DCavg、FA值。结果 LA程度越严重,DCavg值越高,呈正相关;FA值越低,呈负相关。神经心理学测试（简易智能精神状态量表,MMSE）与LA患者的正常脑白质区域的DCavg、FA值明显相关,尤其是前角白质、半卵圆中心的正常脑白质。结论 DTI检查LA,其DCavg、FA值显示出特征性的改变,DTI能够发现常规MRI检查正常的脑白质微结构改变,且这种改变与认知功能相关。     

病毒性脑炎扩散张量成像的初步研究

目的:比较病毒性脑炎脑内病灶和对照侧镜像区的扩散特性的差异,探讨扩散张量成像(DTI)在诊断病毒性脑炎中的应用价值。方法:分别对13例病毒性脑炎患者行常规MRI和DTI检查,经处理后分别获得每个层面的表观扩散系数(ADC)图、各向异性(FA)图、1-VR(VR)图和纤维束成像(DTT)图,并对DTI各输出参数ADC、FA、1-VR进行统计分析。结果:13例患者共计20个病灶,病灶区的FA值及1-VR值减低,病灶区与对照侧的FA值及1-VR值间的差异有统计学意义(P<0.01),病灶区与对照侧的ADC值间的差异无统计学意义(P=0.2026,P>0.05)。FA图显示病灶的范围比常规T2WI大。DTT图显示受累白质纤维束是浸润性改变,部分纤维中断。结论:DTI指标可以反映病毒性脑炎病变组织的微观结构变化信息,为常规MRI检查提供补充信息,对其临床诊疗和评估也有一定的价值。     

MRI及DTI直方图分析对皮质下血管性认知功能障碍的评价作用

目的:利用常规MRI和扩散张量成像(DTI)直方图分析,明确血管性认知损害(VCI)患者的脑部病变严重程度评分、DTI直方图指标与简易智能量表(MMSE)间的关系.方法:对19例VCI患者、24例中风后无认知功能障碍患者(Stroke 组)行常规MRI和DTI检查,各组之间性别、年龄和受教育程度相匹配.计算T2WI可见病变体积、脑白质内高信号病灶的评分(General WMH评分),而全脑各向异性分数(FA)和平均扩散率(MD)图像分析.结果:VCI患者的FA和ADC直方图与Stroke 组不同,VCI患者平均全脑平均FA值降低,FA峰高增高.VCI组平均General WMH 评分、平均FA值、FA峰高和FA峰位置与MMSE评分相关.结论:VCI患者皮质下白质病变的严重程度与认知功能损害程度有关,全脑DTI 直方图分析较常规MRI具有更好的客观性和可重复性,某些指标可用于评价疾病的严重程度.     

多发性硬化患者脑灰质损害的MRI表现及扩散张量成像定量研究

目的 分析多发性硬化(MS)患者脑灰质病灶的MRI特征及表现正常的脑灰质(NAGM)是否存在隐匿性损伤.方法 对34例临床确诊的MS患者(MS组)和25名健康志愿者(对照组)行常规头颅MRI和扩散张量成像(DTI),观察MS的脑灰质病灶特征,测量深部灰质核团的平均扩散率(ADC)和各向异性分数(FA),采用非配对t检验比较两组间是否存在差异.结果 MR检查发现MS的脑灰质病灶共83个,占全部病灶(443个)的18.7%.分布以额叶最多,其次是颞叶与丘脑.大多数病灶呈圆形或类圆形,其中T2WI发现灰质病灶60个,液体衰减反转恢复(FLAIR)序列T2WI发现病灶78个,其中71个病灶呈高或稍高信号,3个病灶呈中心低、周围稍高的环形改变,4个呈低信号.扩散加权成像(DWI)发现高信号或低信号病灶36个,其中有9个小病灶在DWI呈明显高信号.其余病灶呈等信号而不能被发现.MS组尾状核头、壳核、丘脑的ADC值分别为(8.0±0.7)、(7.4 ±0.5)、(7.7±0.4)×10-4mm2/s,均高于对照组[分别为(7.4±0.6)、(7.0 ±0.5)、(7.2±0.7)×10-4mm2/s],差异具有统计学意义(t值分别为-3.079、-2.564、-2.722,P值均<0.05).结论 MS的脑灰质病灶在常规MRI和DWI上的表现有一定的特征,FLAIR联合DWI可提高病灶的检出,DTI可以反映出NAGM内的隐匿性损害.     

