基于纤维束空间统计分析多参数DTI在遗忘型轻度认知障碍的应用

目的:采用基于纤维束空间统计分析(TBSS)的方法分析遗忘型轻度认知障碍(aMCI)患者DTI多参数图,以研究其全脑白质纤维束损害的特点以及可能的病理机制。方法:选取29例aMCI患者和30名正常老年人(正常对照组),对全脑进行1.5T磁共振DTI序列扫描。采用FSL软件对被试的DTI扫描数据进行预处理后对aMCI组、正常对照组的部分各向异性、平均弥散、轴向弥散、径向弥散图进行基于体素的全脑非参数统计学比较。结果:与正常对照组比较,aMCI组的双侧皮质脊髓束、双侧扣带束中部、双侧胼胝体、左侧内囊前肢、左侧外囊、双侧下额枕束、左侧上纵束、左侧膝状体内视路、右侧钩束、右侧视放射出现FA值减低;胼胝体膝部及体部、左侧皮质脊髓束、左侧内囊前后肢、左侧外囊、左侧上纵束出现MD值增加;DR值增高的区域与FA值类似;DA图未发现异常;左侧白质改变多于右侧。aMCI组全脑白质各参数图与简易智能精神状态检查量表(MMSE)评分没有相关性。结论:相对于正常老年人,aMCI患者脑内多发纤维束出现损害,其DTI多参数图改变特点提示白质纤维束的损害可能主要是由退行性改变(retrogenesis)导致的。DTI各参数图的改变可能无法反映患者总体认知功能障碍的严重程度,但这还需要进一步的大样本研究。     

Principal component analysis of FDG PET in amnestic MCI

Purpose  The purpose of the study is to evaluate the combined accuracy of episodic memory performance and ¹⁸F-FDG PET in identifying patients with amnestic mild cognitive impairment (aMCI) converting to Alzheimer’s disease (AD), aMCI non-converters, and controls. Methods  Thirty-three patients with aMCI and 15 controls (CTR) were followed up for a mean of 21 months. Eleven patients developed AD (MCI/AD) and 22 remained with aMCI (MCI/MCI). ¹⁸F-FDG PET volumetric regions of interest underwent principal component analysis (PCA) that identified 12 principal components (PC), expressed by coarse component scores (CCS). Discriminant analysis was performed using the significant PCs and episodic memory scores. Results  PCA highlighted relative hypometabolism in PC5, including bilateral posterior cingulate and left temporal pole, and in PC7, including the bilateral orbitofrontal cortex, both in MCI/MCI and MCI/AD vs CTR. PC5 itself plus PC12, including the left lateral frontal cortex (LFC: BAs 44, 45, 46, 47), were significantly different between MCI/AD and MCI/MCI. By a three-group discriminant analysis, CTR were more accurately identified by PET-CCS + delayed recall score (100%), MCI/MCI by PET-CCS + either immediate or delayed recall scores (91%), while MCI/AD was identified by PET-CCS alone (82%). PET increased by 25% the correct allocations achieved by memory scores, while memory scores increased by 15% the correct allocations achieved by PET. Conclusion  Combining memory performance and ¹⁸F-FDG PET yielded a higher accuracy than each single tool in identifying CTR and MCI/MCI. The PC containing bilateral posterior cingulate and left temporal pole was the hallmark of MCI/MCI patients, while the PC including the left LFC was the hallmark of conversion to AD.     

Mapping brain morphological and functional conversion patterns in amnestic MCI: a voxel-based MRI and FDG-PET study

Purpose  

To reveal the morphological and functional substrates of memory impairment and conversion to Alzheimer disease (AD) from the stage of amnestic mild cognitive impairment (aMCI).     

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。     

DTI metrics reflecting microstructural changes of normal appearing deep grey matter in multiple sclerosis

Purpose

To evaluate the role of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in detecting microstructural changes of normal-appearing deep grey matter (NDGM) in multiple sclerosis (MS).

