动态磁敏感对比增强与动脉自旋标记灌注技术在脑梗死中的研究

目的 对比研究动脉自旋标记法(ASL)和动态磁敏感对比增强(DSC)MR脑灌注成像的优缺点及其在脑梗死患者中的临床应用价值.资料与方法 对22例脑梗死患者行ASL[流动敏感交变反转恢复技术(FAIR)]与DSC MR灌注扫描,以扩散加权成像(DWI)拟合灌注成像图,分别取梗死灶中央、边缘、周围作为感兴趣区(ROI),以对侧大脑半球镜像部位为参照,分别测量相对脑血流量(rCBF)值,根据rCBF值将病侧血流灌注状况分为灌注不足与灌注增加,做统计学分析.结果 (1)22例66个ROI中,61个ROI在两种灌注检查中表现一致,5个ROI在两种灌注检查中表现不同,经一致性检验,Kappa值=0.76.(2)两种灌注检查表现一致的61个ROI中,有43个ROI呈灌注不足,其中29个ROI的rCBF值FAIR灌注法低于DSC灌注法,经配对资料的t检验,差异有统计学意义(P＜0.05).另18个ROI呈灌注增加,其中9个ROI的rCBF值FAIR灌注法高于DSC灌注法,经配对资料的t检验,差异无统计学意义(P＞0.05).结论 ASL(FAIR)灌注法与DSC灌注法对判断脑梗死患者的血流灌注状态具有很好的一致性,ASL(FAIR)灌注法对检测脑梗死患者的低灌注更敏感,且无需注射对比剂,有望作为脑梗死患者血流灌注状态的筛查方式,有阳性发现时,再做DSC灌注以提供更详细的灌注信息.     

3D动脉自旋标记灌注成像联合3D磁敏感加权血管成像在急性脑梗死诊治中的应用价值

目的回顾性分析急性脑梗死磁共振3D动脉自旋标记灌注成像(3D ASL)与3D磁敏感加权血管成像(SWAN)的影像表现,并进一步评价其对溶栓治疗的指导价值。方法采用3.0T MRI扫描仪,63例急性脑梗死患者行常规MRI序列、DWI、MRA、3D ASL及SWAN检查。两名神经影像诊断专家分别独自评价DWI、MRA、3D ASL、SWAN影像表现。结果 52例(82.5%)患者ASL-CBF表现为血流灌注减低,其中38例(73.1%)患者ASL低灌注范围明显大于DWI;16例(30.8%)ASL低灌注患者SWAN像检测到大脑中动脉血栓。11例(17.5%)患者ASL显示明显高灌注。12例(75.0%)ASL低灌注患者和4例(25.0%)ASL高灌注患者,SWAN像显示梗死区内和/或边缘存在出血性低信号。结论3D ASL联合SWAN成像既能评价急性脑梗死患者的脑血流灌注特点、责任动脉内血栓,还能够评价患者潜在出血风险,对急性脑梗死患者溶栓治疗具有重要的指导价值。     

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。     

动脉血质子自旋标记与动态磁敏感对比MRI在急性脑缺血患者中的应用价值

目的对比研究动脉血质子自旋标记（ASL）与动态磁敏感对比（DSC）MRI在急性脑缺血诊断中的应用价值。方法27例发病3d内的急性脑卒中患者，均采用3．0TMR行脉冲式ASL和DSCMR检查。观察2种技术的灌注表现，包括灌注不足、正常灌注、延迟灌注、过度灌注等，采用Mann—Whitney检验做定性分析。在扩散加权成像显示的病变部位及对侧正常半球的镜像区域分别确定3个感兴趣区（ROI），测量信号强度并计算信号强度比（病侧／对照侧），并将结果做配对t检验。结果定性分析显示27例患者中，2l例2种技术检查结果一致（灌注不足14例，正常灌注5例，过度灌注2例）。6例2种技术不一致，其中4例ASL显示灌注不足而DSC显示延迟灌注，2例ASL显示正常灌注而DSC显示延迟灌注，两者间差异无统计学意义（P〉0．05）。定量分析示，2种技术的病侧与对照侧信号强度比值ASL为0．7l±0．46，DSC为0．73±0．42，两者间差异无统计学意义（P〉0．05）。结论无创性ASL技术在检测灌注异常时与DSCMRI有相似的敏感性；ASL可与常规MR检查相结合，为临床诊断急性缺血性卒中提供有价值的信息。     

