动态磁敏感性对比灌注MRI鉴别脑脓肿和高恶度脑肿瘤

脑脓肿和某些原发脑肿瘤在M RI上均可表现为环状强化,病变内壁光滑,病变周围小卫星灶。T2W I上脓肿壁呈低信号和DW I上脓液呈高信号等有助于两者的鉴别,但特异性差。该文探讨动态磁敏感对比灌注M RI对于脑脓肿和高恶度脑肿瘤的鉴别诊断价值。脑脓肿4例(3例经病理证实,1例经临床证实),高恶度脑肿瘤4例,均经病理证实(多形性胶质母细胞瘤2例,胶质肉瘤1例,间变性星形细胞瘤1例)。使用1.5T M R设备横断面T1W I和T2W I横断面和冠状T1W I增强扫描,并行各向同性SE-EPIDW I(b=1000m m2/s)及SE-EPI动态磁敏感对比灌注扫描(团注对比剂,0…     

鼻咽癌MRI动态增强特征观察研究

目的:通过MRI动态增强扫描,定量测量鼻咽癌MRI动态参数,观察鼻咽癌强化方式及时间 - 信号曲线的变化,探讨肿瘤的动态增强特征.方法:本组28例先行MR动态增强扫描,后经鼻咽纤维镜活检证实为鼻咽癌.所有病例在MRI动态扫描前均未行放疗、化疗等抗肿瘤治疗.MRI应用3D FAST TOP SPGR 序列行动态增强扫描,获取T1WI 动态增强系列图像.工作站对同一位置的系列图像逐一像素计算最大上升斜率,并以伪彩图像显示该值.观察肿瘤MRI 动态增强信号变化特征及时间 - 信号曲线走势.结果:鼻咽癌T1WI动态增强信号变化特征为早期、快速、明显增强,其后病灶强化程度有所下降.根据强化形态特征将其强化类型分为三种:线样强化型(1例),边缘强化型(1例),团块样强化型(26例).根据曲线走势可将时间 - 信号曲线分为Ⅰ、Ⅱ、Ⅲ三型.同一肿瘤,不同ROI的曲线类型可不同,通常强化明显区域其曲线类型为Ⅰ型或Ⅱ型,相反为Ⅲ型.结论:应用动态MRI增强扫描,获取MRI动态参数和反映信号强度变化的时间 - 信号曲线,为无创显示鼻咽癌肿瘤微循环特点、肿瘤血液灌注等功能性特征提供了新的手段.     

3D ASL灌注成像与MRI对比增强扫描对脑肿瘤的术前诊断价值

目的 :通过对脑肿瘤的三维动脉自旋标记成像(3D ASL)与MRI增强扫描的图像分析,探讨3D ASL对脑肿瘤的术前诊断价值。方法:选取经手术病理证实的脑肿瘤患者53例,包括低级别胶质瘤15例,高级别胶质瘤17例,脑膜瘤12例,转移瘤9例。均行3D ASL、MRI平扫及增强扫描,比较相对脑血流图(r CBF)的差异及增强扫描对比剂显影的差异性。结果:MRI增强扫描联合应用3D ASL对脑肿瘤的诊断符合率为96.2%(51/53),与MRI增强扫描比较差异无统计学意义(χ2=1.361,P 0.05)。胶质瘤、脑膜瘤、转移瘤比较,低级别胶质瘤组肿瘤实性区域各灌注指标均低于其他各组(均P0.05),余各组间比较,差异无统计学意义(P 0.05)。9例脑转移瘤肿瘤强化区外周均无ASL高灌注信号。结论:3D ASL能定量反映肿瘤微循环的灌注情况,与MRI常规序列联合应用,对颅脑肿瘤的术前评估具有重要的临床价值,可作为MRI常规序列的重要补充。     

