阿尔茨海默病、额颞叶性痴呆与路易体痴呆的独特血流灌注方式

正摘要目的采用假性连续动脉自旋标记(PCASL)MRI定量测量法对兴趣区(ROI)脑血流(CBF)进行基于体素的分析,比较其在额颞叶性痴呆(FTD)、路易体痴呆(DLB)、阿尔     

磁共振ASL灌注成像及其在脑疾病诊断中的临床应用

磁共振动脉血质子自旋标记(ASL)灌注成像是将动脉血作为内源性示踪剂、无创性的观测血流灌注情况的磁共振检查技术,可以提供相应血流动力学方面的信息。笔者查阅了今年来相关文献,主要综述了ASL的基本原理、检查方法及其在脑血管疾病中的应用价值和发展趋势。     

动脉自旋标记在MR灌注成像中的研究进展

随着MR成像技术的不断改进，动脉自旋标记技术作为一种MR灌注成像新方法已得到应用。它具有无创性、可重复性高和组织对比度较好的优点，目前已初步应用于脑、肾、肺及心脏等组织器官的灌注成像研究。     

基于动脉自旋标记成像分析帕金森病神经代谢网络拓扑属性的改变

目的:应用动脉自旋标记(ASL)灌注成像(PWI)从代谢视角探讨神经网络的无创性构建,并分析其拓扑属性改变在帕金森病(PD)神经损伤中的作用机制。方法:基于磁共振ASL-PWI获取52例PD患者及相匹配的55例健康志愿者(HC组)的脑血流信息,构建组水平的神经代谢网络,采用图论分析网络的全局和节点拓扑属性(稀疏度为10%～50%,步长为1%)并进行组间比较。全局拓扑属性包括小世界属性(γ、λ、σ)、最短路径长度(Lp)、聚类系数(Cp)、全局效率(Eglob)和局部效率(Eloc),节点拓扑属性包括节点介数(BC)、节点度(DC)和节点效率(NE)。结果:两组受试者年龄、性别分布、受教育程度及认知功能(MMSE)评分的差异均无统计学意义(P>0.05)。PD组运动功能(UPDRS-Ⅲ)评分为24.60±14.00、疾病H-Y分期为1.39±0.49。在全局拓扑属性方面,PD组和HC组的神经代谢网络均显示出小世界属性(γ>1、λ≈1且σ>1);PD组的Eglob值显著高于HC组(0.25 vs. 0.23),而λ(0.42 vs. 0.46)、Lp(0.67 vs. 0...     

ASL在中枢神经系统疾病诊断中的初步应用体会

目的:探讨动脉自旋标记(ASL)MRI灌注成像技术在中枢神经系统疾病中的临床价值.方法:24例颅内病变患者,其中急性脑梗死2例,脑血管畸形7例,胶质瘤4例,淋巴瘤2例,转移瘤4例,脑膜瘤5例.所有病例均经手术病理或随访证实.用ASL技术和动态磁敏感对比成像(DSC)2种方法进行MR灌注成像,分析2种方法对颅内病变的诊断价值.结果:对急性脑梗死患者可以显示灌注缺损区或低灌注区.在评价肿瘤血供方面,ASL与DSC 2种方法所测肿瘤组织rCBF值比较,差异无显著性意义.ASL技术磁敏感伪影明显小于DSC法,对于有出血、钙化的病灶以及颅底病变的显示明显优于DSC法,提高了定量分析的准确性.结论:ASL技术在评价脑组织局部血流灌注方面,具有可重复性高、完全非侵入性、不用注射对比剂等优点.同时对于有出血、钙化或位于颅底的病变,ASL技术明显优于DSC法.     

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。     

3D ASL脑灌注成像：不同标记后延迟时间对血流测量的影响

目的:探讨3D-ASL MRI中不同标记后延迟时间对脑血流量测量值的影响.方法:选取43例健康成人志愿者(男21例,女22例;年龄25～60岁,平均41岁),采用不同标记后延迟时间(1025 ms,1525ms,2025 ms)行3D-ASL检查,测量6个部位的血流量(CBF),包括小脑皮层、丘脑核团、枕叶、颞叶、顶叶和额叶皮层.三组(不同标记后延迟时间)间各脑区CBF值的比较采用方差分析,并进行两两比较分析.结果:方差分析结果显示三组间双侧小脑半球和左侧顶叶CBF值的差异有统计学意义(右小脑半球,F值6.629,P值0.011;左小脑半球,F值6.986,P值0.007;左顶叶,F值5.143,P值0.020).进一步两两比较结果显示,双侧小脑半球、右枕叶和左顶叶的CBF值在1025 ms组与1525ms、1025ms组与2025 ms组间差异有统计学意义(P＜0.05),在1525ms组与2025ms组间差异无统计学意义比较(P＞0.05).结论:3D-ASL MRI中不同标记后延迟时间对脑血流量的测量有一定影响.     