2种MRI灌注成像在脑梗死溶栓治疗中的应用

目的 对比研究动脉血质子自旋标记(arterial spin labeling,ASL)与动态磁敏感对比成像(dynamic susceptibility contrast,DSC)在大脑中动脉供血区脑卒中溶栓治疗中的应用价值.方法 67例发病12 h内的急性脑卒中患者,除常规MRI检查外,在DWI确认为大脑中动脉缺血区脑梗死者,采用GE 1.5T MR进行脉冲式ASL和DSC 检查,并分别用2种灌注技术与DWI结合来判断缺血半暗带,2种方法 判断结果 采用Kappa一致性检验.结果 定性分析显示67例患者中61例2种技术检验结果 一致,6例2种技术检验结果 不一致,Kappa >0.75(K=0.820 9),两者一致性较好.定量分析示,2种技术的病侧与对照侧信号强度比值ASL为0.70±0.44,DSC为0.71±0.41,两者间差异无统计学意义(P>0.05).结论 无创性ASL技术检测灌注异常时与DSC 技术有相似的敏感性;ASL可作为一项DSC的替代技术用于指导大脑中动脉供血区脑卒中溶栓治疗.     

动脉自旋标记技术在颅内肿瘤中的临床应用进展

灌注是指血流通过毛细血管网,将携带的氧和营养物质输送给组织细胞的一种基本生物功能。磁共振灌注成像凭借其对微血管灌注的敏感性,已经广泛应用于临床各方面,包括对肿瘤的鉴别,脑梗死区域的界定,以及其他疾病的诊断。磁共振灌注成像可分为2大类,即对比剂首过磁共振灌注成像法和动脉自旋标记(arterial spin labeling,ASL)法。前者需要静脉注射顺磁性对比剂,如 Gd-DTPA 或 SPIO,然后进行快速 MR 扫描,在其分类中,动态磁敏感对比成像(dynamic susceptibility contrast,DSC)不仅拥有较高的空间分辨率,还能同时测量大脑血流量(cerebral blood flow, CBF)和脑血容积(cerebral blood volume,CBV),因而在临床上广泛应用。然而,ASL 却无须注射外源对比剂就能够测量脑血流量,是近年发展起来的一种 MRI灌注新技术。由于 ASL 技术具有安全无创、成本低廉、简单方便、可重复性好等优点,并且可对肿瘤的血管生成进行准确评估,已逐渐成为颅内肿瘤病变诊断、治疗及预后评估研究的新热点。本文就 ASL 技术的工作原理、分类及其在颅内肿瘤的应用做一综述。     

3．0TMR动脉自旋标记与动态磁敏感对比增强灌注技术在脑胶质瘤术前分级中的对照研究

目的：对照研究动脉自旋标记（arterial spin labeling,ASL）与动态磁敏感对比增强（dynamic susceptibility contrast—enhanced．DSC）灌注成像技术在脑胶质瘤中的灌注特点．探讨ASL在脑胶质瘤术前分级中的临床应用价值。方法：使用3．0TMR成像系统对23例脑胶质瘤患者（术后病理证实高级别胶质瘤17例,低级别胶质瘤6例）术前行常规扫描外,加扫ASL及DSC灌注检查。测量肿瘤实质部分最大肿瘤血流量（maximal tumor blood flow,TBFmax）以及对侧白质、对侧灰质、对侧半球的血流量（cerebral blood flow,CBF）。结果：23例脑胶质瘤患者。两种灌注方法均获得了一致的灌注结果,TBF max／对侧白质CBF、TBFmax／对侧灰质CBF及TBFmax／对侧半球CBF的各比值在ASL和DSC两种技术之间的差异无明显统计学意义（P〉0．05）,但在高、低级别胶质瘤之间的差异均有统计学意义（P〈0．05）。在ASL法中,TBFmax／对侧白质CBF、TBFmax／对侧灰质CBF及TBFmax／对侧半球CBF分别取阈值为3．06、0．46和1．31时,其敏感性分别为i00％、88．2％和100％．特异性分别为83．3％、83．3％和100％。结论：ASL在评估脑胶质瘤血流灌注方面与DSC之间有相似的敏感性,具有可重复性高、完全无创性等优点,同时有助于术前对脑胶质瘤进行分级评判。     

