提高支架再狭窄探测的血池对比剂增强、高分辨率、稳态MR血管成像

目的本研究的目的是与首过MR血管成像(FP-MRA)对比,评估用高分辨率、稳态的、血池对比剂增强MR血管成像是否能改善支架内病变的显示。用动脉数字减影血管造影(DSA)作为参考标准。方法20例股浅动脉支架置入术后的病人在接受再次干预前进行了MRA检查。股浅动脉的     

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。     

三维对比剂增强MR血管成像对颈部动脉病变的诊断价值

目的　分析三维对比剂增强MR血管成像 (3DCE MRA)显示的颈部动脉常见病变 ;与DSA比较 ,明确 3DCE MRA诊断颈部动脉病变的价值。方法　对 741例超声多普勒怀疑颈部动脉疾病的患者进行 3DCE MRA成像 ,并根据其病变表现总结分类。 2 0 6例病人同时行DSA检查 ,将颈部动脉分为颈总、颈内、颈外、锁骨下及椎动脉 5个部位 ,由 2位放射学专家独立评估DSA及 3DCE MRA血管资料。结果　 3 6 7%病例 (2 72 / 741)显示无异常。 63 2 9% (469/ 741)显示颈部动脉有病变 ,共计 82 7段 ,其中动脉粥样斑块占 3 4 2 2 % (2 83段 ) ,动脉狭窄占 3 4 46% (2 85段 ) ,动脉闭塞占 3 3 8% (2 8段 ) ,动脉发育纤细占 14 87% (12 3段 ) ;动脉开口变异占 3 87% (3 2段 ) ,动脉扭曲占 3 63 % (3 0段 ) ,动脉瘤占 0 72 % (6段 ) ,动脉夹层占 1 2 1% (10段 ) ,肿瘤包绕或推压动脉占 1 45% (12段 ) ,术后复查占2 18% (18段 )。对 2 0 6例的 412段血管与DSA比较 ,3DCE MRA在颈总动脉、颈内动脉及椎动脉的阳性检出率差异有显著性意义 (P <0 0 1) ,主要是对动脉粥样斑块 (2 56段与 2 83段 )和动脉狭窄 (2 58段与 2 85段 )存在一定的高估。但对 412段血管整个样本 ,两种方法在同一部位诊断各种血管病变差异无显著性意义 (P >0 0     

下肢高分辨力3D非对比剂增强、ECG门控、多步MR血管成像与对比增强MR血管成像的对照研究

目的确定怀疑周围血管病变(PVD)病人下肢采用扰相-自旋回波技术非对比剂增强、3D高分辨力、ECG门控、多步MR血管成像(non-ceMRA)的价值,并与1.0mol对比     

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。     

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。     

三维对比剂增强MR门静脉成像与直接门静脉造影术对照

目的通过与直接门静脉造影术的比较，评价三维对比剂增强MR门静脉成像（3D CE MRP）的准确性。方法26例患者行3D CE MRP和直接门静脉造影检查。分析3D CE MRP上门静脉主干、肝内左右分支的开放性和侧支循环发生情况，其结果与直接门静脉造影对照，评价两者符合情况，并分析两者不符的原因。结果3D CE MRP和直接门静脉造影显示门静脉主干的结果完全一致。对肝内门静脉分支，有21例2种检查结果符合，但有5例不符。1例肝右叶巨大肿瘤，3D CE MRP显示门静脉右后支闭塞，但直接门静脉造影显示明显狭窄。3例左叶肝癌患者，3D CE MRP显示门静脉左支闭塞，但直接门静脉造影显示其近段狭窄和远端闭塞。另有1例肝癌患者，3D CE MRP显示门静脉左支矢状段小癌栓，而直接门静脉造影却未能显示。除1例脐静脉重开由于扫描范围较小未显示之外，3D CE MRP显示侧支循环的结果和直接门静脉造影相符。结论多数病例，3D CE MRP的显示结果与直接门静脉造影符合。3D CE MRP在鉴别肝内门静脉分支狭窄或闭塞时有一定限度，而在显示门静脉小栓子方面却有优势。     