动脉自旋标记在MR灌注成像中的研究进展

随着MR成像技术的不断改进,动脉自旋标记技术作为一种MR灌注成像新方法已得到应用.它具有无创性、可重复性高和组织对比度较好的优点,目前已初步应用于脑、肾、肺及心脏等组织器官的灌注成像研究.     

3.0TMR3D-PCASL技术在脑胶质瘤微灌注研究

目的：评价3D 伪连续动脉自旋标记技术(3D-PCASL)在脑胶质瘤术前分级价值。方法回顾性分析经组织病理学证实的20例低级别脑胶质瘤及21例高级别脑胶质瘤的3D-PCASL 图像,应用感兴趣区(ROI)分别得到肿瘤实体(TBF)、肿瘤边缘1 cm 内水肿区、肿瘤边缘1~2 cm 内水肿区以及对侧正常灰质、白质的脑血流量(CBF),对各参数值进行统计学分析。结果在高、低级别脑胶质瘤组间,除了肿瘤边缘1~2 cm 水肿区的 CBF 无统计学意义外(P >0.05),其他参数值均有统计学意义(P <0.001);在高级别胶质瘤组中,不同区域 CBF 值两两比较均有统计学意义(P <0.05),而在低级别胶质瘤组中肿瘤边缘1 cm 水肿区与肿瘤边缘1~2 cm 水肿区的 CBF 无统计学意义(P >0.05),其他区域两两相比均有统计学意义(P <0.05)。受试者工作特征曲线(ROC)曲线下面积(AUC)最大的为 TBF/对侧灰质 rCBF 值,AUC 为0.96,当阈值为2时,其敏感性和特异性也最高,分别为85.7%和100%。配对χ2检验常规序列的诊断准确率为76%,结合3D-PCASL 技术后诊断正确率为93%,2种方法比较有统计学意义(χ2=6.61,P =0.01)。结论3D-PCASL 有助于提高脑胶质瘤术前分级准确率,TBF/对侧灰质的 rCBF 值为分级最佳参数值。     

3.0T磁共振动脉自旋标记(ASL)技术诊断前列腺癌

目的:探讨前列腺磁共振动脉自旋标记(ASL)检查的影像学表现及ASL检查在前列腺癌诊断中的价值。方法:35例临床疑似前列腺肿瘤的患者行磁共振检查(包括常规T1WI和T2WI及ASL检查),回顾性分析ASL检查对前列腺肿瘤的诊断价值。以穿刺病理检查结果作为金标准将患者分为两组:前列腺肿瘤组17例,年龄16～84岁,平均63.5岁,总PSA(TPSA)0.76～1733.24ng/ml,平均207.77ng/ml;非前列腺肿瘤组18例,年龄51～80岁,平均77.3岁,总PSA 0.55～94.79ng/ml,平均13.71ng/ml。其中的12例非前列腺肿瘤和10例前列腺肿瘤患者再行磁共振灌注成像(PWI)检查。结果:ASL检查中18例非前列腺肿瘤患者前列腺外周叶和中央带平均灌注值分别为(104.19±1.65)和(137.79±1.74)ml/(100g.min);17例前列腺肿瘤患者外周叶肿瘤和中央带肿瘤的平均灌注值分别为(152.80±3.38)和(170.47±5.34)ml/(100g.min)。PWI检查中12例非前列腺肿瘤患者外围叶和中央带平均灌注值分别为(176.55±21.44)和(597.30±34.97)ml/(100g.min);10例前列腺肿瘤患者外围叶肿瘤和中央带肿瘤平均灌注值分别为(449.98±21.44)和(756.74±41.14)ml/(100g.min)。经统计学分析,前列腺非肿瘤外围叶与中央带、前列腺非肿瘤外围叶与前列腺外围叶肿瘤以及前列腺非肿瘤中央带与前列腺中央带肿瘤ASL检查平均灌注值差异均具有显著性意义(P<0.05)。结论:对于由于肾功能不良或者其它原因不能进行PWI检查而疑似前列腺肿瘤的患者可借助磁共振ASL检查明确诊断。     

动脉自旋标记灌注成像在癫痫的研究进展

癫痫是脑神经元异常放电引起反复痫性发作的脑功能失调综合征。对癫痫病人脑功能的研究成为近年来的研究热点。其中动脉自旋标记(ASL)灌注成像是一种无创定量测量脑血流灌注量的MR功能成像新技术,可以反映癫痫病人脑血流动力学的相关情况,能为更好地揭示癫痫的病理生理机制提供新的理论依据。就ASL新技术在癫痫的研究进展及临床应用进行综述。     