Altered diffusion tensor in multiple sclerosis normal-appearing brain tissue: cortical diffusion changes seem related to clinical deterioration

PURPOSE: To investigate normal-appearing white (NAWM) and cortical gray (NAGM) matter separately in multiple sclerosis (MS) in vivo using diffusion tensor imaging (DTI). MATERIALS AND METHODS: In 64 MS patients (12 primary progressive [PP], 38 relapsing remitting [RR], 14 secondary progressive [SP]) and 20 healthy controls, whole-brain apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps were acquired. A stimulated echo acquisition mode (STEAM) DTI sequence was used with minimal geometrical distortion in comparison to echo-planar imaging (EPI). NAWM and NAGM were identified using conventional magnetic resonance (MR) images, allowing a cautious assessment of FA in cortex. RESULTS: Histogram analyses showed significant global FA decreases and ADC increases in MS NAWM compared to control WM. MS cortical NAGM had no significant global ADC increase, but FA was decreased significantly. In regional analyses, nearly all NAWM regions-of-interest (ROIs) had significantly increased ADC compared to controls, but FA was not changed. In nearly all cortical NAGM ROIs, ADC was significantly increased and FA significantly reduced. In multiple linear regression analyses in RR/SPMS patients, NAGM-ADC histogram peak height was associated more strongly with clinical disability than T2 lesion load. CONCLUSION: Tissue damage occurs in both NAWM and cortical NAGM. The cortical damage appears to have more clinical impact than T2 lesions.     

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.     

Magnetization transfer ratio histogram analysis of normal-appearing gray matter and normal-appearing white matter in multiple sclerosis.

PURPOSE: The purpose of this work was to determine the extent of disease and disease severity in the conventional MR normal-appearing gray matter (NAGM) and white matter (NAWM) in patients with relapsing-remitting (RR) and secondary progressive (SP) multiple sclerosis (MS) utilizing quantitative magnetization transfer ratio (MTR) histogram analysis. METHOD: Twenty-seven patients with MS (16 RR, 11 SP) and 16 healthy control subjects were studied. MTR was calculated in the totally segmented GM and WM without T2 lesions in each group. RESULTS: Each of the RR and SP MS patient groups had significantly smaller MTR histogram mean values in NAGM and NAWM than the healthy subjects (p 相似文献   

Increased brain apparent diffusion coefficient in tuberous sclerosis

PURPOSE: To evaluate the water diffusivity of normal-appearing white matter (NAWM) in patients with tuberous sclerosis complex compared with that in control subjects. MATERIALS AND METHODS: Diffusion and conventional magnetic resonance (MR) imaging examinations were performed in 18 patients with clinically established tuberous sclerosis complex (10 male and eight female patients; mean age, 20.1 years; range, 12-30 years), as well as in 18 age-matched control subjects (nine male and nine female; mean age, 20.2 years; range, 11-28 years). Apparent diffusion coefficients (ADCs) were generated, and small elliptic regions of interest were manually placed both in perilesional NAWM and in six anatomic locations of NAWM remote from hamartomatous lesions. Perilesional ADCs were compared with those at the same anatomic site on the contralateral side of the brain (generalized linear regression analysis). ADCs from the predetermined sites in patients were compared with those in control subjects (generalized linear regression analysis). RESULTS: Supratentorial ADCs were higher in patients with tuberous sclerosis complex than in control subjects, and statistically significant differences were observed in the occipital white matter, frontal white matter, centrum semiovale, parietal white matter, and corona radiata (for each location, P <.001). Significant increases were also seen in the perilesional NAWM compared with NAWM at the same anatomic locations on the contralateral side (P <.001). Infratentorial ADCs were normal. CONCLUSION: Significant ADC increases were measured in the supratentorial NAWM.     

