三维增强磁共振造影评估四肢血管病变的价值

三维增强磁共振造影是利用钆造影剂缩短血液弛豫时间的效应产生信号而不依赖自然血流的成像方法,是一种无创伤、无辐射、简便和实用的影像诊断方法。三维增强磁共振造影能够清楚显示靶血管的正常解剖结构和病变部位及其狭窄程度。高质量的三维增强磁共振造影图像依赖于注药后最佳的延时扫描时间、合适的注射速率、注射总量、扫描序列及其参数以及操作者的技巧和熟练程度。三维增强磁共振造影与数字减影血管造影有很好的一致性,是一种有效的、快速的、全面的和准确的造影技术,是四肢血管病变较为理想的检查方法。     

颈动脉三维对比增强磁共振血管成像技术规范化探讨

目的探讨颈动脉三维对比增强磁共振血管成像(3D CE-MRA)技术的规范。方法回顾性分析20例患者颈动脉3D CE-MRA的参数设置、实际操作和图像质量。结果不同对比剂注射方法、扫描方式、对比剂速率,以及是否使用生理盐水对图像质量的影响有显著差异。结论运用高压注射器注射对比剂、采用透视触发技术(主动脉弓显影至最亮时启动扫描)、维持对比剂速率2.0~3.0 mL/s、使用生理盐水维持团注,可提高3D CE-MRA的图像质量。     

Assessment of left atrial volume by contrast enhanced magnetic resonance angiography.

Left atrial (LA) volume is associated with cardiovascular morbidity, particularly atrial fibrillation. Contrast-enhanced magnetic resonance angiography (CE-MRA) visualizes the LA, but the validity of LA volume measurements using this technique has not been evaluated. We performed CE-MRA and cine magnetic resonance (MR) in 18 consecutive patients referred for CE-MRA prior to atrial fibrillation ablation. The CE-MRA LA volumes were compared to cine MR LA volumes at the maximal LA size and at LA end-diastole using linear regression and limits of agreement analysis. The mean cine MR LA volume was 118 +/- 39 mL at maximal LA size and 91 +/- 38 mL at LA end-diastole. Left atrial volume determined by CE-MRA was 93 +/- 38 mL. Although the CE-MRA LA volume had a strong correlation with the maximal cine MR LA volume (R2 = 0.86, p < 0.001), the 95% limits of agreement were relatively wide (-54 to 3 mL). The cine MR LA end-diastolic and CE-MRA LA volumes were more closely correlated (R2 = 0.98, p < 0.001) with narrow 95% limits of agreement (-8 to 11 mL). The CE-MRA LA volumes correspond most closely to LA end-diastolic cine MR LA volumes and may be a useful measure of LA size.     

Contrast enhanced body magnetic resonance angiography

The use of gadolinium contrast for body MRA is reviewed. Considerations for timing of the bolus of contrast are discussed. The utility of this technique is illustrated through clinical examples. Contrast enhanced MRA is rapidly replacing conventional angiography for many applications.     

三维动态增强磁共振血管造影对四肢血管疾病的诊断价值

目的:应用三维动态增强磁共振血管造影对四肢血管疾病进行诊断,并与"金标准"数字减影血管造影结果对比分析,评价其技术方法的价值。方法:选择2004-05/2007-05在北华大学附属医院经手术病理证实的30例四肢血管疾病患者。①用1.5T超导磁共振成像仪(SIEMENS novus1.5T)采集定位像,对兴趣血管注入15mL马根维显(先灵药业有限公司,022H)行三维动态增强磁共振血管造影。②采用Siemens Bicor C形双臂血管造影机,经股动脉采用常规Seldinger法穿刺行数字减影血管造影。③以数字减影血管造影图像为标准,将三维动态增强磁共振血管造影获得的血管图像按照狭窄程度分为4级,狭窄段血管的长度分为3部分。评价2种方法检测测得的血管狭窄程度及狭窄长度的一致性。结果:30例患者的资料均进入结果分析。①数字减影血管造影只观察到与血流相关的信息,而三维动态增强磁共振血管造影能够清楚显示靶血管的正常解剖结构和病变部位,可同时观察到血流、瘤体、骨组织、软组织及其结构关系。②三维动态增强磁共振血管造影测得动脉狭窄程度和长度较数字减影血管造影略高.但二者无显著性差异(P>0.05)。结论:三维动态增强磁共振血管造影对四肢血管病变的诊断与数字减影血管造影有很好的一致性,是一种无创、简便快速的诊断方法,图像清晰,有助于观察血管病变及其与周围结构的关系。     