动脉自旋标记技术在颅脑疾病中的初步研究

目的 评价动脉自旋标记(ASL)技术在颅脑疾病中的临床应用价值.方法 26例颅脑病变患者,其中急性脑梗死7例,短暂性脑缺血发作2例,神经元移行异常(多小脑回畸形)2例,胶质瘤9例,脑膜瘤4例,原始神经外胚层肿瘤1例,脑脓肿1例.除使用3.0T MR成像系统对所有患者行常规扫描及ASL序列(Q2TIPS)外,肿瘤及脑脓肿患者加做增强扫描,余患者(包括脑脓肿)加扫FLAIR、DWI序列(其中1例TIA患者行MRA检查),观察所得相对局部脑血流量(rCBF)图,分析双侧灌注变化.结果 ASL-rCBF图像上,缺血性脑血管病及神经元移行异常显示相应血供异常区域明显低灌注,脓肿及肿瘤显示与其血供基本相符的灌注情况.结论 ASL技术能快速非侵袭性地提供脑血流灌注信息,可用于缺血性脑血管病的早期诊断、神经元移行异常、肿瘤与脓肿病灶血供的初步评估及胶质瘤的分级.     

动脉自旋标记和动态磁敏感对比增强灌注成像在脑膜瘤中的对比应用

目的 分析比较动脉自旋标记(arterial spin labeling,ASL)和动态磁敏感对比增强(dynamic susceptibility con-trast-enhanced,DSC)灌注成像技术在脑膜瘤中的临床应用价值.方法 前瞻性分析41例在我院行磁共振检查的脑膜瘤患者的影像资料,除颅脑MRI常规序列外...     

全脑3D-ASL和SWI联合检查在急性大面积脑梗死治疗中的价值

目的探讨3D-ASL和SWI技术对急性大面积脑梗死治疗方案的指导价值。方法回顾性分析46例急性大面积脑梗死患者在治疗前后的ASL和SWI表现,其中4例于治疗前、4例于动脉溶栓治疗后、5例静脉溶栓治疗后、33例抗凝治疗后、12例于治疗后30~60天复查,根据治疗方案的不同,分别统计急性大面积脑梗死患者ASL像高/低灌注、SWI像出血或侧枝循环形成的影像学表现,按NIHSS评分评价临床愈后效果。结果本组46例中,14例患者ASL像上呈局部或大部分高灌注,占30%,其余32例为低灌注,占70%;4例行动脉溶栓,ASL像上呈局部或大部分高灌注,SWI像上均可见面积大小不等的低信号出血灶;5例行静脉溶栓,ASL像上呈高灌注3例、呈低灌注2例,SWI像可见脑出血1例;33例行抗凝治疗,7例于治疗后ASL像上呈高灌注,其中5例SWI像可见低信号出血灶,2例SWI像上未见出血灶;26例ASL像呈低灌注,10例SWI像上可见出血灶,16例SWI像未见出血灶。4例有房颤病史且平常口服抗凝药物的患者在抗凝治疗后均于ASL像上表现为高灌注。本组16例中,24例于SWI像上显示梗死区或周围血管增多、增粗,占52%。SWI像上9例可见沿大脑中动脉走行的条状低信号影,占20%。NIHSS评分:1例死亡,5例无变化,其余40例经治疗后均有不同程度好转。结论联合运用3D-ASL和SWI技术指导急性大面积脑梗死患者的治疗,具有重要的临床价值。     

