无痴呆的血管性认知损害全脑DTI直方图分析

目的:利用磁共振扩散张量成像(DTI)直方图分析,明确无痴呆的血管性认知损害(VCIND)患者的脑异常改变及DTI直方图指标与简易智能量表(MMSE)的相关性。方法:对13例VCIND患者和13例健康志愿者行常规MRI和DTI检查,获得全脑平均扩散率(MD)和各向异性分数(FA)图像后,分别绘制出全脑MD和FA直方图并对其进行分析。结果:与正常对照组比较,VCIND患者平均全脑FA直方图示峰位置左移,平均FA值降低(P=0.002),峰高增高(P=0.034),MD直方图明显右移、平均MD值增高(P=0.014),峰高降低(P=0.002),峰位置右移(P=0.004)。各项指标与MMSE评分均无显著相关性。结论:VCIND患者存在脑扩散异常,全脑DTI直方图分析有助于本病的诊断。     

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.     

复发好转型多发性硬化的全脑DTI直方图分析

目的 利用扩散张量成像（DTI）直方图分析，明确复发好转型多发性硬化（RRMS）患者的脑异常改变及DTI直方图指标与扩展残疾状态评分（EDSS）的相关性。资料与方法 对29例RRMS患者和35名正常志愿者行常规MRI和DTI检查，获得全脑平均扩散率（MD）和分数各向异性（FA）图像后，分别计算出全脑MD和FA直方图并对其进行分析。结果 与正常志愿者比较，RRMS患者平均全脑MD直方图右移、峰高降低；平均全脑FA直方图左移、峰高增高。RRMS患者全脑MD和FA直方图指标与正常志愿者相比，均存在显著性差异（P〈0．001）。在RRMS患者，全脑平均MD（r=0．413，P=0．026），MD直方图峰高（r=-0．424，P=0．022）和FA直方图峰位置（r=-0．594，P=0．001）与EDSS评分具有相关性。结论 RRMS患者存在明显脑扩散异常，部分DTI直方图指标可用于监测疾病进展。     

复发好转型多发性硬化表现正常脑白质DTI研究

目的:利用扩散张量成像(DTI)直方图分析,明确复发好转型多发性硬化(RRMS)患者表现正常脑白质(NAWM)的异常改变及DTI直方图指标与扩展残疾状态(EDSS)评分的相关性。方法:对29例RRMS患者和35例健康志愿者行常规MRI和DTI检查,分割提取NAWM后,绘制出NAWM的平均扩散率(MD)和部分各向异性(FA)直方图,并对其进行分析。结果:与健康志愿者比较,RRMS患者NAWM平均MD直方图右移、峰高降低;平均FA直方图左移、峰高增高。RRMS患者NAWM的平均MD、MD直方图峰位置和FA直方图峰高明显高于健康志愿者(P<0.001),而MD直方图峰高和平均FA明显低于健康志愿者(P<0.001)。在RRMS患者,所有NAWM的MD和FA直方图指标与EDSS评分均无相关性。结论:RRMS患者NAWM内存在明显扩散异常。     

脊髓型多发性硬化全脑DTI直方图分析

目的:探讨全脑DTI直方图分析对脊髓型多发性硬化(SMS)患者的诊断价值。方法:对25例SMS患者和 35例健康志愿者行常规MRI和扩散张量成像(DTI)检查,获得全脑平均扩散率(MD)和各向异性分数(FA)图像后,分别绘制出全脑MD和FA直方图并对其进行分析。结果:SMS患者全脑平均MD和FA直方图形态明显不同于健康志愿者,表现为平均MD直方图右移、峰高降低,平均FA直方图左移。SMS患者全脑平均MD(1．026×10-3mm2／s)明显高于健康志愿者(0．987×10-3mm2／s),SMS患者全脑平均FA(0．239)明显低于健康志愿者(0．246),差异均有极显著性意义(P<0．01)。结论:脑DTI检查显示SMS患者存在隐匿性脑组织损害。     

脊髓型多发性硬化脑白质DTI直方图分析

目的:研究脊髓型多发性硬化(SMS)是否存在脑白质损伤。方法:对25例SMS患者和35例正常志愿者行常规MRI和DTI检查,分割提取脑白质后,研究SMS患者脑白质平均弥散率(MD)和分数各向异性(FA)直方图的异常变化。结果:同正常志愿者比较,SMS患者脑白质的平均MD增高(P=0.005),平均FA降低(P=0.001)和MD直方图峰位置降低(P=0.007)。在SMS患者,脑白质MD直方图峰高与扩展残疾状态评分(EDSS)中度相关(r=0.453,P=0.023)。结论:SMS患者脑白质存在损伤,脑白质MD直方图峰高可用于监测SMS患者的临床进展。     

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.     