三维动态增强磁共振血管成像在下肢血管病变中的临床应用

随着磁共振血管成像技术的不断发展成熟,由于其克服了传统的血管造影成像的碘电离辐射并具有无创性及无肾毒性等优越性在临床中受到医生与患者广泛接受与应用,但是由于三维动态增强磁共振血管成像（3D DCE-MRA）还处于不断的研究改善阶段,国内外学者通过各种实验研究不断更新技术并与DSA进行科学比较,期望它能在下肢血管成像中将来能完全取代DSA。本文对3D DCE-MRA成像技术的研究进展及临床应用予以综述。     

3.0T MR全心对比增强冠状动脉成像检测冠心病的可行性

目的 比较3.0T磁共振全心对比增强冠状动脉成像(CE-CMRA)与传统冠状动脉造影(CAG)对可疑冠心病(CAD)检出的能力,探讨临床应用3.0T CE-CMRA的可行性。 方法 对30例可疑CAD患者在1周内先后行CAG和CE-CMRA检查。CE-CMRA检查应用心电门控、呼吸门控、反转回复序列、分段梯度回波序列,以0.3 ml/s速率注入钆贝酸二葡甲胺(0.2 ml/kg)和15 ml生理盐水,延迟60 s开始采集数据。以传统CAG为金标准,计算CE-CMRA的诊断敏感度、特异度和准确率。应用Kappa一致性检验评价两种检查方法的一致性。 结果 成功完成26例CE-CMRA检查, CE-CMRA诊断CAD患者、段落、各支血管的准确率分别为84.62%(22/26)、78.30%(285/364)、87.50%(56/64),阳性预测值分别为81.82%(9/11)、81.05%(124/153)、91.67%(22/24),阴性预测值分别为89.47%(17/19)、80.62%(208/258)、90.32%(56/62)。CE-CMRA对右冠状动脉的显示率为86.15%(112/130);左主干100%(26/26);前降支98.46%(128/130);回旋支83.33%(65/78)。26例CE-CMRA中,17例图像为Ⅳ级,8例为Ⅲ级图像,1例为Ⅱ级图像,无0级和Ⅰ级图像。 结论 3.0T CE-CMRA的图像质量符合诊断要求,可作为检出CAD的一种方法。     

三维对比增强磁共振血管成像对正常颅内静脉系统的显示

目的比较3D-CE MRA、2D-TOF MRA和3D-PC MRA技术对正常颅内静脉不同解剖部位的显示能力.方法28例无颅脑病变的受检者分别行斜冠状位2D-TOF、矢状位3D-PC及矢状位3D-CE MRA检查.3种MRA技术的原始图像均进行最大信号强度投影处理.在最大信号强度投影的图像上对预设的颅内各解剖部位的静脉血管图像质量逐一进行分级比较.结果对颅内上矢状窦、直窦、双侧横窦、双侧乙状窦、大脑中浅静脉及Galen静脉的显示,3D-CE MRA与2D-TOF之间及3D-CE MRA与3D-PC之间分别比较均无显著性差异(P值均＞0.01).3D-CE MRA对下矢状窦、窦汇的显示优于2D-TOF(P值均＜0.01),对大脑上静脉、Trolard静脉、Labbe静脉的显示优于2D-TOF和3D-PC(P值均＜0.01).结论3D-CE MRA能快速提供高质量的颅内静脉结构图像,尤其是对窦汇区静脉结构的显示优于2D-TOFMRA、对大脑皮层浅静脉的显示优于2D-TOF及3D-PC MRA.     

Accelerated free breathing ECG triggered contrast enhanced pulmonary vein magnetic resonance angiography using compressed sensing

Background

To investigate the feasibility of accelerated electrocardiogram (ECG)-triggered contrast enhanced pulmonary vein magnetic resonance angiography (CE-PV MRA) with isotropic spatial resolution using compressed sensing (CS).

Methods

Nineteen patients (59 ± 13 y, 11 M) referred for MR were scanned using the proposed accelerated free breathing ECG-triggered 3D CE-PV MRA sequence (FOV = 340 × 340 × 110 mm³, spatial resolution = 1.5 × 1.5 × 1.5 mm³, acquisition window = 140 ms at mid diastole and CS acceleration factor = 5) and a conventional first-pass breath-hold non ECG-triggered 3D CE-PV MRA sequence. CS data were reconstructed offline using low-dimensional-structure self-learning and thresholding reconstruction (LOST) CS reconstruction. Quantitative analysis of PV sharpness and subjective qualitative analysis of overall image quality were performed using a 4-point scale (1: poor; 4: excellent).