磁共振扩散张量成像在椎间盘损伤中的临床应用价值

目的 应用磁共振扩散张量成像(DTI)及示踪纤维(FT)技术观察椎间盘纤维环的形态和完整性,评价其在椎间盘急性损伤中的应用价值.资料与方法 分别对9名正常志愿组者、14例椎间盘外伤患者的脊椎行GE 1.5T Signa MR扫描,所有外伤患者均在伤后1周内进行.行常规MR矢状位T1,W1,T2WI及轴位T2WI,DTI扫描.将数据输人GEADW4.4工作站,应用Functool后处理软件生成各向异性分数(FA)图、平均扩散系数(ADC)图和FT图.观察纤维环的形态和完整性,测量正常纤维环和损伤断裂处及损伤周围纤维环的FA值和ADC值.结果 所有受检者均获得清晰的FA图、ADC图及椎间盘纤维环FT图.正常组纤维环在FA图和ADC图上呈一连续完整的环形结构,FA值和ADC值均匀,FT图显示纤维环形态完整.椎间盘损伤者纤维环呈不同程度的断裂,纤维板结构紊乱,髓核不同程度偏移及碎裂,断裂处纤维环的ADC值升高,FA值降低.断裂周围纤维环的ADC值降低,FA值升高.组间比较差异有统计学意义.结论 DTI-FT技术能够在活体组织中无创显示椎间盘纤维环的形态和完整性,发现急性外伤后纤维环是否损伤、断裂,断裂的位置和断裂的程度,是常规MRI检查的重要补充.     

Assessing DTI data quality using bootstrap analysis.

Diffusion tensor imaging (DTI) is an established method for characterizing and quantifying ultrastructural brain tissue properties. However, DTI-derived variables are affected by various sources of signal uncertainty. The goal of this study was to establish an objective quality measure for DTI based on the nonparametric bootstrap methodology. The confidence intervals (CIs) of white matter (WM) fractional anisotropy (FA) and Clinear were determined by bootstrap analysis and submitted to histogram analysis. The effects of artificial noising and edge-preserving smoothing, as well as enhanced and reduced motion were studied in healthy volunteers. Gender and age effects on data quality as potential confounds in group comparison studies were analyzed. Additional noising showed a detrimental effect on the mean, peak position, and height of the respective CIs at 10% of the original background noise. Inverse changes reflected data improvement induced by edge-preserving smoothing. Motion-dependent impairment was also well depicted by bootstrap-derived parameters. Moreover, there was a significant gender effect, with females displaying less dispersion (attributable to elevated SNR). In conclusion, the bootstrap procedure is a useful tool for assessing DTI data quality. It is sensitive to both noise and motion effects, and may help to exclude confounding effects in group comparisons.     

磁共振扩散张量成像在前列腺疾病诊断中的应用

目的 探讨磁共振扩散张量成像(DTI)在诊断良性前列腺增生(benign prostate hyperplasia,BPH)和前列腺癌(PCa)中的价值.资料与方法 研究对象为经病理证实的20例PCa和25例BPH患者,DTI都采用Siemens Sonata 1.5 T超导成像仪和腹部相控阵线圈,应用Siemens Leonardo工作站相应的软件进行数据处理.DTI记录感兴趣区各向异性(FA)值和平均表观扩散系数(ADC)值并绘制相应参数图和纤维示踪图像.对比不同感兴趣区的相应成像指标的差异.结果 正常外周带、BPH和PCa的FA值分别为0.16±0.03、0.23±0.04和0.46±0.02(P＜0.05).正常外周带、BPH和PCa的平均ADC值分别为(1.85±0.34)×10-3 mm2/s、(1.37±0.27)×10-3mm2/s和(0.61±0.09)×10-3 mm2/s,三者差异具有统计学意义(P＜0.05).结论 正常前列腺组织、BPH和PCa组织DTI指标存在差异,结合常规MRI检查有助于PCa的鉴别诊断.     

遗忘型轻度认知障碍患者脑血流灌注与认知功能的回归分析

目的：采用用三维动脉自旋标记（3D-ASL）技术观测轻度认知障碍（aMCI）患者的脑血流变化,探讨脑灌注变化与简易精神状态检查表（MMSE）评分间的关系,为临床早期诊断提供有效的影像学依据。方法：选择年龄、性别配对的17例 aMCI 患者和21名健康老年人,采用（3D-ASL）序列进行灌注成像。对灌注加权影像采用基于体素分析方法（VBA）进行分析,图像预处理及统计分析采用 SPM8。对 MMSE 评分与灌注参数进行回归分析。采用 AlphaSim AFNI 程序进行多重比较校正,用以控制假阳性率（P ＜0．05）。结果：与 aMCI 患者 MMSE 评分呈负相关的脑区包括：双侧尾状核,右侧壳核,右侧海马杏仁核,左侧丘脑,右侧额叶眶回,右侧中央前回;呈正相关的为左侧额中回。而正常老年对照组在左侧楔叶,颞上回、双侧颞中回表现出明显与 MMSE 评分呈正相关。结论：研究表明 aMCI 患者和健康老年人与认知功能相关的脑区血流灌注存在着明显的差异,3D-ASL 成像能够为 aMCI 患者早期诊断提供有用的影像学依据。     

