多站式三维动态增强磁共振下肢血管造影成像技术进展

随着磁共振血管成像（MRA）技术不断发展成熟,多站式三维动态对比增强血管成像（3D CE MRA）应用于下肢动脉病变检查,可获得高信噪比及高分辩率的下肢血管图像,并具有无辐射、无创性、无肾毒性等优点,成为诊断下肢动脉疾病的重要检查方法,具有广阔临床前景。本文对下肢3D CE MRA的技术进展进行综述。     

SENSE技术在磁共振腹部动态增强血管成像中的应用

目的：探讨磁共振敏感编码技术在腹部动态增强血管成像(DcE—MRA)中的应用优势。方法：将疑有腹部血管疾病的40例患者分为二组，实验组20例使用SENSE技术扫描；另外20例为对照组，直接行DCE—MRA扫描。结果：对照组20例中，13例因患者呼吸配合好，图像清晰，其中5例显示了动、静脉不同时相，8例由于扫描时间长，得到动、静脉均显影的图像。其余7例因屏气配合不好，图像出现伪影，为诊断带来了困难。实验组20例患者由于扫描时间明显缩短，均获得了清晰且不同时相的图像。结论：sENsE技术的使用大大地缩短了扫描时间，使腹部DCE—MRA可不受呼吸影响，并能获得不同时相血管强化图像，明显改善了DcE—MRA影像的质量，提高了诊断准确性。     

三维动态增强磁共振血管成像在诊断肺动脉栓塞中的价值

三维动态增强磁共振血管成像是通过静脉内注射顺磁性对比剂，缩短血液T1，使血液信号增强的血管成像方法。近几年MRI硬软件技术的快速发展，使磁共振血管成像技术日趋完善，尤其在诊断肺动脉栓塞上效果显。就该技术的成像原理、技术进展及对肺栓塞的诊断价值予以综述。     

三维动态增强磁共振血管成像在肝移植术前的应用

 目的探讨三维动态增强磁共振血管成像(3D DCE MRA)三期扫描技术,评价其在肝移植术前的诊断价值.方法对拟进行肝移植的183例患者进行术前3D DCE MRA成像扫描,采用Siemens Symphony 1.5T超导MRI扫描机,圆形极化相控阵体线圈,3D DCE MRA三期(动脉期、门脉期和静脉期)扫描技术,即对所得图像进行综合评价.结果全部病例均获得了满意的血管成像图像,肝动脉可显示2～3级分支,门静脉可显示2～5级分支,肝静脉可显示1～2级分支.183例肝移植患者,5例显示肝动脉变异,其中2例起自肠系膜上动脉,2例直接起自腹腔干,1例起自胃左动脉.单纯肝硬化门脉高压103例,其中,冠状静脉和食道胃底静脉曲张23例、脐周静脉曲张5例、肠系膜静脉曲张2例、脾门周围静脉曲张30例,门静脉玻璃样变性1例;原发性肝癌79例,5例肝动脉包埋、僵直、推移,2例肝内动-静脉瘘,门静脉右支癌栓23例,门静脉左支癌栓7例,门静脉主干癌栓3例,同时发生门静脉左右支癌栓的2例,MRA表现为门静脉呈半月形或杯口形缺损或不显影.7例肝静脉出现栓塞,5例下腔静脉受压推移,1例下腔静脉瘤栓.结论 3D DCE MRA三期扫描能很好的显示肝动脉、门静脉、肝静脉及下腔静脉系统病变,肝移植术前应用3D DCE MRA,基本达到临床要求,是术前血管评估的有效方法.     

移床-血管示踪MR血管成像在下肢动脉疾病中的临床应用

目的研究移床-血管示踪MRA在下肢动脉疾病中的应用价值,探讨移床技术的优势。方法对36例临床疑有下肢动脉疾病的患者行移床-血管示踪三维动态增强MRA检查,其中急性下肢动脉闭塞症5例,检查后行急诊手术,慢性下肢动脉闭塞31例,其中10例行DSA检查。15例可评价病例以DSA或手术结果作为金标准进行效果评价。结果36例病人均满意地显示了完整的下肢动脉血管。将每条下肢分为14个血管节段观察,15例可评价病例共观察420段血管节段,显示可比动脉节段102段。与DSA或手术结果比较,两者诊断符合率为93.14%(95/102),MRA诊断的敏感度为100%,特异度为100%。5例急性下肢动脉闭塞症与手术结果比较,MRA对血管闭塞长度的评价与手术无统计学差异(t=2.251,P>0.05)。结论移床-血管示踪MRA与DSA或手术比较,具有很好的一致性,能全面、准确地评价下肢动脉病变,是一种可靠的、无创的、有应用价值的检查方法。     

