MR脑血流灌注成像在星形细胞肿瘤中的应用研究

目的　评价MR脑血流灌注成像在星形细胞肿瘤中的应用价值。方法　经手术及病理证实的星形细胞肿瘤共 2 6例。行常规MR及MR灌注成像检查。构建局部脑血容量 (rCBV)图 ,并计算肿瘤最大相对局部脑血容量 (rrCBV)值。评价星形细胞肿瘤的rCBV图表现 ,并分析平均最大rrCBV值与肿瘤病理学级别之间的关系。结果　 9例Ⅱ级星形细胞瘤的rCBV分布较均匀 ,接近或略高于对侧脑白质。 7例Ⅲ级和 10例Ⅳ级星形细胞肿瘤的rCBV分布明显不均匀 ,肿瘤实性区rCBV多有不同程度的升高 ;瘤内囊变坏死区和瘤周水肿区rCBV降低。增强MRI上 ,2例Ⅲ级和 2例Ⅳ级肿瘤内无明显强化区域 ,在rCBV图上脑血容量明显升高。Ⅱ～Ⅳ级肿瘤最大rrCBV的平均值分别为 0 91±0 18、3 5 1± 1 0 1和 4 75± 1 2 3;Ⅱ级与Ⅲ级 (t=6 79,P <0 0 1)、Ⅱ级与Ⅳ级 (t=9 75 ,P <0 0 1)、Ⅲ级与Ⅳ级之间 (t=2 19,P <0 0 5 )平均最大rrCBV值差异均有显著性意义。结论　MR脑血流灌注成像可观察星形细胞肿瘤的血流灌注变化 ,对判断星形细胞肿瘤的病理学分级有重要临床意义。     

基于组织相似度图谱的MR灌注成像评价脑胶质瘤的价值探讨

目的 探讨基于组织相似度图谱(TSM)MR灌注成像(PWI)评价脑胶质瘤血流灌注情况的可行性及在胶质瘤分级中的价值.方法 搜集经手术病理证实的24例脑肿瘤(Ⅱ级9例,Ⅲ级8例,Ⅳ级7例)患者的MR常规及灌注成像资料.经TSM算法软件和MRI工作站PWI后处理软件将扫描数据进行处理,得到TSM图和脑血容量(CBV)图.分别测算肿瘤实质区和正常脑白质区(WM)的CBVPWI值或CBVTSM值,然后计算出脑胶质瘤的rCBVPWI值、rCBVTSM值,并分别对Ⅱ级、Ⅲ级、Ⅳ级胶质瘤rCBVPWI值和rCBVTSM值进行统计学分析.结果 (1)Ⅱ级、Ⅲ级和Ⅳ级胶质瘤的rCBVPWI值和rCBVTSM值之间差异均无统计学意义.(2)Ⅱ级胶质瘤的rCBVPWI值(1.83 ±0.48)显著低于Ⅲ级(5.95±2.52) (P =0.002)和Ⅳ级(6.47±2.30)(P=0.001).Ⅲ级和Ⅳ级之间差异无统计学意义(P=0.631).同样,Ⅱ级胶质瘤的CBVTSM值(2.18 ±0.38)显著低于Ⅲ级(6.06 ±2.81) (P =0.007)和Ⅳ级(6.27±2.76) (P =0.006).Ⅲ级和Ⅳ级之间差异无统计学意义(P=0.87).结论 基于TSM的MR灌注成像可用于评价脑胶质瘤的血流动力学变化,并能于术前对胶质瘤进行分级诊断.     