CT血管成像和MR血管成像在颅内创伤性动脉瘤中的诊断价值

颅内创伤性动脉瘤（traumatic aneurysm，TA）国内外报道较少，其检查方法多采用数字减影血管造影术（DSA），而C血管成像（CTA）和MR血管成像（MRA）及其临床诊断价值尚未见系统报道。笔者收集近期6例TA患者资料，并对这两种检查方法进行初步探讨。     

比较应用动脉自旋标记MR成像和动态对比增强MR成像无创性测量肾血流量的定量和可重复性研究

目的探讨动脉自旋标记(ASL)MRI和动态对比增强(DCE)MRI的可重复性和定量比较这两种技术测定肾血流量的结果。方法 16名健康志愿者应用这两种方法进行检     

Total-body contrast-enhanced MRA on a short,wide-bore 1.5-T system: intra-individual comparison of Gd-BOPTA and Gd-DOTA

Total-body contrast-enhanced MRA (CE-MRA) provides information of the entire vascular system according to a one-stop-shop approach. Short, wide-bore scanners have not yet been used for total-body CE-MRA, probably due to their restricted field of view in the z-direction. The purpose of this feasibility study is to introduce an image protocol for total-body MRA on a short, wide-bore system. The protocol includes five to six table-moving steps and two injection runs. Two pharmacologically different contrast materials (CM) were applied in ten healthy volunteers in view of possible CM-dependent influences on the protocol outcome (Gd-Bopta, Gd-Dota). Differences consisted of significantly higher CNR with Gd-Bopta with a mean of 73.8 +/- 38.7 versus 69.1 +/- 34.3 (p = 0.008), significantly better arterial visualization values with Gd-Dota with a mean of 1.26 +/- 0.44 versus 1.53 +/- 0.73 (p = 0.003) and a tendency to less venous overlay with Gd-Dota, mean 1.19 +/- 0.44 and 1.34 +/- 0.72, respectively (p = 0.065) (two-tailed Wilcoxon matched-pairs test). Overall 94% of the steps were valued as qualitatively excellent or good. The good results with both CM suggest a transfer to further patient evaluation.     

A comparison of Gd-BOPTA and Gd-DOTA for contrast-enhanced MRI of intracranial tumours

A two-centre intra-individual crossover study was performed in 23 patients with suspected high-grade glioma or metastases to assess and compare the safety and enhancement characteristics of two different MRI contrast media (gadobenate dimeglumine, Gd-BOPTA and gadoterate meglumine, Gd-DOTA) at equivalent doses of 0.1 mmol/kg body weight. T1-weighted spin-echo (SE) and T2-weighted fast SE images were obtained before and T1-weighted images 0, 2, 4, 6, 8 and 15 min after injection. T1-weighted images with magnetisation transfer contrast were acquired 12 min after injection. Qualitative assessment by blinded, off-site readers (reader 1: 19 patients; reader 2: 21) and on-site investigators (23) revealed significant (P 0.005) overall preference for Gd-BOPTA over Gd-DOTA for contrast enhancement (Gd-BOPTA preferred in 18, 15 and 18 cases; Gd-DOTA in 0, 1 and 1 and no preference in 1, 5 and 4; off-site readers 1 and 2, and on-site investigators, respectively). A similar significant preference for Gd-BOPTA was expressed by off-site readers and on-site investigators for lesion-to-brain contrast, lesion delineation, internal lesion structure, and overall image preference. Quantitative assessment by off-site readers revealed significantly (p<0.05) greater lesion enhancement with Gd-BOPTA than with Gd-DOTA at all times from 2 min after injection.     