扩散张量成像对多发性硬化脑深部灰质核团纵向定量研究

目的 利用3.0T MR扩散张量成像(DTI)技术纵向定量测量复发-缓解型多发性硬化(RRMS)患者脑深部灰质核团相关参数的动态变化及其与临床相关性.方法 选取RRMS患者30例及健康对照组30名,检查前根据临床残疾状态量表(EDSS)对患者进行评分.患者行间隔平均时间约2年共2次常规MRI及DTI检查,必要时行增强扫描.选取测量大脑深部灰质核团的部分各向异性分数(FA)值及平均扩散率(MD)值,比较两次测量结果的变化并评价与临床的相关性.结果 (1)与对照组相比患者脑深部部分灰质核团FA值降低,MD值增高;(2)分析各指标与EDSS评分的相关性,结果EDSS评分与丘脑(r=0.25,P=0.04)和黑质(r=0.27,P=0.046) MD值呈正相关,与丘脑(r =0.24,P=0.03)、尾状核(r=0.414,P=0.024)FA值呈负相关性.(3)患者前后两次参数对比各核团的FA值无明显变化(P＞0.05),但尾状核(=2.36,P=0.013)、丘脑(t=3.01,P=0.009)、黑质(t=2.35,P=0.015)、红核(t=2.50,P=0.012)等核团MD值增高,以丘脑增高最明显.结论 DTI能够提示RRMS患者脑深部灰质核团受累,并且在纵向观测中可以监测患者深部灰质的病理改变.     

基于TBSS的急性CO中毒患者脑白质微细结构损伤研究

目的应用扩散张量成像(DTI)观察急性CO中毒患者脑白质结构的改变,应用影像技术量化脑白质损害程度,推测急性CO中毒迟发性脑病相关机制。方法对25例急性CO中毒患者和25例性别与年龄相匹配的健康志愿者进行头部磁共振DTI扫描,采用基于纤维束示踪的空间统计方法(TBSS),分析急性CO中毒患者脑白质平均扩散系数(MD)、各向异性分数(FA)的变化,探讨其与患者认知功能障碍间的相关性。结果与健康对照组对比,急性CO中毒患者组的放射冠、胼胝体的MD增高而FA降低(P<0.05);双侧上纵束,内、外囊,丘脑和脑干的MD增加但无FA改变(P<0.05)。与临床量表分数相关性比较发现,差异脑区FA值与MMSE评分呈一定正相关(P<0.05),差异脑区MD值与MMSE评分呈一定负相关(P<0.05)。结论DTI准确反映急性CO中毒导致脑内白质广泛的血管源性水肿以及脑白质纤维束完整性损害,可能量化反应病情缺氧脑损伤程度、预测迟发性脑病,同时DTI参数的改变还可以一定程度反映患者认知障碍情况。     

Age-related structural changes in the young adult brain shown by magnetic resonance diffusion tensor imaging

RATIONALE AND OBJECTIVE: Structure of the brain is generally thought to remain stationary over the course of young adulthood. However, there is some evidence that microstructural changes of the brain do occur during this period. Magnetic resonance diffusion tensor imaging (DTI) provides quantitative measures of structural changes in the brain. We used DTI to detect possible age-related structural changes in the brains of young adults. MATERIALS AND METHODS: Twenty-five healthy adults in their 20s and 30s were studied using DTI. Maps of mean diffusivity and fractional anisotropy (FA) were created for subsequent histogram and region-of-interest analyses, and the results were correlated with the respective ages of the subjects. RESULTS: The histogram analysis revealed a significant increase in the mean FA value (r = 0.407, P < .05) and a significant decrease in FA peak height (r = -0.578, P < .002) with increasing age. No age-related changes were observed in indices derived from mean diffusivity maps. Region-of-interest analysis showed no focal white matter regions with significant FA change. CONCLUSION: Quantitative DTI revealed age-related structural changes in the brains of young adults. Changes on FA histograms observed in this study were considered to be related to changes in the relative volumes of gray and white matter and may represent maturational changes.     

Diffusion tensor imaging in the assessment of normal-appearing brain tissue damage in relapsing neuromyelitis optica