动态增强磁共振血管成像技术及应用优势

目的 探讨动态增强磁共振血管成像(DCE MRA)技术要点及临床应用优势。资料与方法 对35例疑有血管性病变的患者，行DCEMRA扫描，最大信号强度投影(MIP)重建。结果35例均获得了清晰的血管图像，其中8例正常，27例异常。结论 DCE MRA为新的MRA技术，克服了常规MRA及对比增强MRA的缺点，成像效果与DSA相仿，因此具有极大的临床应用价值。     

非对比剂增强MR血管成像技术在肝动脉血管成像中的应用价值

【摘要】目的：以CTA为对照,探讨基于多反转空间标记脉冲技术的非对比剂增强MR血管成像技术（SLEEK-MRA）在肝动脉血管成像中的应用价值。方法：37例同时行CTA及SLEEK-MRA检查的临床怀疑肝脏占位患者纳入研究,CTA检查后7天内行SLEEK-MRA检查。由两位腹部影像诊断医师分别对CTA和SLEEK-MRA图像进行独立评估,评估内容包括四分法图像质量主观评价及最大显示分支级别评估。比较CTA与SLEEK-MRA在肝动脉成像图像质量及最大显示分支级别上的差异。结果：两位医师对CTA及SLEEK-MRA图像质量评分的一致性均为良好及以上（Kappa值:CTA为0.645~0.814;SLEEK-MRA为0.633~0.877）。除肝左动脉一级分支和肝右动脉一级分支外,SLEEK-MRA与CTA两种方法在肝总动脉、肝固有动脉、肝左动脉及肝右动脉血管成像图像质量评分上差异均无统计学意义（P值均>0.05）。CTA显示最大分支级别的能力优于SLEEK-MRA（P=0.020）。37例病例中,CTA显示有7例出现肝动脉变异,SLEEK-MRA显示了其中6例。结论：SLEEK-MRA作为一种无创、无辐射、无需使用对比剂的血管成像方法,在肝动脉血管成像上具有一定的应用价值。     

非对比剂增强MR血管成像技术在门静脉成像中的应用

目的：探讨非对比剂增强磁共振血管成像（NCE-MRA）在评估肝脏门静脉解剖中的临床价值,并与 MSCT门静脉成像（MSCTP）进行对照。方法：选择30例受试者分别行 SLEEK 序列 NCE-MRA 和 MSCTA 门静脉成像检查,其中肝硬化10例,肝癌10例,健康体检者10例。由两位医师分别对所有患者的 NCE-MRA 和 MSCTP 门静脉成像质量进行评分（4级评分法）并进行统计学分析。结果：NCE-MRA 组和 MSCTP 组中,门静脉成像质量评分在2分以上者分别占93．3％（28／30）和96．7％（29／30）。两种方法均能显示所有受试者的3级及3级以下的肝内门静脉,符合率为100％（30／30）。2例（6．7％）健康志愿者的门静脉第6级分支在 NCE-MRA 上未显示,而在 CTP 上可以显示;3例（10％）肝硬化门静脉高压患者的门静脉第5级分支在 CTP 上未显示,而在 NCE-MRA 上可以显示;2例（6．7％）肝肿瘤患者门静脉的部分第4级分支在 CTP 上未显示,而在 NCE-MRA 上可以显示。两种方法的门静脉图像质量评分的差异无统计学意义（P ＜0．05）,两位诊断医师对 NCE-MRA 门静脉成像质量评分的一致性较高,Kappa 值为0．95。结论：SLEEK 序列 NCE-MRA是一种无需使用对比剂的非侵入性血管成像方法,能有效地对肝脏门静脉进行评估。     

非对比增强MR血管成像技术发展及应用

近年来,随着MR设备的发展和新序列的开发,非对比增强MR血管成像(NCE-MRA)技术发展迅速,除传统的时间飞跃法和相位对比法外,许多新方法已可用于全身各部位血管成像。NCE-MRA包括血流依赖和非血流依赖两大类成像技术,这些技术联合应用于不同的成像序列。为了提高对NCE-MRA技术的认识,促进该类技术的开发应用,对多种NCE-MRA方法的成像机制、优缺点和临床应用作一综述。     

Aortoiliac and lower extremity arteries: comparison of three-dimensional dynamic contrast-enhanced subtraction MR angiography and conventional angiography

PURPOSE: To determine the clinical feasibility of three-dimensional dynamic contrast agent-enhanced subtraction magnetic resonance (MR) angiography in patients with symptoms of lower extremity ischemia. MATERIALS AND METHODS: Twenty-three patients suspected of having lower extremity ischemia underwent three-dimensional dynamic contrast-enhanced subtraction MR angiography of the aortoiliac arteries and arteries of the lower extremity. As the reference standard, conventional angiography was also performed. For data analysis, the arterial system was divided into 10 segments. Each segment was classified as normal, mildly stenosed, moderately stenosed, severely stenosed, or occluded. RESULTS: At conventional angiography, 83 stenosed segments (14 mildly stenosed, 16 moderately stenosed, 14 severely stenosed, and 39 occluded) were identified in a total of 423 segments. For the segments with more than mild stenosis, MR angiography was 97.1% sensitive and 99.2% specific. CONCLUSION: Three-dimensional dynamic contrast-enhanced subtraction MR angiography has high sensitivity and specificity. This technique is a noninvasive alternative to conventional angiography for screening patients suspected of having lower extremity ischemia.     