Monitoring Cerebral Perfusion Changes Using Arterial Spin-Labeling Perfusion MRI after Indirect Revascularization in Children with Moyamoya Disease

ObjectiveTo assess the role of arterial spin-labeling (ASL) perfusion MRI in identifying cerebral perfusion changes after indirect revascularization in children with moyamoya disease.Materials and MethodsWe included pre- and postoperative perfusion MRI data of 30 children with moyamoya disease (13 boys and 17 girls; mean age ± standard deviation, 6.3 ± 3.0 years) who underwent indirect revascularization between June 2016 and August 2017. Relative cerebral blood flow (rCBF) and qualitative perfusion scores for arterial transit time (ATT) effects were evaluated in the middle cerebral artery (MCA) territory on ASL perfusion MRI. The rCBF and relative time-to-peak (rTTP) values were also measured using dynamic susceptibility contrast (DSC) perfusion MRI. Each perfusion change on ASL and DSC perfusion MRI was analyzed using the paired t test. We analyzed the correlation between perfusion changes on ASL and DSC images using Spearman''s correlation coefficient.ResultsThe ASL rCBF values improved at both the ganglionic and supraganglionic levels of the MCA territory after surgery (p = 0.040 and p = 0.003, respectively). The ATT perfusion scores also improved at both levels (p < 0.001 and p < 0.001, respectively). The rCBF and rTTP values on DSC MRI showed significant improvement at both levels of the MCA territory of the operated side (all p < 0.05). There was no significant correlation between the improvements in rCBF values on the two perfusion images (r = 0.195, p = 0.303); however, there was a correlation between the change in perfusion scores on ASL and rTTP on DSC MRI (r = 0.701, p < 0.001).ConclusionRecognizing the effects of ATT on ASL perfusion MRI may help monitor cerebral perfusion changes and complement quantitative rCBF assessment using ASL perfusion MRI in patients with moyamoya disease after indirect revascularization.     

FAIR and dynamic susceptibility contrast-enhanced perfusion imaging in healthy subjects and stroke patients

PURPOSE: To compare dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI) and the flow-sensitive alternating inversion recovery (FAIR) technique for measuring brain perfusion. MATERIALS AND METHODS: We investigated 12 patients with acute stroke, and 10 healthy volunteers with FAIR and DSC maps of regional cerebral blood volume (rCBV), mean transit time (MTT), and regional cerebral blood flow (rCBF). RESULTS: In volunteers good gray/white-matter contrast was observed in FAIR, rCBF, and rCBV maps. Regions with high signal intensities in FAIR matched well with high values of rCBV and rCBF. In ischemic stroke patients a high correlation (r = 0.78) of the ipsi- to contralateral signal intensity ratios in FAIR and rCBF was observed in areas with perfusion abnormalities. In contrast, FAIR and rCBV (r = 0.50), and FAIR and MTT (r = -0.22) correlated only modestly. Furthermore, FAIR and rCBF demonstrated similar sizes of perfusion abnormality. CONCLUSION: This study demonstrates for the first time that FAIR and rCBF depict similar relations of perfusion in ischemic stroke patients and healthy subjects.     

Arterial spin labelling MRI for assessment of cerebral perfusion in children with moyamoya disease: comparison with dynamic susceptibility contrast MRI

Introduction

This study seeks to evaluate the diagnostic accuracy of cerebral perfusion imaging with arterial spin labelling (ASL) MR imaging in children with moyamoya disease compared to dynamic susceptibility contrast (DSC) imaging.