高压注射器在磁共振灌注及血管成像中的应用

目的：通过压力注射器在磁共振灌注及血管成像中的应用体会,探讨其在磁共振检查中的临床意义,方法：30例脑肿瘤患者脑灌注成像,28例血管病变患者常规增强扫描及5例冠心病患者心肌灌注成像,使用Medrad Spectris MR injector注射器经上肢大静脉进行快速大剂量对比剂团注。造影前根据病变或血管的大小,首先预设置流速,流量及注射时间,对选定某一病变区域用动脉程序行短时扫描或延迟扫描,作为对照,另12例脑肿瘤患者脑灌注成像采用手推方式注射,并对脑灌注曲线做对比分析,结果：42例脑肿瘤中30例经手术病理确诊,6例外院手术,6例本院活检穿刺,28例血管病变经IADSA证实,所有检查均获成功。脑血流灌注曲线压力注射器组优于手推组,28例血管病变血管造影像及5例心肌灌注图像均达诊断标准。结论：压力注射器可保持稳定速度,确保对比剂浓度以完成准确灌注,江可根据灌注成像及血管造影成像程序调节速度和时间,更为精确地进行上述检查。     

动脉自旋标记技术在脑肿瘤术前评估中的应用研究

目的对比研究动态磁敏感对比增强(dynamic susceptibility contrast-enhanced,DSC)MRI及动脉自旋标记(aterial spin labeling,ASL)技术在脑肿瘤术前评估中的作用,探讨ASL技术在脑肿瘤术前评估中的应用价值。方法经病理证实的41例脑肿瘤患者,其中高级别胶质瘤8例,低级别胶质瘤16例,转移瘤7例,脑膜瘤10例。采用3.0 T MR扫描仪行ASL流动敏感交互反转恢复(flow-sensitive alternating inversion recovery,FAIR)法及DSC灌注检查,将原始图像分析处理后分别获取肿瘤实性区域、瘤周1 cm及2 cm区域血流灌注指标平均最大相对脑血流量(rCBFmax)比值。所得数据经统计学处理,P<0.05为差异有统计学意义;对两种技术所得平均rCBFmax比值行线性回归分析,得出其相关系数,了解其相关性。结果在肿瘤实性区域,两种技术所得rCBFmax低级别胶质瘤组与其他各组间差异均有统计学意义(P<0.05);在瘤旁1 cm区域,DSC技术所得rCBFmax高级别胶质瘤组与其他各组间差异均有统计学意义(P<0.05),而ASL技术rCBFmax在各组差异无统计学意义(P>0.05)。两种技术所得rCBFmax在各组脑肿瘤瘤区实性区域与瘤旁1 cm及2 cm区域差异均有统计学意义(P<0.05)。两种技术于肿瘤实性区域所得灌注指标显著正相关(r=0.907)。结论 ASL技术是一种无需注射对比剂的MR灌注方法,可考虑作为常规检查方法评估脑肿瘤血流动力学情况,指导脑肿瘤术前级别评估。     

脉络膜裂囊肿的影像学诊断

本文分析CT、MR诊断的21例脉络膜裂囊肿,以提高对本病的认识。1材料与方法1.1一般资料MR诊断为脉络膜裂囊肿21例,男15例,女6例,年龄5~60岁,平均35.2岁。其中外伤5例,健康查体5例。1.2扫描方法采用日立MRP-7000AD 0.3T磁共振机,行自旋回波序列(SE)T1WI(TR/TE=500ms/20ms),快速自旋回波序列(FSE)T2WI(TR/TE=4000ms/117ms)及FLAIR序列(TR/TE/TI=6000ms/117ms/1500ms)分别采集轴位图像及冠状位SE-T1WI、矢状位FSE-T2WI图像,层厚5~8mm,间隔1~2mm。3例患者按照0.1mmol/kg静脉注射欧乃影后行轴位、冠状位及矢状位T1WI增强扫…     

