Gadolinium-enhanced magnetic resonance angiography of the abdominal vessels

Summary Contrast enhanced (CE) magnetic resonance angiography (MRA) provides high resolution angiograms within 20–40 sec. The technique is based on the acquisition of heavily T1-weighted threedimensional (3D) gradient-echo data sets (FISP) with ultrashort echo- (< 2 ms) and repetition times (< 5 ms) during the arterial phase of an intravenously injected bolus of a T1-shortening agent such as Gd-DTPA. For MR-angiography of abdominal vessels CE-MRA is better suited than “time-of-flight” (TOF) and phase-contrast (PC) MRA because motional artifacts can be obviated with breath-held acquisitions. We have optimised the technique and evaluated its potential for angiography of the abdominal aorta and its branches as well as the portal vein and its tributaries. Whilst CE-MRA provides reliable diagnostic accuracy in the aorta and the proximal sections of its branches, small peripheral arteries cannot be assessed accurately. The portal vein and its tributaries can often be depicted better with CE-MRA than with conventional angiography but, like conventional angiography, CE-MRA is hampered by slow and reversed flow, conditions under which TOF or “true FISP” MRA may perform bst. We have also investigated FLASH-echo-planar imaging (EPI) hybrid techniques, a further technical development which due to shorter acquisition times of 12–15 sec. allows semi-dynamic imaging of the arterial and venous phase and provide better vessel contrast due to the use of fat-suppression.      

动态增强MRA的临床研究

目的与常规ＭＲＡ比较，并以手术或ＤＳＡ作为金标准，评估动态增强磁共振血管成像（ＤＣＥＭＲＡ）的图像质量和应用价值。方法４０例共１３２条体部血管同时作了常规ＭＲＡ和ＤＣＥＭＲＡ检查，前者以二维时间飞跃法（２ＤＴＯＦ）ＭＲＡ为主，后者以三维（３Ｄ）ＤＣＥＭＲＡ为主，部分病例屏气扫描（２０～３０秒），快速注射ＧｄＤＴＰＡ２０ｍｌ（０．１５～０．２ｍｍｏｌ／ｋｇ），造影剂注射速度和扫描时间依据靶血管的性质、部位、范围而定。结果４０例中３５例发现有血管病变，与手术或其他影像学方法检查结果一致。３０例主动脉弓及弓上分支、腹主动脉、腔静脉及门静脉的显示满意率，２ＤＴＯＦＭＲＡ为４０％，ＤＣＥＭＲＡ为９６％，颈动脉及下肢血管则分别为９０％、７０％。利用配对计数资料χ２检验，前者两种方法有显著性差异（χ２＝１６．６５，Ｐ＜０．００１），后者无显著性差异（精确卡方检验：χ２＝０．５８，Ｐ＞０．０５）。结论ＤＣＥＭＲＡ为新的磁共振血管成像技术，克服了常规ＭＲＡ的许多缺点，尤其对胸腹部血管，两种方法血管显示满意率有极显著性差异。屏气薄层３ＤＤＣＥＭＲＡ技术，几乎达到与ＤＳＡ相仿的结果，其临床应用潜能极大。     

MR angiography of the thoracic vessels

Summary Through the introduction of newly invented high-performance gradient systems to MRI, which enable for echoplanar imaging (EPI), also magnetic resonance angiography (MRA) has gained an entirely new field of applications and techniques. Ultrafast imaging techniques in MRA allow the investigation of larger vascular areas within a single breathhold-period. Artifacts like motion induced signal misregistrations, dephasing or saturation of the vascular signal are minimized by extremely short echo times. The technique thus requires the intravenous application of a contrast media bolus, usually a gadolinium compound, which is in standard clinical use. Coordination of the bolus injection and the timing of the data acquisition is crucial for optimal results. The first pass evaluation of the contrast media resembles CTA to a certain extend. Due to the fast measurement and the high contrast in contrast-enhanced MRA (CE-MRA) new applications and indications are developed like MRA of the pulmonary vessels. The paper offers considerations and trials for optimization of thoracical CE-MRA. Besides parameter constellation also bolus-optimization is described with respect to the dedicated anatomical premises. Investigations on volunteers and on patients build a basis for suggestions on optimized CE-MRA procedures. To date, a final estimation of the clinical value of the new technique cannot be given since ongoing improvements change the optimal protocol frequently and the potential of further developments is high.      