Methods

Ten children (7 females; age, 9.2?±?5.4 years) with moyamoya disease underwent cerebral perfusion imaging with ASL and DSC on a 3-T MRI scanner in the same session. Cerebral perfusion images were acquired with ASL (pulsed continuous 3D ASL sequence, 32 axial slices, TR?=?5.5 s, TE?=?25 ms, FOV?=?24 cm, matrix?=?128?×?128) and DSC (gradient echo EPI sequence, 35 volumes of 28 axial slices, TR?=?2,000 ms, TE?=?36 ms, FOV?=?24 cm, matrix?=?96?×?96, 0.2 ml/kg Gd-DOTA). Cerebral blood flow maps were generated. ASL and DSC images were qualitatively assessed regarding perfusion of left and right ACA, MCA, and PCA territories by two independent readers using a 3-point-Likert scale and quantitative relative cerebral blood flow (rCBF) was calculated. Correlation between ASL and DSC for qualitative and quantitative assessment and the accuracy of ASL for the detection of reduced perfusion per territory with DSC serving as the standard of reference were calculated.

Results

With a good interreader agreement (κ?=?0.62) qualitative perfusion assessment with ASL and DSC showed a strong and significant correlation (ρ?=?0.77; p?<?0.001), as did quantitative rCBF (r?=?0.79; p?<?0.001). ASL showed a sensitivity, specificity and accuracy of 94 %, 93 %, and 93 % for the detection of reduced perfusion per territory.

Conclusion

In children with moyamoya disease, unenhanced ASL enables the detection of reduced perfusion per vascular territory with a good accuracy compared to contrast-enhanced DSC.     

Ultra-fast three-dimensional MR perfusion imaging of the entire brain in acute stroke assessment

We sought to evaluate a three-dimensional (3D) whole-brain perfusion technique based on echo-shifting (PRESTO) for its performance in evaluation of acute stroke. Twenty-six patients were scanned within 6 hours after onset of hemispheric symptoms, and the results were compared with results of diffusion-weighted imaging (DWI) and digital subtraction angiography (DSA). The signal-to-noise ratio of the images was 61 +/- 3 pre-contrast and 47 +/- 3 at the bolus peak. Brain coverage on perfusion parameter maps was 95% +/- 2% compared with that displayed on T2-weighted images, with only minor artifacts related to susceptibility at the skull base. Measured regional cerebral blood volume (rCBV) reduction closely correlated to lesion size on initial DWI and to final clinical outcome (P = 0.006), consistent with results previously reported for 2D perfusion methods. Mismatches between DWI and perfusion imaging characterized the total extent of tissue at risk, and the contrast timing correlated with the amount of collateral circulation as shown on DSA. In conclusion, 3D imaging using the PRESTO technique permits high-quality perfusion imaging of the entire brain.     

Noninvasive measurement of relative cerebral blood flow with the blood bolus MRI arterial spin labeling: basic physics and clinical applications

Knowledge of tumor blood flow is important for diagnosis and follow-up of brain tumors after therapy, especially to discriminate necrosis from tumor recurrence after radiation or chemotherapy. Meanwhile, perfusion and diffusion MRI, besides MR-angiography, are state of the art in stroke imaging. Until now, perfusion imaging was mostly performed using the first-pass dynamic susceptibility-weighted contrast-enhanced (DSC) MRI. The MRI-based arterial spin labeling technique (ASL) is a novel approach for measuring relative cerebral blood flow (rCBF) without using extrinsic contrast agents, by labeling spins of flowing arterial blood as intrinsic contrast agent. This article describes physical basics of ASL and shows clinical examples in neuroimaging such as in meningeoma, glioblastoma, oligodendroglioma, and cerebral ischemia, using the Q2TIPS ASL technique. Gray matter is clearly visible, while the observed white matter signal obtained by Q2TIPS is only slightly higher than background noise. Venous blood causes artefacts in the sagittal sinus and other large superficial veins in the subarachnoid space. Meningeoma and glioblastoma show elevated rCBF, whereas oligodendroglioma and cerebral ischemia have reduced rCBF values. Arterial-spin-labeling techniques are noninvasive tools for measuring rCBF within 5 min, using a standard MRI scanner.     