脑胶质瘤磁共振灌注成像与病理对照研究

目的　评价磁共振灌注成像在术前评估脑胶质瘤组织病理学分级中的价值。方法　经手术及病理证实的胶质瘤共 2 6例。行常规MR及MR灌注成像检查。构建脑血流容积 (CBV)图和脑血流量 (CBF)图 ,计算最大相对CBV(rCBV)和最大相对CBF(rCBF) ,并与组织病理学分级对照。结果　低级组 (Ⅰ～Ⅱ级 )胶质瘤rCBV、rCBF范围分别为 0 .72～ 4.2 6和 0 .82～ 2 .89,均值分别为 2 .10± 1.18和 1.5 2± 0 .65。高级组 (Ⅲ～Ⅳ级 )胶质瘤rCBV、rCBF范围分别为 0 .89～ 10 .0 2和 1.5 0～ 6.40 ,均值分别为 5 .2 3± 1.86和 4.81± 2 .60。 2组rCBV和rCBF差别有显著性 (t检验 ,Ρ <0 .0 1)。非参数相关性分析表明rCBV与rCBF间有显著的正相关性 (r =0 .712 ,Ρ <0 .0 1)。结论　脑磁共振灌注成像对胶质瘤的术前分级有重要临床意义。     

脑胶质瘤灌注成像与病理对照研究

目的运用磁共振灌注成像(PWI)获取对比剂首过期间的兴趣区图像,评价rCBV和rCBF在术前评估脑胶质瘤组织学分级中的价值.材料和方法本组共30例颅脑胶质瘤,均经病理证实.常规MRI扫描后行PWI,PWI序列为GRE-EPIRIT2*WI,由灌注资料获取rCBV、rCBF图像,计算最大rCBV和rCBF并与组织病理学分级对照.结果Ⅲ～Ⅳ级胶质瘤(18例)的rCBF、rCBV分别为1.8～7.4和2.67～10.48,均值分别为5.4±1.8和5.75±3.85.I～Ⅱ级胶质瘤(12例)rCBF、rCBV分别为0.5～1.7和1.36～3.16,均值分别为1.4±0.3和1.75±0.65.两组间rCBF和rCBV差别有显著性(P＜0.01,studentt检验).结论灌注成像对颅脑胶质瘤的术前分级有重要价值.     

MR灌注成像在评价神经胶质瘤肿瘤血管中的价值

目的　运用磁共振灌注成像 (PWI) ,探讨肿瘤血流容积在术前评估胶质瘤组织学分级中的价值。并与微血管密度 (MVD)对照 ,评估二者的相关性。方法　共搜集了 3 2例神经胶质瘤 ,均系常规MR扫描后 ,在首过期间行PWI ,通过非弥散示踪模式 ,获得局部相对脑血流容积 (rCBV)彩图 ,并计算肿瘤局部血容量。用免疫组织化学检测技术测量MVD ,以判断血管形成活性。将rCBV、rCBV比值与术后病理分级 ,以及rCBV与MVD进行统计学分析。结果　分级高的胶质瘤 ( 18例 )rCBV比值在 5 3 0～ 14 80之间 ,均值为 8 3 2± 1 68。分级低的胶质瘤 ( 14例 )rCBV比值在 0 89～ 5 40之间 ,均值为 2 93± 1 19。经组间t检验 ,两组rCBV比值均数差异有非常显著性意义 (t=9 618,P =0 0 0 0 )。分级高的胶质瘤rCBV值在 43 55～ 2 90 54之间 ,中位数为 113 60。分级低的肿瘤rCBV值在 9 66～168 76之间 ,中位数 2 8 84。经组间Wilcoxon检验 ,两组rCBV值差异有非常显著性意义 ( |Z| =4 0 2 7,P =0 0 0 0 )。rCBV和MVD的关系用线性回归分析 ,二者密切相关 (r =0 87,P <0 0 0 1)。结论　胶质瘤MR灌注成像与病理分级和MVD有良好的相关性 ,和常规MR联合应用 ,可显著提高胶质瘤术前分级的准确性 ,有效指导治疗方案的选择 ,有助于判断预后     

MR灌注成像在脑胶质瘤术前分级中的价值

目的 :运用磁共振灌注成像 (PWI)技术 ,探讨脑血流容量 (rCBV)及其rCBV比值在脑胶质瘤术前分级中的价值。方法 :3 2例经病理证实的脑胶质瘤 ,其中Ⅰ级 2例 ,Ⅱ级 9例 ,Ⅲ级 14例 ,Ⅳ级 7例 ,行PI扫描 ,计算肿瘤最大rCBV及其rCBV比值 ,将结果与病理分级进行对照。结果 :低分级胶质瘤rCBV值为 43 .82± 15 .5 1,rCBV比值为 2 .89± 0 .83 ;高分级胶质瘤rCBV值为 12 4.3 2± 3 0 .5 4,rCBV比值为 7.82± 1.2 1;两组的rCBV值以及rCBV比值差异均有显著性意义 (P <0 .0 0 1)。结论 :不同分级的胶质瘤之间的rCBV及rCBV比值差异存在显著性意义 ,PWI技术有助于脑胶质瘤的术前分级。     