脑动静脉畸形的增强MRA

3D-TOF MRA能明确瘤巢及供血动脉,但由于逐渐饱和效应的影响,小动脉及引流静脉显示不佳。CE MRA不依赖于流动效应。而和 Gd-DTPA导致的 T_1 时间缩短有关。Gd-DTPA能够抵消 3D-TOFMRA的逐渐饱和效应,本文分析了12例AVM增强 3D-TOF MRA表现。并和平扫MRA作了比较,结果表明:增强MRA对瘤巢、供血动脉及引流静脉的显示均有不同程度的提高。     

The value of true-FISP sequence added to conventional gadolinium-enhanced MRA of abdominal aorta and its major branches

To test true-fast imaging with steady-state precession (true-FISP) added to gadolinium-based MR angiography (Gd-MRA) for imaging abdominal aorta and major abdominal vessels, 35 consecutive patients (age 67 ± 11 years) with known or suspected abdominal and/or peripheral vascular disease were studied with sagittal and axial 2D true-FISP during free breathing and coronal 3D fast low-angle shot (FLASH) Gd-MRA (breath-holding, 0.2 mmol/kg of Gd-DOTA at 2 ml/s). We evaluated: suprarenal aorta, celiac trunk, superior mesenteric artery, right renal artery, left renal artery, infrarenal aorta, inferior mesenteric artery, aortic bifurcation/common iliac arteries, lumbar arteries and aortic atheromasia. The possible presence of accessory renal arteries, collateral vasculature and vascular prosthesis/stent was evaluated. A quality four-point score was assigned to each item on both sequences, from 0 (not visible) to 3 (good-to-excellent image quality) and Wilcoxon test was used. Main diagnoses resulted: normal or atheromasic aorta (n = 25); aortic aneurysm (n = 2); patent aorto-iliac surgical prosthesis (n = 2); patent vascular iliac stent (n = 2); aneurysm of iliac artery (n = 1); patent aortic endovascular prosthesis (n = 1); patent aorto-femural bypass (n = 1) and aorto-iliac surgical prosthesis endoleak (n = 1). We also found three patients with accessory renal arteries, two with collateral circulation, and three with surgical aorto-iliac prosthesis. The score of true-FISP (25.9 ± 4.1, median 27) was significantly higher (p = 0.003) than that of Gd-MRA (23.9 ± 3.6, median 24). True-FISP was superior for visualizing inferior mesenteric artery (score 2.5 ± 1.1 vs. 1.0 ± 1.4; p < 0.001) and atheromasic plaques (2.5 ± 1.1 vs. 1.2 ± 1.1; p < 0.001). One collateral vasculature was demonstrated only with Gd-MRA. Summarizing, true-FISP is a power and fast non-breath-hold sequence to be added to Gd-MRA, obtaining an information increase.     

Non-Invasive Follow-up Evaluation of Post-Embolized AVM with Time-Resolved MRA: A Case Report

We report the hemodynamic assessment in a patient with cerebral arteriovenous malformation using time-resolved magnetic resonance angiography (TR-MRA), a non-invasive modality, and catheter-based digital subtraction angiography (DSA), before and after embolization. Comparison of the results showed that TR-MRA produced very fast dynamic images and the findings closely matched those obtained at DSA. For initial work-up and follow-up studies in patients with vascular lesions, TR-MRA and DSA are therefore comparable.     

3.0T MR颅脑的3D-TOF MRA

目的比较3DTOFMRA在3.0T和1.5TMR中的血液-背景对比差异、3.0TMR上应用SENSE技术的3D-TOFMRA血液背景对比差异,探讨3.0TMRA的优势及应用价值。方法15例健康志愿者分别在3.0T和1.5T上行Willis环3D-TOFMRA检查。20例在3.0TMR上行MRA检查的患者选用加SENSE和未加SENSE两种方法。计算原始图像的血液背景对比、血液的信噪比和对比-噪声比。结果15例Willis环的平均血液-背景对比分别为1.5T上为2.5±0.5,3.0T上为4.0±0.2;对比噪声比分别为39.7±6.4和107.6±10.9。未加SENSE和加SENSE两种方法血液-背景对比、对比噪声比分别为4.5±0.2和3.3±0.5、120.2±22.5和72.4±8.5。3.0T远端血管的可见度评分为2.8±0.4,1.5T远端血管的可见度评分1.3±0.8。3.0T背景抑制为0.8±0.4,1.5T为0.6 0.5。结论3.0T上T1时间的增加使其血液-背景的对比明显增加,使在灰质内穿行的远端血管的显示更加清晰。SENSE技术在保证图像空间分辨力的基础上,缩短了扫描时间。使用SENSE技术的3D-TOFMRA是神经血管检查的一种快速的、首选的、可信的方法。     

Time‐resolved lower extremity MRA with temporal interpolation and stochastic spiral trajectories: Preliminary clinical experience

Purpose:

To assess added value of a new time‐resolved technique with temporal interpolation and stochastic spiral trajectory through k‐space and parallel imaging (TR‐MRA) to conventional bolus chase MRA (BC‐MRA) for infragenual peripheral artery evaluation.