Results

Quantitative PV sharpness was increased using the proposed approach (0.73 ± 0.09 vs. 0.51 ± 0.07 for the conventional CE-PV MRA protocol, p < 0.001). There were no significant differences in the subjective image quality scores between the techniques (3.32 ± 0.94 vs. 3.53 ± 0.77 using the proposed technique).

Conclusions

CS-accelerated free-breathing ECG-triggered CE-PV MRA allows evaluation of PV anatomy with improved sharpness compared to conventional non-ECG gated first-pass CE-PV MRA. This technique may be a valuable alternative for patients in which the first pass CE-PV MRA fails due to inaccurate first pass timing or inability of the patient to perform a 20–25 seconds breath-hold.     

三维动态增强磁共振血管成像评价原位肝移植受体血管

目的探讨三维动态增强磁共振血管成像(3D-DCE-MRA)对原位肝移植(OLT)术前受体血管的评价价值.方法以手术病理为金标准,回顾性分析30例肝移植患者术前的3D-DCE-MRA图像,包括动静脉血管的信噪比、对血管变异的显示及血管管径测量的准确性.结果 30例OLT患者术前3D-DCE-MRA检查均获成功.动脉平均信噪比20.58±3.74,门静脉平均信噪比13.43±4.12;肝动脉解剖变异5例,其中MichelsⅡ型1例、MichelsⅢ型2例、 MichelsⅤ型1例及MichelsⅥ型1例,门静脉高压侧支循环建立17例, 肝动脉轻度狭窄2处,中度以上狭窄4处,腹腔干起始部狭窄1处,第二肝门处静脉系统狭窄3处,3D-DCE-MRA均准确显示.结论 3D-DCE-MRA可以清晰显示肝动脉、门静脉及第二肝门处的肝静脉和下腔静脉.可以对肝动脉的变异和狭窄、门静脉高压侧支循环建立以及第二肝门情况做出准确评价.3D-DCE-MRA可以作为原位肝移植术前受体血管评价的首选检查方法.     

3.0 T磁共振动态增强定量分析鉴别肺部良恶性病变的初步研究

目的探讨动态增强磁共振(dynamic contrast-enhanced magnetic resonance imaging,DCE-MRI)定量分析对鉴别肺部良、恶性病变的诊断价值。材料与方法搜集30例胸部CT发现肺部实性结节或肿块并行DCE-MRI的患者,男13例,女17例,年龄35~70岁。采用并行采集(CAIPIRINHA)、水脂分离Dixon方法及随机轨迹时间分辨成像(time-resolved imaging with stochastic trajectories,TWIST)技术的容积内插值法屏气检查(CAIPIRINHA-Dixon-TWIST volume-interpolated breath-hold examination,CDT-VIBE)序列,应用Tofts模型测量病变区的微血管转运常数(Ktrans)、反流速率常数(Kep)、血管外细胞外容积分数(Ve)和注射对比剂后60 s内对比剂浓度-时间曲线下面积(i AUC)。结果 30例患者中,肺部病变为良性者17例,恶性13例,病变大小在1.1~5.3 cm。恶性病变组Ktrans、Kep、i AUC值高于良性病变组(P0.05)。Ktrans、Kep、i AUC的ROC曲线下面积分别为0.988、0.765、0.806。结论 DCE-MRI的参数Ktrans、Kep、i AUC对肺部良、恶性病变的鉴别诊断具有较高的诊断效能。     

Quantitative contrast enhanced magnetic resonance imaging for the evaluation of peripheral arterial disease: a comparative study versus standard digital angiography