BOLD-fMRl联合DTI在运动区脑肿瘤切除术中的应用

目的：探讨BOLD-fMRI联合DTI在运动区脑肿瘤术前定位运动功能区及皮质下纤维束中的可行性。方法：收集38例运动区脑肿瘤患者,随机分为试验组（术前联合应用BOLD-fMRI、DTI）20例和对照组（术前应用DTI）18例。2组均行运动区脑肿瘤神经导航术。使用SPSS 22.0软件分析2组手术效果及预后情况。结果：试验组肿瘤全切率（80.00%,16/20）高于对照组（50.00%,9/18）（P>0.05）;试验组术后致残率（30.00%,6/20）低于对照组（66.67%,12/18）（P<0.05）。结论：BOLD-fMRI联合DTI可帮助运动区脑肿瘤的术前功能区定位,以及设计手术入路,从而更好地保护患者的皮质下纤维束和运动功能区。     

DTI多参数值及DTT技术在颅内肿瘤中的应用研究

目的 探讨MR扩散张量成像(DTI)多参数值在脑肿瘤中的诊断和鉴别诊断价值;评价扩散张量纤维柬成像(DTT)在显示脑肿瘤与周围脑白质纤维束关系中的应用.资料与方法 搜集经手术病理证实的星形细胞瘤(低级别、高级别)、脑膜瘤、转移瘤患者资料(低级别星形细胞瘤15例,高级别星形细胞瘤18例,脑膜瘤16例,转移瘤10例)共59例.行常规T_1WI、T_2WI、增强T_1WI及DTI.测量病灶肿瘤实质区、瘤周水肿区、囊变坏死区、水肿邻近正常白质区及对侧正常白质区的平均扩散系数(DCavg)值、部分各向异性分数(FA)值、1-容积比(1-VR)值及相对各向异性(RA)值,分析各测量值在肿瘤的诊断及良恶性鉴别诊断中的作用.利用DTI数据进行DTT重组病变周围脑白质纤维束,观察肿瘤与脑白质纤维束的关系.结果 低级别星形细胞瘤、高级别星形细胞瘤、脑膜瘤及转移瘤的肿瘤实体、瘤周水肿区的FA值、1-VR值及RA值差异均具有统计学意义(P<0.05);对侧正常白质区DCavg值、FA值、1-VR值及RA值差异均具有统计学意义(P<0.5).FA图、FA彩色编码图、DTT图均能显示脑白质纤维受累情况,而常规MRI难以显示;脑白质纤维束与脑肿瘤的位置关系可分为四型,即推挤型、水肿型、浸润型和破坏型.低级别星形细胞瘤及脑膜瘤良性肿瘤周围的白质纤维束多呈推挤水肿改变,而高级别星形细胞瘤及转移瘤恶性肿瘤周围的白质纤维束多表现为以浸润破坏为主.结论 DTI较常规MRI能更确切、直观地显示脑内肿瘤与周围脑白质的关系,结合FA值、1-VR值及RA值能为肿瘤的诊断及鉴别诊断提供更多的依据;DTT可以为临床提供更多的肿瘤及其周围白质纤维束的信息,指导术前计划的制定和术后的评估.     

成人视放射磁共振DTI和DTT研究及初步临床应用

目的应用MR扩散张量成像（DTI）和扩散张量纤维束示踪成像（DTT）研究正常成人视放射的各向异性程度和视放射纤维束的构象特征及其临床应用价值。资料与方法对30名健康志愿者和34例枕叶病变累及视放射的患者进行MR常规及DTI序列检查,重组FA图和三维彩色编码张量图,分别测量双侧视放射区的部分各向异性（FA）值和平均扩散率（MD）值。采用扩散张量纤维束追踪软件进行视放射纤维束成像。结果彩色编码张量图均清晰显示视放射,正常视放射的FA值分别为左侧0．509±0．027、右侧0．504±0．028,MD值分别为左侧（0．756±0．049）×10^-3mm^2／s和右侧（0．734±0．045）×10^-3mm^2／s,差异均无统计学意义（P〉0．05）。DTT显示的视放射纤维束构像和走行特征符合经典神经解剖学研究。20例枕叶陈旧性梗死患者可见视放射继发Wallerian变性,FA明显降低,MD明显增高;3例脑膜瘤患者视放射完整无破坏,呈被推移改变,FA轻度降低,MD轻度增高;3例胶质瘤、1例淋巴瘤、6例转移瘤和1例结核性脑脓肿均显示视放射被破坏、中断,其各向异性消失。结论DTI、DTT可清晰显示视放射纤维束生理和病理条件下的各向异性特征,对提高视放射病变的显示和诊断具有重要意义,为了解视功能与视放射之间的关系提供了新的研究手段。     

Diagnostic utility of DTI in prostate cancer

Purpose

The aim of this study was to compare the diffusion tensor parameters of prostate cancer, prostatitis and normal prostate tissue.