Materials and Methods:

An institutional review board‐approved retrospective review of peripheral arterial disease patients was performed. Infragenual TR‐MRA and BC‐MRA were performed in 26 patients over four months. Two readers individually assessed image quality, diagnostic confidence, and stenosis severity and length in 13 defined below knee segments, first with BC‐MRA alone, and then with a combined BC‐MRA and TR‐MRA reading (BC+TR‐MRA). Perceived contribution of TR‐MRA was rated by each reader. The reference standard was a consensus reading of both sequences. Catheter angiographic (CA) correlation was available in 6 patients.

Results:

A total of 646 infragenual segments in 51 extremities were evaluated. Image quality and diagnostic confidence were superior for BC+TR‐MRA compared with BC‐MRA alone (P < 0.001). Adding TR‐MRA improved sensitivity (85.7% versus 80.7%; P < 0.05) and diagnostic accuracy (88.1% versus 85.4%; P < 0.05) for hemodynamically significant stenosis. Venous contamination (0% versus 13.1% segments) and motion (0.9% versus 8.0%) were decreased for BC+TR‐MRA versus BC‐MRA alone, P < 0.01. For BC+TR‐MRA, TR‐MRA was rated more useful than BC‐MRA in 30/51 legs (58.8%). TR‐MRA identified retrograde flow in 5 segments. Where available, there was high concordance between CA and BC+TR‐MRA (91.6%) for stenosis.

Conclusion:

Adding TR‐MRA with temporal interpolation and stochastic spiral trajectories to bolus chase MRA improves image quality, diagnostic confidence and accuracy. It provides hemodynamic information and minimizes venous contamination and patient motion. J. Magn. Reson. Imaging 2010;31:663–672. © 2010 Wiley‐Liss, Inc.     

Assessment of myocardial perfusion by magnetic resonance imaging: on the way to clinical application

Summary Magnetic resonance imaging detects the flow of contrast – enhanced blood and even allows the quantitative assessment of myocardial perfusion. The clinical application of this method is being held back by the difficulties in image evaluation and the limitation of standard techniques to the acquisition of a single slice per heart beat cycle. Recent developments in scanner hardware as well as in image acquisition techniques open up the possibility of assessing myocardial perfusion over the entire heart with a spatial resolution in the range of 2 mm. As an example of such a new scanning strategy, a segmented gradient-echo recalled echo planar imaging sequence with preceding saturation is discussed and results in a patient with an infarction are presented. The clinical use of perfusion assessment covering the entire heart for the diagnosis of coronary artery disease is enhanced by the flexibility of magnetic resonance imaging for the assessment of functional cardiac parameters. Eingegangen am 19. Dezember 1996 Angenommen am 19. Dezember 1996     

磁共振成像在烟雾病诊断中的应用价值探讨

目的：旨在探讨磁共振成像在烟雾病诊断中的临床应用价值。材料和方法：对7例烟雾病病人的MRI和MRA征象进行分析。MRI检查包括应用SE序列T1加权像和T2加权像,MRA检查采用三维时间飞跃法,对源图像做最大强度投影重建血管影像。结果：所有病例的MRI和MRA均表现为双侧颈内动脉末端,大脑中动脉和大脑前动脉狭窄或闭塞,颅底部纤细的侧枝不血管呈网状分布,脑膜中动脉和眼动脉增粗,5例有脑实质内急性或亚急性出血;2例合并脑梗塞。结论：MRI能全面显示脑实质内的各种影象病理改变,MRA更为直观地显示颅内血管改变,MRI与MRA的应用对烟雾病诊断有重要价值。     

3.0T高场磁共振3D-TOF-MRA对头颈部血管变异的评价

目的利用3.0 T高场磁共振三维时间飞跃法(TOF)分析头颈部血管的变异特点。资料与方法回顾性分析1336例头颈部磁共振血管成像(MRA)资料,在后处理工作站分析其血管形态特点。结果 3D-TOF-MRA共检出血管变异506例,占37.9%;其中窗式变异67例;原始三叉动脉6例;椎-基底动脉变异252例;大脑前动脉变异103例;大脑中动脉变异6例;胚胎型大脑后动脉72例;其中多种变异可同时存在。结论 3.0 T高场磁共振3D-TOF-MRA分辨率高,无需对比剂,安全、无创,可清晰显示头颈部血管变异,对临床具有重要的指导价值。     