MR-guided liver biopsy within a short, wide-bore 1.5 Tesla MR system

The purpose of this study was to evaluate the diagnostic efficacy of magnetic resonance (MR)-guided biopsy of focal liver lesions within a short, wide-bore 1.5-T MR system and to determine the duration and accuracy of needle placement using MR fluoroscopy guidance in 25 patients. Accuracy of needle placement was evaluated in two orthogonal planes, and the out-of-plane angle of needle deflection was measured. Needle positioning was characterised subjectively as centred, peripheral, or exterior relative to the lesion. Exterior positioning was corrected by a step-by-step procedure. Surgical resection (n = 6), previous histologies (n = 8), or clinical/radiological follow-up (n = 11) served as the ‘gold standard’. The guidance needle could be placed successfully using MR fluoroscopy in 20 of 25 patients (80%). Needle placement was rated as ‘centred’ in 11 and as ‘peripheral’ in nine patients. Median needle deflection was 2.6 degrees, with a median deviation of 3.4 mm. In five patients, the direct approach failed or was rated as ‘exterior’; therefore, repositioning after needle stabilisation with a stainless-steel stylet was necessary. The diagnostic yield of all biopsies was: sensitivity 95.5%, specificity 100.0% and accuracy 96.0%. In conclusion, MR-guided biopsies in a short, wide-bore MR system yielded highly reliable biopsy results, and in most cases the direct approach with MR fluoroscopy guidance proved to be fast and accurate.     

Time-resolved 3D contrast-enhanced MRA with GRAPPA on a 1.5-T system for imaging of craniocervical vascular disease: initial experience

Introduction: For three-dimensional (3D) imaging with magnetic resonance angiography (MRA) of the cerebral and cervical circulation, both a high temporal and a high spatial resolution with isovolumetric datasets are of interest. In an initial evaluation, we analyzed the potential of contrast-enhanced (CE) time-resolved 3D-MRA as an adjunct for neurovascular MR imaging. Methods: In ten patients with various cerebrovascular disorders and vascularized tumors in the cervical circulation, high-speed MR acquisition using parallel imaging with the GeneRalized Autocalibrating Partially Parallel Acquisitions (GRAPPA) algorithm on a 1.5-T system with a temporal resolution of 1.5 s per dataset and a nearly isovolumetric spatial resolution was applied. The results were assessed and compared with those from conventional MRA and digital subtraction angiography (DSA). Results: CE time-resolved 3D-MRA enabled the visualization and characterization of high-flow arteriovenous shunts in cases of vascular malformations or hypervascularized tumors. In steno-occlusive disease, the method provided valuable additional information about altered vessel perfusion compared to standard MRA techniques such as time-of-flight (TOF) MRA. The use of a nearly isovolumetric voxel size allowed a free-form interrogation of 3D datasets. Its comparatively low spatial resolution was found to be the major limitation. Conclusion: In this preliminary analysis, CE time-resolved 3D-MRA was revealed to be a promising complementary MRA sequence that enabled the visualization of contrast flow dynamics in various types of neurovascular disorders and vascularized cervical tumors.     

213例使用宽口径1.5TMR设备引导下射频消融治疗肝脏病变

目的探讨使用宽口径1.5TMR设备引导下射频消融(RF)治疗肝脏恶性肿瘤的有效性、成功性和安全性。方法在110例病人中,56个原发性肝癌病变和157个肝转移病变接受了157次经皮射频消融治疗。平均病灶直径为20mm(4～54mm)。所有的治疗计划、程序和介入治疗后监测均在宽口径1.5TMR设备下进行。介入治疗后立即行肝脏MR增强扫描检查对技术的成功性进行评估。通过肝脏的动态MR成像,对消融技术治疗1个月后的有效性进行了研究评估,平均随访时间为24.2个月(范围5～44个月)。结果 210/213个病变(98.6%)达到技术成功和技术有效。18/210病变(8.6%)治疗4～28个月后发生肿瘤局部复发浸润。18个病变中的7个取得二次完全消融治疗,其他6例病变行手术治疗。总体射频消融(RF)有效率为93.4%(199/213),整体治疗成功率(包括手术)为96.2%(205/213)。发生2种严重并发症(1.3%)(出血和感染性胆汁瘤)和14种(8.9%)轻微并发症,其中有157个病变接受了干预措施。结论宽口径MR引导下射频消融治疗肝脏病变是一种安全、有效的治疗方法。     

MR-guided radiofrequency ablation using a wide-bore 1.5-T MR system: clinical results of 213 treated liver lesions

Objective

To evaluate the technical effectiveness, technical success and patient safety of MR-guided radiofrequency (RF) ablation of liver malignancies using a wide-bore 1.5-T MR system.