Materials and Methods

A total of 25 patients with the suspicion of prostate cancer were included in the study. MRI was performed with 3 T system (Intera Achieva, Philips Medical Systems, The Netherlands). T2 TSE and DTI with ss-EPI were obtained in each subject. TRUS-guided prostate biopsy was performed after the MRI examination. Images were analyzed by two radiologists using a special software system. ROI's were drawn according to biopsy zones which are apex, midgland, base and central zone on each sides of the gland. FA and ADC values in areas of cancer, chronic prostatitis and normal prostate tissue were compared using Student's t-test.

Results

Histopathological analysis revealed carcinoma in 68, chronic prostatitis in 67 and was reported as normal in 65 zones. The mean FA of cancerous tissue was significantly higher (p < 0.01) than the FA of chronic prostatitis and normal gland. The mean ADC of cancerous tissue was found to be significantly lower (p < 0.01), compared with non-cancerous tissue.

Conclusion

Decreased ADC and increased FA are compatible with the hypercellular nature of prostate tumors. These differences may increase the accuracy of MRI in the detection of carcinoma and to differentiate between cancer and prostatitis.     

DTI在急性缺血性脑卒中所致皮质脊髓束损伤中的应用研究

目的:利用DTI探讨急性缺血性脑卒中病人大脑白质纤维束各向异性特征和皮质脊髓束受损与肌力的关系。方法:对9例正常被试和9例急性期缺血性脑卒中病人进行常规MR T1WI、T2WI和DTI检查,对数据进行离线后处理,采用dTV.II软件处理,获得FA图及方向编码彩色(DEC)图,并重建双侧皮质脊髓束3D纤维束图。结果:在正常组双侧白质纤维束FA值无明显差异,重建FA值图与方向编码彩色图可显示大部分主要的白质纤维束。在脑卒中病人组梗死区FA值显著低于健侧,两侧相比差异有显著性意义(t=4.570,P<0.001)。病变侧皮质脊髓束受压、变形、移位、部分断裂,皮质脊髓束受累情况与肌力有相关性(rs=0.888,P<0.05)。结论:DTI可显示脑内白质纤维束的走行及分布,为大脑白质纤维束的研究开辟了新的广阔领域。DTI FA值图及DEC图可以显示卒中病人梗死区白质纤维的方向与各向异性程度。3D纤维束图可以更立体直观的显示锥体束状况,有利于探讨皮质脊髓束损伤程度与肌力的关系,对临床及判断预后有重要价值。     

DTI在评价脊髓型颈椎病颈髓压迫损伤中的作用

目的:评价DTI的相对各向异性(relative FA,rFA)、相对表观扩散系数(relative ADC,rADC)对脊髓型颈椎病中颈髓压迫损伤的诊断价值。方法:收集颈髓不同压迫程度的脊髓型颈椎病98例和对照组17例健康志愿者,应用1.5T MR行常规和DTI检查,分别测量对照组(A组)C4⁵、C65、C6⁷节段和病变组(B7节段和病变组(B^D组)病变节段FA值和ADC值,并与自身同层面C2节段颈髓比较,计算出rFA值和rADC值,分析组间的差异;观察各组在颈髓纤维束图的变化。结果:AD组)病变节段FA值和ADC值,并与自身同层面C2节段颈髓比较,计算出rFA值和rADC值,分析组间的差异;观察各组在颈髓纤维束图的变化。结果:A^D组rFA值分别为0.92±0.06,0.89±0.07,0.76±0.10,0.58±0.09;rADC值分别为1.06±0.09,1.10±0.17,1.35±0.19,1.42±0.13。结论:DTI的参数变化能够量化脊髓型颈椎病颈髓受压后微细结构的变化,颈髓纤维束的图像重建能直观显示纤维束的完整性,可更加准确地评估脊髓型颈椎病的颈髓损伤。     

Evaluation of measurement uncertainties in human diffusion tensor imaging (DTI)‐derived parameters and optimization of clinical DTI protocols with a wild bootstrap analysis

Purpose

To quantify measurement uncertainties of fractional anisotropy, mean diffusivity, and principal eigenvector orientations in human diffusion tensor imaging (DTI) data acquired with common clinical protocols using a wild bootstrap analysis, and to establish optimal scan protocols for clinical DTI acquisitions.