Stroboscopy and imaging in interdisciplinary diagnosis of early stages of carcinoma of the larynx

Summary The laryngostroboscopy is regarded to be the most important functional investigation in laryngologic and phoniatric diagnostics. She allows an analysis of vocal fold vibrations during phonation. Stroboscopic evaluations permit to early detect infiltrative processes of the vocal folds. Superficial alterations of the mucous membrane that invade into the muscle cause a phonatory “standstill” of the vocal fold in the stroboscopy, i. e. a complete lack of vibratory motion. If such a phonatory standstill persists for more than 2 or 3 weeks, a biopsy via microlaryngoscopy is indicated for diagnostic purposes. In comparison to stroboscopy, imaging techniques are not of such great significance in early laryngeal cancer. But in case of suspected infiltration of the tumor a further diagnostic evaluation with CT or MRI is necessary to detect possible neoplastic invasion of the laryngeal cartilage or of extralaryngeal structures. In this paper, we present the principle of laryngostroboscopy, the examination procedure and the stroboscopic parameters. Case reports of early laryngeal cancer illustrate the interdisciplinary diagnostic procedure with CT, MRI and stroboscopy.      

Imaging diagnosis of the larynx. Normal anatomy and pathological changes

Summary The primary goal of diagnostic imaging of the larynx is analysis of submucosal structures that are not visible by clinical or endoscopic means. Therefore, image analysis of the larynx should only be performed under knowledge of the results of clinical diagnosis. The anatomic relationships of the laryngeal skeleton, the intrinsic structures, and the surrounding soft tissue are presented synoptically.      

CE MRA、MCA和2D TOF MRA对四肢血管性疾病和体外血管狭窄模型的应用研究

目的 通过多种磁共振血管造影（MRA）技术对模拟狭窄血管的体外模型和四肢血管性疾病应用研究分析,评估其临床应用价值和限度。材料与方法 （1）实验研究：对不同狭窄程度、长度的模型行二维时间飞跃法磁共振血管造影（2D TOF MRA）、幅度对比血管造影（MCA）、增强幅度对比血管造影（MCA）、增强幅度对比血管造影9CE MCA）和三维动态增强磁共振血管造影（3D CE MRA）检查,测量并计算狭窄程度、长度和分级准确度。（2）临床应用：对20例怀疑有四肢血管相关性疾病的患者行3D CE MRA、2D TOF MRA和幅度对比MRA（MC MRA）。比较其图像质量和血管显示情况。结果 （1）实验研究：2D TOF MRA、MCA、CE MCA和3D CE MRA对明显狭窄（69％）的分级准确度分别为36.4%、9.1%、18.2%和72.7%,3D CE MRA对明显狭窄（≥50％）的评估优于其他MRA方法（P＜0.001）,但比起真实值仍有明显高估（P＜0.001）。（2）临床应用：2D TOF MRA、MCA和3D CE MRA的动脉显示率分别为92.6％、94.4％和98.1％,以及对12例血管瘤的异常血管显示分别为0例、6例和11例。3D CE MRA均能较好地显示血管狭窄程度、供血血管起源、病变部位及病灶对血管的关系。结论 3D CE MRA无论是图像质量、狭窄程度的评估还是病灶的供血血管及病灶与血管关系的显示具有明显优势,但对狭窄程度的高估仍不可避免。     

烟雾病的MRI和MRA诊断

分析和讨论烟雾病的ＭＲＩ和ＭＲＡ表现及其诊断意义。材料和方法：对９例烟雾病患者进行了ＭＲＩ和ＭＲＡ检查,其中２例进行了ＤＳＡ检查。结果：９例ＭＲＩ上,８例显示脑实质改变包括脑梗死５例,脑萎缩２例,脑室扩大１例。８例中４例显示异常血管流空现象。另１例脑内未见异常．ＭＲＡ均良好地显示了病变血管狭窄和闭塞现象,表现为多支、双侧受累,在大脑中动脉为主,与ＤＳＡ所见相仿。结论：ＭＲＩ结合ＭＲＡ可作为烟雾病诊     