胶质瘤动态增强磁化率MR灌注成像研究

目的研究胶质瘤动态增强磁化率MR灌注图像、曲线特点及各指标相应数值对胶质瘤术前分级的作用和价值.材料和方法对31例经常规MRI检查证实颅内占位并诊断为胶质瘤的病人进行动态增强磁化率MR灌注检查.使用GE 1.5T Horizon Signa MR扫描仪,行常规增强前后及GE-PET序列扫描;原始图像经在线工作站处理后产生灌注曲线及各功能图像,与常规MR图像进行比较.测量肿瘤不同部位各MR灌注指标相应数值并将所测量数值输入个人电脑,使用SPSS软件进行统计处理.结果我们将每例病人对侧正常脑白质的各种灌注指标设置为1,低级别肿瘤中心实质部分、边缘实质部分和瘤周水肿区的rCBV值分别为1.82±1.11,2.67±1.10,0.80±0.37;rCBF值分别为1.73±1.21,3.01±1.60,0.74±0.33;MTT值分别为0.92±0.38,1.03±0.17,1.03±0.27;TTP值分别为0.93±0.42,1.02±0.18,1.02±0.31.高级别肿瘤各相应部位rCBV值分别为2.29±1.31,3.99±0.68,1.23±0.56;rCBF值分别为2.27±1.43,5.41±3.05,1.25±0.81MTT值分别为0.91±0.35,1.07±0.16,1.04±0.20;TTP值分别为0.82±0.38,1.03±0.24,0.93±0.25.不同级别胶质瘤各功能图像及灌注曲线具有不同特点,与病理结果相符.低级别胶质瘤与高级别胶质瘤周边血容积、血流量及瘤周水肿区血容积的相应数值有统计学意义差异(P＜0.05).结论胶质瘤动态增强磁化率MR灌注图像、曲线及灌注各指标相应数值,可以提供常规MR图像所无法获得的肿瘤血供信息;结合常规MR图像,MR灌注对胶质瘤术前分级和治疗方案的制定有临床实用价值.     

增强MR肺灌注扫描诊断肺动脉栓塞的初步研究

目的应用增强MR肺灌注扫描技术（MRPP）与增强MR肺动脉造影（MRPA）、核素肺灌注扫描相对照，初步探讨此项成像技术诊断肺动脉栓塞的敏感性及特异性。方法14例最终明确诊断为肺动脉栓塞患者，均行增强MRPA及MRPP。5例患者同时拥有核素肺通气一灌注扫描结果。3例经溶栓治疗后复查MRPA及MRPP。通过在上、中下肺野和异常区域内设置感兴趣区（ROI），测量信号强度（SI）、时间一信号曲线，获取灌注高峰期信号强度变化率。结果14例肺动脉栓塞患者，MRPA发现共62支肺动脉闭塞，MRPP共发现55个肺灌注异常区与之相吻合。符合率为88．71％，14例中MRPP显示有25个肺段合并有段及段以远的肺动脉栓塞。5例同时拥有核素扫描结果的患者，核素显示37个段灌注缺损，MRPP显示33个段，敏感度为89．19％，3例经溶栓治疗后复查MRPA和MRPP，均见受累肺动脉明显改善，肺灌注缺损区明显减少。正常灌注与灌注缺损区及低灌注区的信号强度变化率（TROS）差异有统计学意义（t=22．882，P〈0．01）。结论MRPP能够显示肺动脉栓塞的灌注缺损区和低灌注区。时间一信号曲线显示肺动脉栓塞区对比剂无灌注高峰期，信号曲线波动幅度小，信号强度变化率减低。MRPP对段及段以远的肺动脉栓塞的显示有较高的研究价值。MRPP联合MRPA可进一步提高MR诊断肺动脉栓塞的敏感度。     

多层CT灌注成像技术在脑肿瘤诊断中的应用

目的：探讨多层螺旋CT灌注扫描成像技术在脑肿瘤诊断中的应用价值。方法：收集2004．11—2006．1月辽宁医学院附属第一医院脑肿瘤住院患者43例，对所有患者行普通CT扫描、增强CT扫描及CT灌注成像。首先对患者行普通CT扫描及增强CT扫描，以平扫最大肿瘤层面为中心行灌注检查，应用“Toggling—table”技术行CT灌注扫描取得数据用Per-fusion3软件中的Brain tumor灌注分析软件进行分析。结果：本研究中普通CT、增强CT及CT灌注成像均能清晰地显示病变，但CT灌注成像能够获得更多的病变信息资料，获得的脑肿瘤区域的CBF、CBV、PS灌注图，PS图像可以清晰显示肿瘤区与水肿区及肿瘤的血管通透性。结论：多层CT灌注成像可以快速、简捷、清晰的显示出脑肿瘤的大小与轮廓，且灌注成像对在体观察脑肿瘤血流状态及肿瘤血管功能提供了一种新的方法。     