Materials and Methods

A group of 13 healthy volunteers were scanned using three commonly used DTI protocols with similar total scan times. Two important parameters—the number of unique diffusion gradient directions (NUDG) and the ratio of the total number of diffusion‐weighted (DW) images to the total number of non‐DW images (DTIR)—were analyzed in order to investigate their combined effects on uncertainties of DTI‐derived parameters, using results from both the Monte Carlo simulation and the wild bootstrap analysis of uncertainties in human DTI data.

Results

The wild bootstrap analysis showed that uncertainties in human DTI data are significantly affected by both NUDG and DTIR in many brain regions. These results agree with previous predictions based on error‐propagations as well as results from simulations.

Conclusion

Our results demonstrate that within a clinically feasible DTI scan time of about 10 minutes, a protocol with number of diffusion gradient directions close to 30 provides nearly optimal measurement results when combined with a ratio of the total number of DW images over non‐DW images equal to six. Wild bootstrap can serve as a useful tool to quantify the measurement uncertainty from human DTI data. J. Magn. Reson. Imaging 2009;29:422–435. © 2009 Wiley‐Liss, Inc.     

扩散张量成像在神经系统疾病中的研究与应用

扩散张量成像以其特有的观察参数和指标,在神经系统生理功能和多种疾病的影像诊断和研究中得以广泛应用。本文综述了其在神经生理、脑梗死、脑肿瘤、多种脑组织变性性疾病、颞叶癫痫和血管性病变中的临床研究和实验进展情况。提出扩散张量成像的广泛应用必将引导对神经系统疾病的更准确的认识。     

额顶叶占位性病变对脑运动功能影响的DTI研究

目的:利用DTI脑白质束的FA图和白质束纤维追踪图,评估额顶叶占位病变影响下脑对指运动功能区形态及功能改变的特征.方法:病变组为20例连续搜集观察的神经外科术前检查的额顶叶占位病变患者,另选20例健康自愿者为正常对照组.采用Siemens 1.5T超导磁共振仪进行扫描,包括常规MRI和DTI.数据后处理运用美国约翰霍普金斯大学编写的DTI-Studio Version 2.02软件处理DTI数据.结果:病变组20例中最后诊断为肿瘤的15例,炎症4例,血管畸形1例.在DTI的FA图中测量两组实验对象颅内相关脑组织区域的平均FA值,显示15例肿瘤病灶区域的FA值与对照组及其自身对侧比较有降低,1例血管畸形伴化脓性感染患者FA值升高.在DTI三维白质束纤维示踪图中显示额顶叶肿瘤患者皮质脊髓束受病灶压迫而移位、中断或破坏.结论:扩散张量成像技术可以实现对活体复杂的白质纤维束结构的显示,在临床应用中DTI技术可以用于评价肿瘤与邻近白质纤维的空间解剖关系、白质纤维的受累情况,为临床病情评估和外科手术入路计划提供有效帮助,对评价术后的功能恢复潜力也有较大意义.     

Micro-structural white matter abnormalities in type 2 diabetic patients: a DTI study using TBSS analysis

Introduction

Patients with type 2 diabetes mellitus (T2DM) have usually been found cognitive impairment associated with brain white matter (WM) abnormalities. However, findings have varied across studies, and any potential relationship with Alzheimer’s disease (AD) remains unclear. The aim of this study was to assess the whole-brain WM integrity of T2DM patients and to compare our findings with those of published AD cases.

Methods

In this study, we used diffusion tensor imaging (DTI) combined with tract-based spatial statistics (TBSS) to investigate whole-brain WM abnormalities in 48 T2DM patients and 48 healthy controls. The effects of age and gender were also evaluated.

Results

In our study, significantly decreasing FA and increasing MD and DA values (P<0.05) were found in some WM regions closely related to the default mode network (DMN), including cingulum, the right frontal lobe involving the right uncinate fasciculus (UF), bilateral parietal lobes involving the superior longitudinal fasciculus (SLF) and the inferior longitudinal fasciculus (ILF), and the right middle temporal gyrus (MTG) involving the UF and the ILF. We also found abnormalities in the thalamus involving the fornix (FX), anterior thalamic radiation (ATR), and posterior thalamic radiation (PTR). The damaged regions above are similar to those found in patients with AD, as reported in previous studies.

Conclusion

The present study not only provides useful information about the WM regions and tracts affected by T2DM but also offers insight into the underlying neuropathological process in T2DM patients and the relationship between T2DM and AD.