3D DCE-MRA在腹部血管病变中的应用

目的 探讨3D动态增强磁共振血管造影在腹部血管病变中的检查技术及临床应用。方法 搜策18例腹部血管的3DDCE—MRA检查资料，对其影像表现进行总结分析。结果 18例3DDCE—MRA血管均显示满意，表现正常者4例，动脉硬化2例，腹主动脉瘤1例，门脉高压6例，门静脉瘤栓5例，其中2例显示门静脉海绵样变性。结论 3DDCE—MR～无损伤，成像速度快，对腹部大血管的病变能清楚显示，有重要的临床应用价值。     

颅颈部动脉狭窄的增强 MRA与DSA比较研究

目的 评价椭圆形中心K空间编码增强（CE）MRA在颅颈部动脉狭窄性疾病的诊断价值.方法 48例根据临床症状怀疑有颅颈部动脉狭窄患者接受了CE MRA和DSA检查.MRA图像采用MIP、MPR方法重建,范围包含从主动脉弓部到Willis 环的所有的血管.以DSA为标准,MRA和DSA结果通过统计相关系数比较.结果 以是否狭窄为评判点时,MRA和DSA在各段颅颈部动脉取得较好的一致性.以狭窄程度超过70%为评判点时,MRA和DSA在颈动脉部位取得相当高的一致性.CE MRA显示椎-基底动脉,颈动脉终末段,颅内血管方面稍差.结论 椭圆形中心K空间编码CE MRA能有效地筛选出颅颈部动脉狭窄性病变.在颅外颈动脉部位可使大部分患者免于接受DSA检查.在诊断椎-基底动脉,颈动脉终末段,颅内血管狭窄方面的准确度不够,不能替代传统DSA检查.     

胰肾联合移植的MRI和MRA评价

目的：评价MRI和3D增强MRA对胰肾联合移植并发症的诊断价值，并与穿刺活检和DSA对比研究，方法：5位患者5次MR检查在术后7天－2年进行，采用GE1．5T MR机型，成像技术包括轴位和矢状位脂肪抑制SE序列T1WI及FSE序列T2WI，3D增强MRA扫描后行轴位或矢状位脂肪抑制T1WI扫描，以计算胰肾移植物的实增强平均百分率（MPPE）。MRCP及MRU采用单次激发快速自旋回波序列。3D增强MRA采用“Smartprep”技术，其资料均采用最大信号强度投影（MIP）及多平面重建（MPR）进行处理。结果：5例移植胰腺，MRI发现2例正常，1例急性排斥反应，1例慢性排斥反应伴纤维化和1例迟发性胰腺炎。5例移植肾，MRI显示4例正常，1例急性排斥反应伴肾梗死。MPPE能鉴别梗死和其它并发症。3D增强MRA能显示血管并发症，如移植血管狭窄、闭塞、动脉瘤形成或血管连接处狭窄等，其结果与DSA相当。MRCP和MRU能分别显示胰管和尿路情况。结论：MRI和3D增强MRA的联合应用使胰肾联合移植的并发症能清楚显示和诊断。     

MR imaging guidance and monitoring of focal thermotherapies. A review

Summary Minimally invasive thermotherapies for focal tissue destruction on the basis of laser-, microwave-, focused ultrasound-, or cryogen-induced changes of tissue temperature represent an alternative to surgical tissue ablation, particularly in the treatment of tumors. The thermotherapy modalities listed necessitate indirect guidance and monitoring, since they often do not lend themselves to immediate visual control. In the brain, in head and neck tumors, in the liver, and in the prostate, MRI reliably and accurately delineates both the positions of interstitial thermotherapy applicators and – in contrast-enhanced, T 1-weighted images – the perfusion defects in tissue necrosis induced by thermotherapy. The transfer of results of in-vitro and in-vivo model studies to assess interstitial temperature and lesion development during thermotherapy to the actual treatment of patients, however, is still in an initial phase. Further development of both rapid MRI sequences and MRI scanners suited for interventions will show how far treatment systems and guidance systems can be adapted to one another.      

三维对比增强MR血管成像在颈部血管病变中的应用

目的探讨三维对比增强MR颈部血管成像（3D—CE—MRA）的方法及临床应用价值。方法对87例患者行颈部血管3D—CE-MRA检查,双日检查者采用testbolus＋3D—CE—MRA扫描,共检查49例患者,单日检查者采用carebolus＋3D—CE—MRA扫描,共检查38例患者,评价图像质量并分析病变血管情况．结果87例患者采用两种方法扫描图像质量无明显差异,均能满足临床诊断需要,3D—CE—MRA图像清楚显示了血管病变部何肢性质。结论3D—CE—MRA是无创、安全、便捷、可靠的颈部血管病变的检查方法,可以代替诊断性的DSA。