兔肝MR灌注表现的实验研究

目的 探讨兔正常肝脏的MR灌注特征.方法 新西兰大白兔10只,体重2.5～3.0 kg,分别进行MR灌注成像.采用TFE序列.灌注成像参数:矩阵89×256,TR 4.3 ms,TE 1.4 ms,激励次数1,视野355 mm×75 mm,层厚5 mm,间距1 mm,NSA为1次.扫描层面数4层,每层反复激励65次,总扫描时间为1 min 20 s.将原始图像输入到PHILIPS后处理工作站(VIEWFORUM),自动生成MR灌注图.分析MR灌注图像及不同组织MR灌注成像特点.结果 肝血容量(HBV)图、肝血流量(HBF)图清楚勾画出肝脏轮廓.腹主动脉强化曲线,表现为速升速降,MR信号强度峰值496±131,肝静脉表现为逐渐升高,MR信号强度峰值323±92,强化时间比腹主动脉晚.正常肝组织强化曲线,呈缓慢升降,MR信号强度峰值194±58.腹主动脉、肝静脉及正常肝组织MR信号强度峰值的比较有统计学差异(F=10.27,P=0.012).结论采用TFE序列可成功进行兔MR灌注成像,HBV图、HBF图清楚勾画出肝脏轮廓,强化曲线可初步反映兔肝脏不同组织的血流情况.     

动态增强磁共振门静脉成像及临床应用

目的　探讨动态增强磁共振门静脉成像 (DCE -MRP)技术要点及临床应用优势。方法　 3 1例进行腹部常规扫描时疑有门静脉异常的患者接受了动态增强磁共振门静脉成像扫描 ,其中正常 8例 ,异常 2 3例。使用高压注射器将Gd -DTPA造影剂经手背静脉注入血管 ,应用透视触发造影技术确定扫描延迟时间 ,所有图像分别进行数字减影、最大信号强度投影 (MIP)重建。结果　3 1例患者均获得了清晰、立体的门静脉图像。 8例无肝脏疾患者 ,DCE -MRP均能完整显示门静脉主干及肝内 5级以上的分支。 2 3例异常 ,其中肝硬化门静脉高压 13例 ,均显示门静脉扩张迂曲 ,2例显示门静脉主干闭塞 ;肝癌 9例 ,其中门静脉主干和 (或 )其主分支闭塞 3例 ;肝右叶巨大血管瘤 1例。结论　动态增强磁共振门静脉成像为新的磁共振血管成像技术 ,成像效果与传统的血管造影相仿 ,具有明显的临床应用优势     

Dynamic susceptibility contrast-enhanced echo-planar imaging of cerebral gliomas. Effect of contrast medium extravasation

PURPOSE: To assess the influence of the degree of contrast medium extravasation on different DSC EPI MR sequences for perfusion MR imaging. MATERIAL AND METHODS: 60 patients with cerebral gliomas were examined by either an FID EPI or an SE EPI DSC MR sequence. The acquired images were evaluated on a qualitative and quantitative basis. For qualitative assessment, the homogeneity of the signal time curve, image artifacts, the degree of signal drop and the degree of enhancement were evaluated. The quantitative assessment included the percentage of signal drop and the contrast-to-noise ratio of the different EPI sequences was analyzed. RESULTS: FID EPI presented a more homogeneous signal time curve and a more pronounced susceptibility effect than the SE EPI sequence. Due to the lesser susceptibility effect, the SE EPI sequence was not as sensitive to contrast media extravasation. The signal returned to baseline in all patients. In patients with strongly enhancing lesions, the FID EPI sequence suffered from considerable T1 effects, causing problems in the quantification of perfusion data. CONCLUSION: FID EPI sequences were preferred for perfusion MR imaging in patients without strong enhancing lesions, e.g. in ischemia or tumors with intact blood-brain barrier. In patients with suspected strong enhancing lesions, an SE EPI sequence should be used.     