Objective The purpose of this study is to evaluate the accuracy of semiautomated analysis of contrast enhanced magnetic resonance angiography (MRA) in patients who have undergone standard angiographic evaluation for peripheral vascular disease (PVD). Background Magnetic resonance angiography is an important tool for evaluating PVD. Although this technique is both safe and noninvasive, the accuracy and reproducibility of quantitative measurements of disease severity using MRA in the clinical setting have not been fully investigated. Methods 43 lesions in 13 patients who underwent both MRA and digital subtraction angiography (DSA) of iliac and common femoral arteries within 6 months were analyzed using quantitative magnetic resonance angiography (QMRA) and quantitative vascular analysis (QVA). Analysis was repeated by a second operator and by the same operator in approximately 1 month time. Results QMRA underestimated percent diameter stenosis (%DS) compared to measurements made with QVA by 2.47%. Limits of agreement between the two methods were ± 9.14%. Interobserver variability in measurements of %DS were ± 12.58% for QMRA and ± 10.04% for QVA. Intraobserver variability of %DS for QMRA was ± 4.6% and for QVA was ± 8.46%. Conclusions QMRA displays a high level of agreement to QVA when used to determine stenosis severity in iliac and common femoral arteries. Similar levels of interobserver and intraobserver variability are present with each method. Overall, QMRA represents a useful method to quantify severity of PVD.     

Gated thoracic magnetic resonance angiography at 3T: noncontrast versus blood pool contrast

Both noncontrast and contrast-enhanced approaches to gated thoracic magnetic resonance angiography (MRA) for aortic root evaluation have been reported at 3T. We compare qualitative and quantitative image quality measures for the two approaches, and assess the reproducibility of standard aortic measurements. Respiratory and cardiac gated MRA of the chest was performed at 3T in 45 patients: 23 after administration of iron-based blood pool contrast, and 22 without contrast. Image quality was assessed with a 5-point Likert scale, vessel lumen-to-muscle contrast ratios, and vessel wall sharpness. Two reviewers measured the ascending aorta diameter and valve annulus area. Interrater agreement was assessed using Bland–Altman plots and coefficient of variation (CV). Qualitative image quality was better with blood pool contrast in all principal vessels of the chest (mean Likert of 4.20?±?0.79 vs. 2.60?±?0.77, p?<?0.001). Quantitative assessment was also improved with higher contrast ratios in all vessels (5.26?±?3.3 vs. 1.90?±?0.53, p?<?0.001), and greater sharpness of the aortic annulus and ascending aorta (0.70?±?0.16 vs. 0.56?±?0.14 mm^?1, p?<?0.001, and 0.87?±?0.16 vs. 0.62?±?0.16 mm^?1, p?=?0.008, respectively). Reproducibility of measurement was marginally better for the ascending aorta diameter (CV of 2.80 vs. 3.23%), but substantially increased for the aortic valve annulus area with blood pool contrast (CV of 4.93 vs. 7.32%). The use of a blood pool contrast agent for gated thoracic MRA improves image quality compared to a noncontrast technique, and provides more reproducible measurements of the aortic valve annulus area.     

三维动态增强MR血管造影在糖尿病足下肢动脉病变中的应用研究

目的：探讨三维动态增强磁共振血管成像（3D CE-MRA）在糖尿病足（DF）下肢动脉病变的应用价值。材料与方法对15例怀疑有下肢血管病变的DF患者行3D FLASH CE-MRA检查,扫描范围自腹主动脉下段至足背动脉,通过后处理技术获得满意的下肢三维血管树像;1周内同时均行数字减影血管造影（DSA）检查。每段血管的狭窄程度被分为：A级（正常/狭窄程度〈50%）、B级（狭窄程度≥50%）、C级（闭塞）3个级别。以DSA为“金标准”,综合评估CE-MRA的准确性。结果（1）15例3D CE-MRA检查,显示满意的血管率达100%。（2）CE-MRA与DSA对DF下肢动脉病变检出一致性较好（一致性检验,Kappa值=0.944〉0.75, P〈0.05）;两种检查技术对血管狭窄程度A与C级判断一致性较好（Kappa值分别为0.94、0.84,均〉0.75,P均〈0.05）;两种检查技术对B级评估一致性一般（Kappa值为0.608,〈0.75〉0.4,P〈0.05）。（3）3D CE-MRA对DF下肢动脉病变阳性诊断率96.0%,假阳性、假阴性分别为3.3%、2.0%,敏感性、特异性分别为98.0%、96.7%。（4）3D CE-MRA对血管狭窄程度A、B、C级敏感性分别为96.7%、80%、84.6%;特异性分别为98.0%、92.9%、97.1%。结论对DF下肢动脉病变检出、血管狭窄程度的评估尤其是A、C级判断,3D CE-MRA与DSA有很好的一致性,虽无法避免假阳性和假阴性,但CE-MRA敏感性、特异性很高且有无创伤性、无辐射、无肾毒性、快速、对比剂较少等优势,有望取代DSA和CTA,作为DF下肢动脉病变的常规检查方法。     