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。     

Histogram analysis of diffusion measures in clinically isolated syndromes and relapsing-remitting multiple sclerosis

Objective

The purposes of our study were to employ diffusion tensor imaging (DTI)-based histogram analysis to determine the presence of occult damage in clinically isolated syndrome (CIS), to compare its severity with relapsing-remitting multiple sclerosis (RRMS), and to determine correlations between DTI histogram measures and clinical and MRI indices in these two diseases.

Materials and methods

DTI scans were performed in 19 CIS and 19 RRMS patients and 19 matched healthy volunteers. Histogram analyses of mean diffusivity and fractional anisotropy were performed in normal-appearing brain tissue (NABT), normal-appearing white matter (NAWM) and gray matter (NAGM). Correlations were analyzed between these measures and expanded disability status scale (EDSS) scores, T₂WI lesion volumes (LV) and normalized brain tissue volumes (NBTV) in CIS and RRMS patients.

Results

Significant differences were found among CIS, RRMS and control groups in the NBTV and most of the DTI histogram measures of the NABT, NAWM and NAGM. In CIS patients, some DTI histogram measures showed significant correlations with LV and NBTV, but none of them with EDSS. In RRMS patients, however, some DTI histogram measures were significantly correlated with LV, NBTV and EDSS.

Conclusion

Occult damage occurs in both NAGM and NAWM in CIS, but the severity is milder than that in RRMS. In CIS and RRMS, the occult damage might be related to both T2 lesion load and brain tissue atrophy. Some DTI histogram measures might be useful for assessing the disease progression in RRMS patients.     

偏头痛患者磁共振弥散张量成像的初步探讨

 目的探讨偏头痛患者磁共振弥散张量中脑白质损害。方法对17例偏头痛患者和16名健康志愿者,进行磁共振弥散张量成像(diffusiontensorimaging,DTI)检查。分别测定两组受试者的双侧额叶皮层下白质、双侧侧脑室旁周围白质和双侧枕叶皮层下白质中感兴趣区(regionofinterests,ROIs)的“看似正常的白质”(normalappearingwhitematter,NAWM)表观扩散系数(apparentdiffusioncoefficient,ADC)和各向异性分数(fractionalanisotropy,FA),对两组数据进行比较分析。结果偏头痛组双侧侧脑室旁周围白质ADC值较对照组明显增高(P<0.05),双侧枕叶皮层下白质各向FA值较对照组明显降低(P<0.01)。结论DTI有助于早期发现偏头痛患者的脑白质损害。     

Magnetic resonance diffusion tensor imaging for characterizing diffuse and focal white matter abnormalities in multiple sclerosis.

High-resolution diffusion tensor imaging (DTI) was performed in 14 patients with clinically definite multiple sclerosis (MS) and the trace of the diffusion tensor () and the fractional anisotropy (FA) were determined in normal appearing white matter (NAWM) and in different types of focal MS lesions. A small but significant increase of the in NAWM compared to control white matter ((840 +/- 85) x 10(-6) mm(2)/sec vs. (812 +/- 59) x 10(-6) mm(2)/sec; P < 0.01) was found. In addition, there was a significant decrease in the FA of normal-appearing regions containing well-defined white matter tracts, such as the genu of the internal capsule. In non-acute lesions, the of T(1)-hypointense areas was significantly higher than that of T(1)-isointense lesions ((1198 +/- 248) x 10(-6) mm(2)/sec vs. (1006 +/- 142) x 10(-6) mm(2)/sec; P < 0. 001), and there was a corresponding inverse relation of FA. Diffusion characteristics of active lesions with different enhancement patterns were also significantly different. DTI with a phase navigated interleaved echo planar imaging technique may be used to detect abnormalities of isotropic and anisotropic diffusion in the NAWM and selected fiber tracts of patients with MS throughout the entire brain, and it demonstrates substantial differences between various types of focal lesions.