脑转移瘤钆造影增强与磁化传递成像双对比研究

本文搜集经组织学证实的１５例颅内转移瘤病例，采用Ｇｄ－ＤＴＰＡ增强和增强后磁化传递对比技术（ＭＴＣ）相结合的方法，初步探讨了ＭＴＣ在检测脑转移瘤中的价值，发现：（１）ＭＴＣ在低磁场强度下对Ｇｄ－ＤＴＰＡ增强有协同作用；（２）两者结合可进一步发现和明确常规ＳＥ序列成像上没有或可疑的病灶，从而可提高检出率，防止漏检。     

Dual-Echo Interleaved Echo-Planar Imaging of the Brain

An interleaved echo-planar imaging (EPI) technique is described that provides images from 20 sections of the brain at two echo times (27 and 84 ms) in 1:05. Six echoes per image per repetition are collected in 24 repetitions of the pulse sequence. MR images of the brain obtained from five volunteers using the dual-echo EPI sequence, fast spin-echo (FSE), and conventional dual-echo spin-echo were evaluated qualitatively for diagnostic use and quantitatively for relative signal-to-noise ratio (SNR), contrast, and contrast-to-noise ratios (CNR).     

Comparison of arterial spin-labeling techniques and dynamic susceptibility-weighted contrast-enhanced MRI in perfusion imaging of normal brain tissue

OBJECTIVES: To evaluate relative cerebral blood flow (rCBF) in normal brain tissue using arterial spin-labeling (ASL) methods and first-pass dynamic susceptibility-weighted contrast-enhanced (DSC) magnetic resonance imaging (MRI). METHODS: Sixty-two patients with brain metastases were examined on a 1.5 T-system up to 6 times during routine follow-up after stereotactic radiosurgery. Perfusion values in normal gray and white matter were measured using the ASL techniques ITS-FAIR in 38 patients, Q2TIPS in 62 patients, and the first-pass DSC echo-planar (EPI) MRI after bolus administration of gadopentetate dimeglumine in 42 patients. Precision of the ASL sequences was tested in follow-up examinations in 10 healthy volunteers. RESULTS: Perfusion values in normal brain tissue obtained by all sequences correlated well by calculating Pearson's correlation coefficients (P < 0.0001) and remained unchanged after stereotactic radiosurgery as shown by analysis of variance (P > 0.05). CONCLUSION: Both ASL and DSC EPI MRI yield highly comparable perfusion values in normal brain tissue.     

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.     

Contrast media in MR arthrography of the glenohumeral joint: intra-articular gadopentetate vs saline: preliminary results

The purpose of this investigation was to compare gadopentetate and saline as contrast media in MR arthrograms of the glenohumeral joint. In 60 consecutive patients MR arthrograms with either gadopentetate (n = 26) or saline (n = 34) were performed. After injection of gadopentate, 3D gradient-echo (GE) images were obtained (TR 32 ms, TE 10 ms, flip angle 40 °). With saline, double-echo steady-state images (heavily T2-weighted 3D GE images) were obtained (TR 40 ms, TE 9/45 ms, flip angle 40 °). In the last 14 of these patients T2-weighted turbo spin-echo (SE) images were added (TR 2900 ms, TE 96 ms). Contrast-to-noise ratios standardized for imaging times proved to be superior for the gadolinium arthrograms compared with GE and SE saline arthrograms (intra-articular fluid vs subacromial fat: p = 0.0001 and 0.0008; intra-articular fluid vs supraspinatus tendon: p = 0.0001 and 0.046). Using a qualitative scoring system gadolinium arthrograms were superior to saline arthrograms (p < 0.0001 and p < 0.0001). Saline arthrograms in combination with GE and SE sequences are inferior to gadopentetate arthrograms with GE sequences. Received 24 May 1996; Accepted 30 August 1996     

Arterial spin-labeling in routine clinical practice, part 2: hypoperfusion patterns

Arterial spin-labeling (ASL) is a powerful perfusion imaging technique capable of quickly demonstrating both hypo- and hyperperfusion on a global or localized scale in a wide range of disease states. Knowledge of pathophysiologic changes in blood flow and common artifacts inherent to the sequence allows accurate interpretation of ASL when performed as part of a routine clinical imaging protocol. Patterns of hypoperfusion encountered during routine application of ASL perfusion imaging in a large clinical population have not been described. The objective of this review article is to illustrate our experience with a heterogeneous collection of ASL perfusion cases and describe patterns of hypoperfusion. During a period of 1 year, more than 3000 pulsed ASL procedures were performed as a component of routine clinical brain MR imaging evaluation at both 1.5 and 3T. These images were reviewed with respect to image quality and patterns of hypoperfusion in various normal and disease states.