动脉自旋标记MRI技术在烟雾病中的应用

烟雾病（MMD）是一种发生在Willis环附近的慢性、进行性脑血管狭窄或闭塞性疾病。病人脑血管阻塞程度、侧支循环开放和脑灌注情况常影响预后和治疗决策。动脉自旋标记（ASL）MRI技术以动脉血中的水分子为内源性示踪剂进行灌注成像,可以无创性地提供脑血流动力学信息。就ASL成像原理以及常规、多期延迟、长延迟ASL,ASL-4D MR血管成像（MRA）及加速度选择性-ASL MRA等各种ASL成像技术在MMD中的临床应用进行综述。     

3D-ASL技术的研究进展及临床应用

动脉自旋标记（ASL）技术是一种内源性对比剂的功能MRI（fMRI）技术,由于利用脉冲标记的动脉血水质子作为内源性对比剂,使其具备无创、成本低、操作简单、可重复检查等优点,有效避免了外源性对比剂所带来的潜在风险。3D-ASL是基于快速自旋回波（FSE）的螺旋K（spiral K）空间采集,能有效克服平面回波成像（EPI）所带来的运动伪影和磁敏感伪影。与常规ASL相比,其主要优势包括成像范围更广,影像质量更好,采集速度更快,信号定位更精准等,故较常规ASL应用范围更广,现就3D-ASL技术的研究进展及临床应用予以综述。     

VE-ASL MRI评价脑动脉侧支循环——与DSA比较

目的:使用血管编码动脉自旋标记(VE-ASL)技术在评价颈动脉狭窄患者通过Willis环与软脑膜动脉形成的侧支循环中的价值。方法:对经超声检查诊断为单侧颈内动脉中度以上狭窄或大脑中动脉血流速度明显增加的10例患者,行VE-ASL MRI检查,测量连续7个脑部层面(层厚8mm,间隔2mm),使用红绿蓝三种伪彩色分别标记来源于右侧颈内动脉、左侧颈内动脉和后循环的血流。所有患者在MRI检查前后1周内行DSA检查。将狭窄侧大脑半球侧支循环情况分为4种类型。Ⅰ型:仅来源于对侧颈内动脉;Ⅱ型:仅来源于后循环;Ⅲ型:既来源于对侧颈内动脉,也来源于后循环;Ⅳ型:既无对侧颈内动脉供血,也无后循环的侧支供血。记录患者侧支血流中软脑膜动脉侧支的数目。计算卡帕值比较两种测量方法之间的一致性。结果:比较VE-ASL和DSA方法,DSA对侧支循环的分型结果为Ⅰ型1例,Ⅱ型2例,Ⅲ型5例,Ⅳ型2例;VE-ASL分型结果为Ⅰ型1例,Ⅱ型3例,Ⅲ型4例,Ⅳ型2例。两种检查方法的诊断一致性非常好(Kappa=0.8551,Z=4.421,P<0.0001)10例中观察到6例8处软脑膜侧支血流。结论:对颈内动脉狭窄患者,VE-ASL可以无创地评价脑动脉通过Willis环及软脑膜动脉形成的侧支循环。     

Demonstration of pulmonary perfusion heterogeneity induced by gravity and lung inflation using arterial spin labeling

Objective

To evaluate the effect of gravity and lung inflation on pulmonary perfusion heterogeneity in human lung using an arterial spin labeling (ASL) sequence called flow sensitive alternating inversion recovery (FAIR).

Materials and methods

Magnetic resonance imaging of lung perfusion using arterial spin labeling sequence was performed in supine position in ten healthy volunteers on a 1.5 T whole body scanner (GE Healthcare). Five coronal slices at an interval of 3 cm from dorsal to ventral (labeled as P3, P6, P9, P12, P15, sequently) were obtained when the volunteers performed breath holding on end expiration and the relative pulmonary blood flow (rPBF) was measured. Then, another coronal perfusion-weighted image of P3 slice was obtained on end inspiration. Tagging efficiency of pulmonary parenchyma with IR (ΔSI), rPBF and area of the P3 slice were analyzed.

Results

(1) Along the direction of gravity, a gradient was visually perceived as a vertical increase in rPBF. There were significant statistic differences in rPBF between any two coronal planes except that between P12 and P15. In supine position, regression coefficients of right and left lung were −4.98 and −5.16, respectively. This means that rPBF decreased 4.98 (right) and 5.16 (left) for each centimeter above the dorsal. No statistical difference was seen between ROIs placed along iso-gravitational plane. (2) For a same slice, there were significant statistic differences in ΔSI, rPBF and area at different respiratory phases (P < 0.05). Greater ΔSI and more perfusion were observed on end expiration than on end inspiration. The area was larger on end inspiration than on end expiration.