胶质瘤MR灌注成像与分子病理学的对照研究

目的探讨胶质瘤最大相对脑血容量(rCBV)与肿瘤微血管密度(MVD)以及血管内皮生长因子(VEGF)表达水平之间的相关性。资料与方法对30例脑胶质瘤(低级别8例,高级别22例)术前行MR常规及灌注成像检查。MR灌注指标rCBV值由肿瘤及对侧正常脑白质的CBV相比后得出。对肿瘤病理片进行SP法免疫组织化学染色,并检测MVD及VEGF表达水平,然后分别对低级别、Ⅲ级和Ⅳ级胶质瘤的rCBV值和MVD及VEGF表达水平进行分析。结果经Spearman相关分析,rCBV值与MVD之间呈显著正相关(r=0·447,P<0.05)。按VEGF低表达和高表达分为两组,两组的rCBV值分别为4.39±3.41(1.20~13.35)、8.24±3.23(3.25~14.26),MVD分别为70.11±32.37(34.5~140.0)、167.15±100.66(38.2~360.0)。两组间的rCBV值或MVD均有显著性差异(P<0·01)。结论rCBV值与MVD及VEGF表达水平之间存在良好的相关性,可用于术前评价肿瘤的血管新生。随着该技术的不断提高,MR灌注成像对于评价胶质瘤的术前病理分级以及指导肿瘤的基因治疗和估计预后具有较好的应用前景。     

MR扩散、灌注成像在脑胶质瘤分级中的价值

目的评价MR扩散、灌注成像在脑胶质瘤病理分级诊断中的价值.资料与方法对经组织病理学证实的28例脑胶质瘤患者(19例高级别胶质瘤,9例低级别胶质瘤),术前行常规MR平扫,MR扩散成像、灌注成像和常规增强扫描,重建出表观扩散系数(ADC)彩图和相对脑血流容量(rCBV)彩图后,分别测量出肿瘤实质部分的最小ADC值和最大rCBV值.用两样本t检验分析肿瘤的ADC值、rCBV值与术后病理学分级间的关系,用线性回归分析ADC值与rCBV值间的关系.结果 19例高级别胶质瘤的平均最小ADC值为(0.95±0.29)×10-3 mm2/s;9例低级别胶质瘤的平均最小ADC值为(1.37±0.16)×10-3 mm2/s,两组间ADC值有统计学显著性差异(t=4.09,P<0.001).高级别胶质瘤的平均最大rCBV值为5.49±1.87;低级别胶质瘤的平均最大rCBV值为1.70±0.73,两组间rCBV值有统计学显著性差异(t=5.89,P<0.001).此外,ADC值与rCBV值间有统计学显著负线性相关性(r＝-0.51,P<0.05).结论 MR扩散、灌注成像能提供常规MRI所不能获取的诊断信息,更低的ADC值和更高的rCBV值提示为高级别胶质瘤;更高的ADC值和更低的rCBV值提示为低级别胶质瘤,它们对脑胶质瘤的术前分级诊断具有重要价值.     