Methods

In 110 patients, 56 primary liver lesions and 157 liver metastases were treated in 157 sessions using percutaneous RF ablation. Mean lesion diameter was 20?mm (range 4–54?mm). All planning, procedural and post-interventional control MR investigations were carried out using a wide-bore 1.5-T MR system. Technical success was assessed by a contrast-enhanced MR liver examination immediately after the intervention. Technique effectiveness was assessed by dynamic hepatic MR study 1?month post ablation; mean follow-up period was 24.2?months (range 5–44).

Results

Technical success and technique effectiveness were achieved in 210/213 lesions (98.6?%). In 18/210 lesions (8.6?%), local tumour progression occurred 4–28?months after therapy. Seven of these 18 lesions were treated in a second session achieving complete ablation, 6 other lesions were referred to surgery. Overall RF effectiveness rate was 199/213 (93.4?%); overall therapy success (including surgery) was 205/213 (96.2?%). Two major complications (1.3?%) (bleeding and infected biloma) and 14 (8.9?%) minor complications occurred subsequent to 157 interventions.

Conclusion

Wide-bore MR-guided RF ablation is a safe and effective treatment option for liver lesions.

Key Points

? Magnetic resonance-guided radiofrequency ablation offers various options for monitoring therapy. ? All steps of RF ablation carried out in 1.5-T wide-bore system. ? Therapeutic decisions were based on T1-weighted imaging. ? Technical success and technical effectiveness were high. ? Local tumour progression rate was 8.6?% over a 24-month mean follow-up.     

MRA of intracranial aneurysm models: a comparison of contrast-enhanced three-dimensional MRA with time-of-flight MRA

PURPOSE: The purpose of our study was to compare contrast-enhanced 3D MR angiography (MRA) using ultrafast spoiled gradient-recalled acquisition in the steady state (SPGR) with 2D and 3D time-of-flight (TOF) MRA for visualization of intracranial lateral saccular aneurysm models. METHOD: We used lateral saccular aneurysm models with a height of 10 mm and neck sizes of 2.5 and 10 mm. Imaging was performed using a 1.5 T MR system with a head coil. Contrast-enhanced 3D MR angiograms were obtained using 3D ultrafast SPGR sequence with and without the MR Smartprep technique. Two-dimensional and 3D TOF MR angiograms were also obtained. RESULTS: Contrast-enhanced multiphase 3D MR angiograms taken every 5 s after injection of contrast medium proved superior to the other MRA techniques for delineating lateral saccular aneurysm models. Contrast-enhanced 3D MRA images taken with inadequate delay after MR Smartprep trigger showed poor visualization of the aneurysm model. CONCLUSION: Use of contrast-enhanced multiphase 3D MRA with ultrafast SPGR with shorter TR and TE resulted in clear images of the lateral saccular aneurysm model.     

MR-guided core biopsy with MR fluoroscopy using a short, wide-bore 1.5-Tesla scanner: feasibility and initial results

PURPOSE: To evaluate MR fluoroscopy in a short, wide-bore 1.5T MRI suitable for near real-time biopsy guidance. MATERIALS AND METHODS: A total of eight consecutive patients underwent MR-guided core biopsy in a 1.5T system with a 70 cm bore diameter. A total of five biopsies were performed in focal liver lesions, three biopsies in soft-tissue tumors. Before biopsy, three different fast MR sequences were compared for image quality (anatomical visibility, lesion visibility, and artifacts), and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. In all cases, an MR-compatible guidance needle was positioned under MR fluoroscopy using the most suitable sequence. RESULTS: In each patient the guidance needle could be placed accurately under MR fluoroscopy without having to remove the patient from the isocenter of the magnet during needle movement. All biopsies were technically successful and appropriate specimens could be obtained. In prebiopsy imaging, a T2-weighted single shot turbo spinecho sequence (half-Fourier acquisition single-shot turbo spin-echo [HASTE]) achieved the best rating for lesion visibility and superior SNR and CNR values. CONCLUSION: Findings of this study demonstrate that MR fluoroscopy for biopsy guidance in a short, wide-bore 1.5T scanner is feasible. This scanner combines the patient access advantages of an open-bore system with the superior image quality and speed of a high-field scanner. In our series, the HASTE sequence was best suited for MR-guidance of biopsies.