Conclusion

Both gravity and respiratory phase are important determinants of pulmonary perfusion heterogeneity. FAIR is sensitive to demonstrate gravity- and respiratory phase-dependent differences in lung perfusion. Positioning the patient so that the area of interest is down-gravity and asking patient to hold breath on end expiration may help in detection of perfusion defects.     

多相位ASL在颅脑疾病中的初步应用

目的评估多相位ASL在颅脑疾病中的临床应用价值。方法 20例颅内病变患者,其中脑膜瘤8例,胶质瘤2例,胶质母细胞瘤1例,淋巴瘤1例,脑梗死6例,神经源性肿瘤1例,室管膜瘤1例。对患者行3.0MR常规T1WI、T2WI、FLAIR和病变部位8相位ASL扫描。计算第1、5、8相位病变部位相对脑血流量值(rCBF),对病变的灌注情况进行分析。结果出血性脑梗死病例早、中、晚期均表现为高灌注。常规扫描双侧枕叶未发现明显异常病例,ASL显示右侧枕叶出现低灌注。急性或亚急性梗死患者和脑软化患者三期均表现为低灌注。其余脑梗死患者不同时相高、低灌注情况均出现。脑肿瘤病例中,部分肿瘤早、中、晚期灌注状态一致,如胶质瘤和部分脑膜瘤病例。部分肿瘤不同时相显示不同的灌注状态。结论本研究表明评估脑内病变的灌注情况具有时间依赖性。多相位ASL对于早期诊断脑缺血性疾病,评估脑梗死后的再灌注有独特的优势。     

Model-free arterial spin labeling quantification approach for perfusion MRI.

In this work a model-free arterial spin labeling (ASL) quantification approach for measuring cerebral blood flow (CBF) and arterial blood volume (aBV) is proposed. The method is based on the acquisition of a train of multiple images following the labeling scheme. Perfusion is obtained using deconvolution in a manner similar to that of dynamic susceptibility contrast (DSC) MRI. Local arterial input functions (AIFs) can be estimated by subtracting two perfusion-weighted images acquired with and without crusher gradients, respectively. Furthermore, by knowing the duration of the bolus of tagged arterial blood, one can estimate the aBV on a voxel-by-voxel basis. The maximum of the residue function obtained from the deconvolution of the tissue curve by the AIF is a measure of CBF after scaling by the locally estimated aBV. This method provides averaged gray matter (GM) perfusion values of 38 +/- 2 ml/min/100 g and aBV of 0.93% +/- 0.06%. The average CBF value is 10% smaller than that obtained on the same data set using the standard general kinetic model (42 +/- 2 ml/min/100 g). Monte Carlo simulations were performed to compare this new methodology with parametric fitting by the conventional model.     

Posterior hypoperfusion in Parkinson's disease with and without dementia measured with arterial spin labeling MRI

Purpose:

To determine whether quantitative arterial spin labeling (ASL) can be used to evaluate regional cerebral blood flow in Parkinson's disease with dementia (PDD) and without dementia (PD).

Materials and Methods:

Thirty‐five PD patients, 11 PDD patients, and 35 normal controls were scanned by using a quantitative ASL method with a 3 Tesla MRI unit. Regional cerebral blood flow was compared in the posterior cortex using region‐of‐interest analysis.

Results:

PD and PDD patients showed lower regional cerebral blood flow in the posterior cortex than normal controls (P = 0.002 and P = 0.001, respectively, analysis of variance with a Bonferroni post hoc test).

Conclusion:

This is the first study to detect hypoperfusion in the posterior cortex in PD and PDD patients using ASL perfusion MRI. Because ASL perfusion MRI is completely noninvasive and can, therefore, safely be used for repeated assessments, this method can be used to monitor treatment effects or disease progression in PD. J. Magn. Reson. Imaging 2011;33:803–807. © 2011 Wiley‐Liss, Inc.     

Mapping of vertebral artery perfusion territories using arterial spin labeling MRI

PURPOSE: To demonstrate the use of a noninvasive arterial spin labeling (ASL) MRI technique and evaluate vertebral artery (VA) territories in the brain. MATERIALS AND METHODS: Vessel-encoded ASL was used to determine the territories of the left and right VAs in five healthy subjects. Territory maps were analyzed quantitatively by comparing the fractional contributions of the left and right VAs in selected regions of interest within the brain. RESULTS: VA territory maps demonstrated a complicated pattern of perfusion to the posterior aspect of the brain, but were consistent with the posterior cerebral and cerebellar artery distributions. Cerebellar perfusion was predominantly ipsilateral (P<0.01). The total left and right VA contributions were unequal (P<0.01), and there was relatively little mixing in the vertebrobasilar system. CONCLUSION: Vessel-encoded ASL can reveal individual VA territories in the brain. In a small sample of healthy volunteers the VAs appeared to contribute unequally, provide predominantly ipsilateral supply to the cerebellum, and undergo minimal mixing in the basilar artery.