三维主动脉增强磁共振造影技术（附32例报告）

目的：探讨三维增强磁共振血管造影（three dimensional contrast enhancement magnetic resonance angiography,3DCEMRA）技术及其临床应用价值。方法：32例动脉瘤病例中男性23例,女性9例。最大年龄为82岁,最小年龄为32岁,平均年龄64岁。所有病例均进行3DCEMRA检查。增强对比剂为钆-喷替酸萄甲胺（Gd-DTPA）。增强扫描前先行横断位FSE序列T1WI和/或T2WI。CEMRA扫描后行横断位FSET1WI。观察指标包括动脉瘤的起始位置、真假性、范围（长度和最宽直径）、有无血栓、动脉瘤周围结构有无异常等。结果：①动脉瘤的位置：32例动脉瘤中,8例为胸主动脉瘤,22例腹主动脉瘤,1例髂血管动脉瘤,1例肠系膜上动脉瘤;②动脉瘤的真假性：25例呈真性,7例呈假性;③动脉瘤的范围：长度范围为25～162mm,平均长度为80.4mm;宽度范围为32～101mm,平均宽度为54.8mm;④伴有血栓情况：12例动脉瘤内可见附壁血栓形成;⑤动脉瘤累及分支情况：1例累及右侧颈总动脉,7例压迫左肾动脉,9例向髂动脉延伸或累及;⑥动脉瘤周围情况：2例动脉瘤可见周围组织炎症表现。结论：3D CE MRA是一种对评价胸腹部大血管动脉瘤的有效微创伤技术。     

Pelvic and lower extremity arterial imaging: diagnostic performance of three-dimensional contrast-enhanced MR angiography

OBJECTIVE: The diagnostic performance of a three-dimensional MR angiography-based strategy was assessed with regard to its ability to characterize the arterial vasculature from the aortic bifurcation to the lower extremity runoff vessels. A single-injection, two-station protocol in combination with a lower-extremity vascular coil was used. SUBJECTS AND METHODS: Both conventional digital subtraction angiography and three-dimensional contrast-enhanced MR angiography with a dedicated peripheral vascular coil were performed in 61 patients with suspected peripheral vascular disease. In a prospective analysis, one reviewer evaluated the digital subtraction angiographic images and a second reviewer evaluated the MR angiographic images; both were unaware of the results of the other imaging technique. Each vascular segment (29 segments per patient) was evaluated for the presence of occlusive vessel disease. The following grading system was applied: 0, normal; 1, vessel irregularity with a luminal reduction of less than 10%; 2, mild stenosis (lumen reduction, 10-49%); 3, severe stenosis (lumen reduction, 50-99%); and 4, occlusion (lumen reduction, 100%). In 11 patients surgical graft patency was assessed. RESULTS: MR angiography provided an image quality comparable with that of digital subtraction angiography. Overall sensitivity and specificity for MR angiography were 92% and 96.6%, respectively, for the detection of hemodynamically significant disease and 92.3% and 99.4%, respectively, for the detection of occlusions. CONCLUSION: Two-station contrast-enhanced three-dimensional MR angiography with a dedicated lower-extremity vascular coil proved effective enough to consider it as a noninvasive alternative to digital subtraction angiography in the assessment of the pelvic and lower extremity arterial vasculature.     

三维增强MR血管成像诊断脑动静脉畸形的价值

目的 评价三维增强MR血管成像（3DCEMRA）及相关MRI对脑动静脉畸形（AVM）的诊断价值。方法 22例脑AVM患者行头颅MRI及3DCEMRA检查，17例同时行DSA检查。3DCEMRA原始图像减影后至工作站用实时三维容积显示技术进行三维重组。结果 22例中19例MRI显示脑AVM特征性流空血管影，3DCEMRA显示明确异常血管团、供血动脉及引流静脉。病灶均位于幕上，单叶13例，跨叶3例，大脑深部3例；单支供血动脉9例，联合供血10例；引流静脉人上矢状窦6例，至大脑深部8例，向脑表面及脑深部均有引流5例。14例3DCEMRA与DSA比较，DSA显示供血动脉37支，引流静脉25支。3DCEMRA结合MRI对异常血管团的定位及立体显示优于DSA，但在一些细节显示上不如DSA；3DCEMRA对供血动脉的显示率为78．4％（29／37），对引流静脉的显示率为84．0％（21／25）。另外，3例DSA发现〈1cm的微小异常血管，但3DCEMRA未见，MRI仅表现为脑内出血灶。结论 3DCEMRA结合MRI对脑AVM能无创性准确定位、定性，并可显示其结构组成，可作为临床高度怀疑脑AVM患者的首选影像检查方法。但在显示某些细节及〈1cm的微小AVM方面仍需DSA检查。     