Combined arterial spin label and dynamic susceptibility contrast measurement of cerebral blood flow

Dynamic susceptibility contrast (DSC) and arterial spin labeling (ASL) are both used to measure cerebral blood flow (CBF), but neither technique is ideal. Absolute DSC‐CBF quantitation is challenging due to many uncertainties, including partial‐ volume errors and nonlinear contrast relaxivity. ASL can measure quantitative CBF in regions with rapidly arriving flow, but CBF is underestimated in regions with delayed arrival. To address both problems, we have derived a patient‐specific correction factor, the ratio of ASL‐ and DSC‐CBF, calculated only in short‐arrival‐time regions (as determined by the DSC‐based normalized bolus arrival time [Tmax]). We have compared the combined CBF method to gold‐standard xenon CT in 20 patients with cerebrovascular disease, using a range of Tmax threshold levels. Combined ASL and DSC CBF demonstrated quantitative accuracy as good as the ASL technique but with improved correlation in voxels with long Tmax. The ratio of MRI‐based CBF to xenon CT CBF (coefficient of variation) was 90 ± 30% (33%) for combined ASL and DSC CBF, 43 ± 21% (47%) for DSC, and 91 ± 31% (34%) for ASL (Tmax threshold 3 sec). These findings suggest that combining ASL and DSC perfusion measurements improves quantitative CBF measurements in patients with cerebrovascular disease. Magn Reson Med 63:1548–1556, 2010. © 2010 Wiley‐Liss, Inc.     

颅内和头颈部病变CT血管造影的三维成像

探讨螺旋ＣＴ血管造影及三维图像重建（３Ｄ－ＳＣＴＡ）在颅内和头颈部病变诊断中的价值。材料和方法：９８例头颈部病变患者接受了３Ｄ－ＳＣＴＡ检查,其中包括颅内动脉瘤３２例,颅内ＡＶＭ５例,颈动脉粥样梗化３５例,脑膜瘤１１例,硬膜型海绵状血管瘤２例,颅底神经纤维瘤３例,颈部肿块６例,颈椎椎管内神经纤维瘤４例。结果：全部患者顺利经受螺旋ＣＴ血管造影检查,３５例颈动脉粥样硬化均显示清楚,且能够检出附壁钙化性     

Brain perfusion territory imaging: methods and clinical applications of selective arterial spin-labeling MR imaging

The ability to visualize perfusion territories in the brain is important for many clinical applications. The aim of this overview is to highlight the possibilities of selective arterial spin-labeling (ASL) magnetic resonance (MR) imaging techniques in the assessment of the perfusion territories of the cerebral arteries. In the past decade, the optimization of selective ASL MR techniques to image the cerebral perfusion territories has resulted in numerous labeling approaches and an increasing number of clinical applications. In this article, the methods and clinical applications of selective ASL MR imaging are described and the importance of perfusion territory information in studying cerebral hemodynamic changes in patients with cerebrovascular disease is shown. In specific patient groups with cerebrovascular disease, such as acute stroke, large artery steno-occlusive disease, and arteriovenous malformation, selective ASL MR imaging provides valuable hemodynamic information when added to current MR protocols. As a noninvasive tool for perfusion territory measurements, selective ASL may contribute to a better understanding of the relation between the vasculature, perfusion, and brain function.     

前颅凹底脑膜瘤的影像诊断与病理对照研究

目的:探讨前颅凹底脑膜瘤的影像学和病理组织学之间的关系.材料和方法:病理证实的前颅凹底脑膜瘤27例,男8例,女19例.年龄13～79岁,平均62岁.均行MRI检查(增强16例);15例行CT检查(增强8例).分析CT、MRI影像,并与手术病理对照.结果:27例前颅凹底脑膜瘤,起源于嗅沟15例,前颅凹底6例,眶顶4例,鞍结节向前生长2例.多数水肿明显,均匀增强;少数不均匀增强,并出现脑膜尾征,少数伴钙化、坏死、囊变和出血.累及邻近颅骨时引起骨质增生.结论:前颅凹底脑膜瘤具有典型的影像学表现.CT和MRI具有诊断价值,MRI优于CT ,但CT观察钙化和骨质改变优于MRI.