MR灌注成像在鉴别单发脑转移瘤与高级别胶质瘤中的价值

目的探讨MR灌注成像在鉴别单发脑转移瘤与高级别胶质瘤中的作用及价值。方法对10例单发脑转移瘤和15例高级别胶质瘤患者行手术前MR灌注成像扫描。分析其MR灌注曲线及伪彩图像,测量肿瘤实质部分及瘤周水肿区最大相对脑血容积(rCBV)值及相应部位相对平均通过时间(rMTT)数值并将所测值进行t检验。结果单发脑转移瘤的MR灌注曲线形态和伪彩图像中的色彩特点与高级别胶质瘤有明显区别。单发脑转移瘤与高级别胶质瘤肿瘤实质部分的最大rCBV值分别为3.70±2.34、6.01±2.17,瘤周水肿区则分别为0.80±0.28、1.77±1.19。单发脑转移瘤与高级别胶质瘤肿瘤实质相应部位的rMTT值分别为1.17±0.39、1.11±0.18,瘤周水肿区则分别为1.17±0.38、1.02±0.20。两者肿瘤实质部分和瘤周水肿区的rCBV值均数之间差异有统计学意义(P<0.05),而相应的rMTT值均数之间差异没有统计学意义(P>0.05)。结论MR灌注成像对术前鉴别单发脑转移瘤与高级别胶质瘤有临床实用价值。     

应用磁共振灌注加权成像评估星形细胞肿瘤病理分级的研究

目的探讨MR灌注加权成像(PWI)评估星形细胞肿瘤病理分级的价值。资料与方法 110例经手术病理证实的星形细胞肿瘤于术前进行常规MRI平扫、增强和PWI。其中,低级别(Ⅰ～Ⅱ级)肿瘤40例,高级别(Ⅲ～Ⅳ级)肿瘤70例(Ⅲ级33例,Ⅳ级37例)。PWI采用梯度回复回波-回波平面成像(GRE-EPI)技术。盲法检测并计算肿瘤和瘤周区最高相对脑血容量(rCBV)值。比较和分析不同病理级别肿瘤间及瘤周区之间最高rCBV值的差异。两组间比较用t检验;多组间比较用方差分析,两两比较用LSD检验;检验水准α=0.05。应用受试者工作特征(ROC)曲线评估最高rCBV值的诊断效能。结果Ⅰ～Ⅱ级和Ⅲ～Ⅳ级肿瘤最高rCBV值分别为1.708±0.535,5.521±1.626;Ⅲ级和Ⅳ级分别为4.207±0.808和6.693±1.220;Ⅰ～Ⅱ级与Ⅲ～Ⅳ级间、Ⅰ～Ⅱ级与Ⅲ级和Ⅳ级间、Ⅲ级与Ⅳ级间肿瘤最高rCBV值差异均有统计学意义(均为P=0.000)。Ⅰ～Ⅱ级和Ⅲ～Ⅳ级瘤周区最高rCBV值分别为0.898±0.233和1.730±0.507,Ⅲ级和Ⅳ级分别为1.446±0.246和1.983±0.547;Ⅰ～Ⅱ级与Ⅲ～Ⅳ级...     

MR physics of body MR imaging

This article reviews the major challenges of body imaging, describes the problems that arise from motion, and the many attempts at reducing this problem. Fast imaging sequences and approaches to reducing the data acquired without sacrificing image quality are described.     

MR并行采集技术及其在心脏MR检查中的应用

一、概述 传统的MRI主要依靠在K空间中梯度场来进行相位方向编码,为了提高MR成像速度,需要相应增加梯度场的强度和切换率,甚至采用双梯度技术,梯度场强高达80 mT/m,切换率200 T·m-1·s-1,并应用了快速成像序列,如回波平面成像(EPI)、快速小角度激发成像(FLASH)等,但仍不能满足运动器官如心脏快速成像的需要.     

In-office MR imaging

The development of new metal alloys, along with more innovative magnet technology, has permitted the construction of smaller magnets for magnetic resonance (MR) systems, which, in turn, has allowed development of MR imaging systems designed to be physically smaller than conventional whole-body MR imaging systems. These specialized devices are commonly referred to as "niche," "dedicated," or "extremity" MR imaging systems. Performing MR imaging procedures with this type of system offers distinct advantages that include reduced overall costs, more convenient installation and siting, and greater patient comfort and safety. Importantly, these critical features permit extremity MR imaging systems to be readily utilized in an "in-office" setting. This article will provide an overview of the technical aspects and clinical applications for extremity MR imaging systems, present patient management issues, and discuss the economic and practical considerations of the use of extremity MR imaging systems in an in-office environment.     