Hybrid contrast-enhanced MR angiography of pelvic and lower extremity vasculature at 3.0 T: initial experience

Purpose

The objective of this study was to describe contrast-enhanced magnetic resonance angiography (MRA) of the lower extremities at 3.0 T system for assessment of high resolution images in patients with peripheral arterial occlusive disease (PAOD).

Material and methods

21 Patients with suspected PAOD were examined with four-station MRA at a 3.0 T MR system. The MRA protocol consisted of a hybrid technique with two contrast media injections, the first one for visualization of the calf and foot vasculature (non-moving-table technique), the second one for imaging the aortoiliacal and femoral arteries (moving-table technique). For the femoropopliteal and calf station a randomly segmented central k-space ordering (contrast-enhanced timing-robust angiography [CENTRA]) was used. MR-images were analyzed independently by two radiologists with regard to image quality, venous overlap and grade of stenosis. In 6 patients digital subtraction angiography was performed within the following 7 days and evaluated by two radiologists in consensus with regard to the grade of stenosis. The vasculature-tree of each leg was divided in 12 segments, and 3 anatomical regions (iliacal, femoropopliteal, calf/foot).

Results

490 and 488 of 495 arterial segments were visualized with diagnostic image quality by observer 1 and observer 2, respectively. Image quality was excellent in 470 and 457 arterial segments, respectively. Only 4 segments were rendered as non-diagnostic due to venous overlap. Relevant arterial stenoses (50–99%) were detected in 43 and 47 segments by observer 1 and observer 2, 66 and 65 arterial segments, respectively, were interpreted as occluded.

Conclusion

The hybrid MRA protocol at 3.0 T offers high diagnostic quality for the whole peripheral arterial tree without venous contamination at high spatial resolution.     

高时间分辨率三维动态增强磁共振血管造影与CTA在下肢软组织肿块血管评估中的比较

目的:比较高时间分辨率动态增强磁共振血管造影(TWIST-MRA)与CTA在下肢软组织肿块术前血管评估中的价值.方法:62例临床疑似下肢软组织肿块的患者(男36例,女26例,年龄18～80岁,平均40.9岁)同时行下肢TWIST-MRA和CTA检查;由2名具有10年以上阅片经验的影像医师对两者显示供血动脉数量和动静脉畸形的能力进行评判、比较.结果:62例患者中TWIST-MRA显示主要供血动脉的(股浅动脉、股深动脉等)一级分支数量为(1.92±1.66),CTA显示一级分支数量为(1.50±1.45);由于统计数据为非正态分布,故采用配对Wilcoxon秩和检验法,TWIST-MRA显示肿瘤主要供血动脉(股浅动脉、股深动脉等)一级分支数等于CTA者38例;多于CTA者21例;少于CTA者3例,两者具有显著统计学差异(|Z| =3.368,P=0.001).62例患者中TWIST-MRA和CTA显示动静脉瘘分别为34例(34/62)和15例(15/62),两者差异具有统计学意义(x2=12.181,P＜0.001).结论:TWIST-MRA检测供血动脉和动静脉瘘的能力优于CTA.     

Three-dimensional steady-state MR angiography of the lower extremities

Volume steady-state black-blood magnetic resonance imaging was evaluated as a method for depicting lower extremity vasculature. In steady-state imaging, flow has low signal intensity because motion destroys the coherence of transverse magnetization. To optimize image contrast, computations and measurements were obtained for the three-dimensional (3D) GRASS (gradient-recalled acquisition in the steady state) and 3D SSFP (steady-state free precession) sequences and a range of TRs and flip angles to determine optimal vessel-muscle contrast. The best results were achieved with a 3D GRASS sequence with a TR msec/TE msec of 25/5 and a flip angle of 30°. Coronal images of the femoral and popliteal vessels were obtained in healthy volunteers with various fields of view and voxel sizes. Inflow of unsaturated spins from outside the image region, yielding high signal intensity, could be a potential drawback in steady-state black-blood imaging; however, problems can be avoided by using coronal acquisitions and large fields of view. Steady-state black-blood imaging depicts vessels with high accuracy and is faster and free of flow artifacts.