BACKGROUND AND PURPOSE: Normal-appearing brain tissue (NABT) damage was established in multiple sclerosis by histology, MR spectroscopy, magnetization transfer imaging and diffusion tensor imaging (DTI). However, whether this phenomenon can be detected in relapsing neuromyelitis optica (RNMO) remains unclear. The aim of this study was to use DTI to investigate the presence of NABT damage in RNMO patients and its possible mechanism. METHODS: Conventional MR imaging and DTI scans were performed in 16 patients with RNMO without visible lesions on brain MR imaging and in 16 sex- and age-matched healthy control subjects. Histogram analysis of mean diffusivity (MD) and fractional anisotropy (FA) was performed in the entire brain tissue (BT), white matter (WM), and gray matter (GM). Region of interest (ROI) analysis of MD and FA was also performed in WM regions connected with the spinal white matter tracts or optic nerve (including medulla oblongata, cerebral peduncle, internal capsule, and optic radiation), in corpus callosum without direct connection with them, and in some GM regions. RESULTS: From histogram analysis, we found the RNMO group had a higher average MD of the BT, WM, and GM, a lower average MD peak height and a higher average MD peak location of the GM, and a higher average FA peak height of the WM than did the control group. From ROI analysis, compared with control subjects, RNMO patients had a higher average MD and a lower average FA in ROIs of WM connected with the spinal white matter tracts or optic nerve and a normal average MD and FA in corpus callosum without direct connection with them. In addition, a high average MD was found in parietal GM in these patients. CONCLUSIONS: Our findings confirm the presence of abnormal diffusion in brain tissue in patients with RNMO and suggest that secondary degeneration caused by lesions in the spinal cord and optic nerve might be an important mechanism for this abnormality.     

Whole-brain histogram and voxel-based analyses of diffusion tensor imaging in patients with leukoaraiosis: correlation with motor and cognitive impairment

BACKGROUND AND PURPOSE: Cerebral white matter changes, termed leukoaraiosis (LA), appearing as areas of increased signal intensity in T2-weighted MR images, are common in elderly subjects, but the possible correlation of LA with cognitive or motor deficit has not been established. We hypothesized that histogram and voxel-based analyses of whole-brain mean diffusivity (MD) and fractional anisotropy (FA) maps calculated from diffusion tensor imaging (DTI) could be more sensitive tools than visual scales to investigate the clinical correlates of LA. MATERIALS AND METHODS: Thirty-six patients of the Leukoaraiosis and Disability Study were evaluated with fluid-attenuated inversion recovery for LA extension, T1-weighted images for volume, and DTI for MD and FA. The extent of LA was rated visually. The normalized total, gray, and white matter brain volumes were computed, as well as the 25th percentile, 50th percentile, kurtosis, and skewness of the MD and FA maps of the whole brain. Finally, voxel-based analysis on the maps of gray and white matter volume, MD, and FA was performed with SPM2 software. Correlation analyses between visual or computerized data and motor or neuropsychologic scale scores were performed using the Spearman rank test and the SPM2 software. RESULTS: The visual score correlated with some MD and FA histogram metrics (P<.01). However, only the 25th and 50th percentiles, kurtosis, and skewness of the MD and FA histograms correlated with motor or neuropsychologic deficits. Voxel-based analysis revealed a correlation (P<.05 corrected for multiple comparisons) between a large cluster of increased MD in the corpus callosum and pericallosal white matter and motor deficit. CONCLUSIONS: These results are consistent with the hypothesis that histogram and voxel-based analyses of the whole-brain MD and FA maps are more sensitive tools than the visual evaluation for clinical correlation in patients with LA.     

Quantification of brain damage in cerebrotendinous xanthomatosis with magnetization transfer MR imaging

BACKGROUND AND PURPOSE: Conventional MR imaging for quantification of brain damage in monitoring the evolution of cerebrotendinous xanthomatosis (CTX) has limitations. Magnetization transfer (MT) MR imaging is overcoming these limitations. Using MT MR imaging, we sought to quantify, in vivo, the extent of brain and cerebellar damage in patients with CTX, with the ulimate goal to investigate the magnitude of the correlation between MT MR imaging findings and clinical disability. METHODS: Conventional and MT MR images of the brain were obtained in nine patients with CTX and in 10 sex- and age-matched healthy volunteers. MT ratio histograms were derived of the whole brain, brain normal-appearing white matter (NAWM), brain normal-appearing gray matter (NAGM), cerebellar NAWM, and cerebellar NAGM. Clinical disability was measured by using the Expanded Disability Status Scale (EDSS). RESULTS: Average MT ratio and peak heights of the whole brain, brain NAWM, and brain NAGM histograms in patients with CTX were significantly lower than the corresponding quantities in the control subjects. All cerebellar NAGM MT ratio histogram-derived metrics and average MT ratio of the cerebellar NAWM histogram in patients with CTX were also significantly lower than the corresponding quantities in the control subjects. Strong correlations were found between the EDSS score and a composite whole-brain MT ratio histogram score (r = 0.77, P <.01) and a composite brain white matter MT ratio histogram score (r = 0.71, P <.03). A strong correlation was also found between the cerebellar functional system score and a composite cerebellar NAWM score (r = 0.72, P <.02). CONCLUSION: The quantitative assessment of brain damage in patients with CTX with use of MT MR imaging can provide powerful measures of disease outcome.