Ultra-high-speed MR imaging

Conventional magnetic resonance imaging (MRI) has been shown to provide excellent morphological images of the body organs, particularly structures undergoing little physiologic motion. Nevertheless, the clinical usefulness of MRI has been hampered by long acquisition times, high cost of scanning because of limited patient throughput, and image artifacts due to patient motion. With recent technical developments, several ultrafast scanning techniques capable of acquiring images in a breath-hold now find their introduction into clinical use. The system improvements are potentially useful for a vast range of applications hitherto not accessible to MR imaging. Among these are functional brain imaging, realtime imaging of cardiac motion and perfusion, fast abdominal imaging, improved MR angiography, and potentially real-time monitoring of interventional procedures. Whereas some ultrafast techniques can be performed on conventional scanners, echo-planar imaging, the fastest currently available data acquisition strategy, requires specially designed hardware. This article provides on overview of the technical advances in the ultrafast MRI and discusses potential applications and the possible future impact on body scanning.Correspondence to: G. K. von Schulthess     

Parallel MR imaging

Parallel imaging is a robust method for accelerating the acquisition of magnetic resonance imaging (MRI) data, and has made possible many new applications of MR imaging. Parallel imaging works by acquiring a reduced amount of k-space data with an array of receiver coils. These undersampled data can be acquired more quickly, but the undersampling leads to aliased images. One of several parallel imaging algorithms can then be used to reconstruct artifact-free images from either the aliased images (SENSE-type reconstruction) or from the undersampled data (GRAPPA-type reconstruction). The advantages of parallel imaging in a clinical setting include faster image acquisition, which can be used, for instance, to shorten breath-hold times resulting in fewer motion-corrupted examinations. In this article the basic concepts behind parallel imaging are introduced. The relationship between undersampling and aliasing is discussed and two commonly used parallel imaging methods, SENSE and GRAPPA, are explained in detail. Examples of artifacts arising from parallel imaging are shown and ways to detect and mitigate these artifacts are described. Finally, several current applications of parallel imaging are presented and recent advancements and promising research in parallel imaging are briefly reviewed.     

Stereoscopic MR imaging

The visual fusion of two projection or slice-selective magnetic resonance (MR) images taken at two oblique angles imparts three-dimensional (3D) information within the projection or slice. This approach to 3D MR is rapid and straightforward, requiring only two oblique images and, at most, only a simple optical stereoscope for viewing. Stereoscopic images of the vascular system of a rat were obtained using the intravascular contrast agent albumin-(Gd-diethylenetriaminepentaacetic acid). Stereoscopic images of the human head showing CSF distribution were acquired using a long echo time sequence. These images illustrate the potential clinical applications of this technique.     

Breast MR imaging

Contrast-enhanced breast MR imaging has made significant progress since its introduction into the radiological literature in 1989. The techniques and technology continue to be refined, and understanding of the interpretation strategies has improved dramatically. Clinical applications in difficult diagnostic cases and the evaluation of the extent of breast cancer are now being practiced in many centers worldwide. There is great excitement over the potential for breast MR imaging to address the problem of screening high-risk women. Despite all of the progress made over the past years, however, there is still a significant amount of work ahead before a clear understanding of how this technique will affect the health care of women is obtained.     

MR imaging of adrenoleukodystrophy

Summary We performed MRI in 7 cases with adrenoleukodystrophy (ALD), including 3 cases with childhood ALD, 3 cases with adrenomyeloneuropathy (AMN) and one symptomatic heterozygote. The symptomatic heterozygote was the mother of the patient with AMN. High-field-strength (2.0T) MRI was used in two cases with childhood ALD. In all 3 cases of childhood ALD, MR showed widespread lesions in both cerebral hemispheres. Areas of low intensity in the diencephalon or striatum on heavily T2-weighted images at 2.0T were seen in 2 cases with childhood ALD. Cerebral lesions confined to the internal capsule, cerebral peduncle and optic radiation in the adult onset ALD including AMN and symptomatic heterozygote, have not been reported and this confinement may indicate an early stage of the disease.