非对比增强磁共振血管成像

根据是否应用对比剂,磁共振血管成像可以分为两大类．即对比增强磁共振血管成像和单纯依赖血液流动特性而实现的非对比增强磁共振血管成像。对比增强磁共振血管成像的优点是对血管腔的显示更加可靠、对血管狭窄程度的显示比较真实、一次注射对比剂可以显示多部位的动静脉等,这些优点使其在临床应用中逐步替代了非对比增强磁共振血管成像。但其缺点为需要注射对比剂,无法提供血液流动的信息,如无法显示锁骨下动脉窃血时椎动脉的逆向血流^[1-3]。近年来,由于以下几点的发展,使得非对比增强磁共振血管成像技术重新焕发青春。①文献报道使用钆对比剂可能导致严重的不良反应．即肾源性系统性纤维化,特别是对于终末期肾功能衰竭患者^[1.4-5];②磁共振硬件和软件的进步,如并行采集技术,它可以显著减低采集时间^[1,6];③昂贵的对比剂．特别是在日本,这直接导致非对比增强磁共振血管成像技术的迅猛发展n。     

三维增强MR血管造影在颅内动脉瘤诊断中的价值探讨

目的：评价三维增强MR血管造影（3D CE-MRA）在颅内动脉瘤诊断中的价值及准确性。方法：选择51例动脉瘤患者中同时行3D CE-MRA、三维时间飞越法MR血管造影（3D TOF-MRA）检查的27例动脉瘤患者，所有患者经DSA检查确诊。比较3D CE-MRA和3D TOF-MRA在显示动脉瘤及动脉瘤形态、瘤颈、载瘤动脉及瘤腔血栓能力上的优劣。结果：27例患者检出29个动脉瘤，3D CE-MRA和3D TOF-MRA的敏感性分别是100%（29/29），86%（25/29）。在动脉瘤形态，瘤颈形状及载瘤血管的显示上3D CE-MRA优于3D TOF-MRA（P<0.01），瘤腔血栓的显示上二者无差异（P>0.05）。结论：3D CE-MRA是一种快速有效、无创的诊断颅内动脉瘤的方法。     

多层CT动态增强扫描及CT血管成像对Budd-Chiari综合征的评估价值

目的:探讨Budd-Chiari综合征肝脏多层CT动态强化规律及形成机制,分析CT血管成像在Budd-Chiari综合征诊断中的应用价值.方法:选择解放军总医院2004-12/2007-08收治的udd-Chiari综合征患者43例,采用GE Light Speed 16扫描机进行常规行上腹部CT平扫加3期动态增强扫描检查.分析多层CT动态增强扫描图像,并对其相关血管分别以最大密度投影法和多平面重建法进行血管重建.分析其肝脏多层CT动态强化规律,评价多层CT动态增强扫描及CT血管成像技术在判断血管梗阻平面及显示肝内、外侧支循环中的价值.结果:43例患者中,肝静脉阻塞(狭窄)24例(55.8%),下腔静脉阻塞(狭窄)6例(14.0%),肝静脉合并下腔静脉阻塞(狭窄)13例.Budd-Chiari综合征肝实质典型的强化方式表现为首先出现在肝门区和尾状叶的、以肝内门静脉小支为中心的斑片状强化,随时间延迟强化范围逐渐扩大(29例).结论:多层CT动态增强扫描能够准确地反映Budd-Chiari综合征患者肝脏血流动力学变化,结合CT血管成像技术,能够更直观、准确地显示血管梗阻平面.     

3.0T磁共振多站式多期相CE-MRA在外周血管病变中的应用

目的探讨3.0T MR多站式多期相三维增强血管造影(CE-MRA)在外周血管病变中的应用价值。方法23例怀疑腹盆及下肢血管病变的病人。在3.0T MR上,自动移床四段多期相动态扫描,分析CE-MRA的图像质量及其对各种血管病变的显示情况。结果全部病例图像显示清晰。其中19例下肢动脉硬化闭塞症病人的627支血管,MRA诊断重度狭窄和闭塞的敏感度与特异度分别为94%和100%,阳性预测值81%,阴性预测值为99%。与DSA的诊断结果符合率是89%。结论3.0T MR多站式多期相CE-MRA,可获得高信噪比及超高分辨率的下肢动脉及静脉图像。具有安全、无创伤性,能准确诊断外周血管性病变。