Tim技术3D DCE-MRA诊断下肢动脉狭窄:与DSA对比研究

目的以数字减影血管造影（DSA）为金标准,对比评价Tim（total image matrix）技术三维动态增强磁共振血管成像（3DDCE-MRA）在下肢动脉（腘股段和腘下段）狭窄中的临床应用价值。资料与方法41例可疑下肢动脉狭窄患者,采用Tim线圈、多通道并行采集技术,并结合自动移床及无缝连接方法,行3DDCE-MRA检查。延迟时间采用试验团注（test-bolus）法,对靶血管作最大信号强度投影（MIP）后处理重组。所有病例均在1周内行动脉法DSA（IADSA）检查,对比分析3DDCE-MRA所示的轻度狭窄（≤50%）、显著狭窄（51%-99%）、完全闭塞（100%）的符合情况,并计算显示显著狭窄及完全闭塞的敏感性和特异性。结果图像质量的优良率为95.1%。与IADSA对照,3DDCE-MRA显示腘股动脉段显著狭窄及完全闭塞（狭窄程度〉50%）的敏感性91.1%,特异性92.9%,准确性92.3%;显示腘下动脉段的敏感性82.2%,特异性75.4%,准确性83.9%;显示下肢动脉狭窄总的准确性为87.5%。结论Tim线圈、多通道并行采集技术3DDCE-MRA是一种诊断下肢动脉狭窄的无创、安全、可靠、实用的血管检查方法,对腘股动脉段狭窄的诊断更加可靠,但对细小血管（尤其足部）的分辨率尚有待于进一步提高。     

3D CE-MRA在老年糖尿病病人下肢动脉疾病中的应用进展

糖尿病为老年人的常见病、多发病,其可并发多器官疾病,其中下肢动脉疾病是老年糖尿病病人最常见的慢性并发症之一,临床表现重者可出现下肢缺血性坏疽,甚至有截肢的可能。准确评价下肢动脉疾病对其临床诊断和治疗有重要意义。三维对比增强磁共振血管成像（3D CE-MRA）已经成为综合评价下肢动脉疾病的主要方法,对3D CE-MRA的成像原理及其在老年糖尿病病人下肢动脉疾病中的临床应用进展进行综述。     

透视跟踪技术3DCE-MRA在诊断下肢动脉病变中的应用

目的探讨透视跟踪技术三维动态增强磁共振血管造影(3DCE-MRA)在下肢动脉病变中的临床应用价值。方法在161例疑有下肢血管病变做下肢3 D CE-MRA的患者中随机抽取50例,对其成像表现及均值曲线(mean curve)进行回顾性分析。结果当靶血管感兴趣区(腹主动脉腹腔干水平)对比剂信号强度mean值上升到40～60范围内开始触发扫描,也就是感兴趣区有造影剂显影第4～6s触发扫描能准确地观察3段(下腹及盆腔、大腿、小腿)动脉血管,3段血管充盈饱满并且静脉干扰少。结论透视跟踪技术3 DCE-MRA能较好地显示下肢动脉病变的范围和程度,具有操作简便、快捷、节省造影剂用量等优点,而触发扫描时间点的正确选择更有利于动脉病变的检出,可为临床诊断提供更准确的信息。     

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。     

3D CE MRA对诊断下肢血管病变的应用

目的探讨三维对比增强磁共振血管成像（3DCEMRA）对下肢血管病变诊断的应用价值。方法搜集25例临床怀疑或诊断下肢血管疾病的患者行3DCEMRA检查，并对其影像表现进行分析。结果25例中22例诊断为动脉硬化闭塞症，下肢动脉可见不同程度的狭窄及闭塞，其中11例经手术或DSA证实，另有静脉曲张1例，正常表现为2例。结论3DCEMRA对下肢血管病变的显示具有独特的优势，是一种无创伤性、安全的、准确性高的检查方法，甚至是首选的方法。     

动态增强磁共振血管成像对主动脉疾病的诊断价值

目的的：评价动态增强磁共振血管成像对主动脉疾病的诊断价值及对临床治疗的指导作用。方法：82例怀疑有主动脉疾病的患者，应用动态增强磁共振血管成像技术扫描，并与手术结果和血管造影对照，分析DCEMRA的图像质量及其对血管的显示情况。结果：82例均获得满意图像。DCE、EMRA可清晰地显示主动脉疾病的位置以及血流动态情况。结论：动态增强磁共振血管成像是诊断主动脉疾病准确、快速、无创和首选的影像学检查方法，具有较高的临床应用价值。     

颅内动脉瘤 3D DCE-MRA与DSA对照研究

目的 探讨三维动态增强MR血管造影(3D DCE-MRA)在颅内动脉瘤诊断中的价值. 资料与方法 对39例临床拟诊动脉瘤和常规MRA可疑动脉瘤的患者行3D DCE-MRA,随后行DSA,比较两种方法 对颅内动脉瘤的显示情况. 结果 34例动脉瘤患者中共有动脉瘤41个,3D DCE-MRA对动脉瘤诊断的敏感性为95%,特异性为80%,准确性为85%,3D DCE-MRA与DSA比较,差异无统计学意义(P>0.05). 结论 3D DCE-MRA是一项无创、安全、简便和可靠的诊断颅内动脉瘤的方法,对于颅内较大血管的动脉瘤的显示,可以取代DSA.     

TIM 3DCE-MRA和延迟增强诊断多发性大动脉炎的价值

目的 探讨全景成像矩阵三维对比增强磁共振血管成像(TIM 3DCE-MRA)和延迟增强诊断多发性大动脉炎的价值.资料与方法 对20例多发性大动脉炎患者进行TIM 3DCE-MRA和延迟增强检查,得到全身动脉图像.分析病变动脉的范围、数目、性质和程度及侧支循环形成情况,并将病变血管壁的厚度和强化的程度与活动期大动脉炎的实验室检查结果进行比较.结果 20例患者共检出80支病变动脉节段.其中轻中度狭窄35支、严重狭窄28支、闭塞14支、动脉扩张2支、假性动脉瘤1支、动脉夹层未见.活动期大动脉炎动脉管壁增厚并延迟强化.结论 TIM 3DCE-MRA能全面、直观地显示多发性大动脉炎受累血管的范围、数目、性质和程度以及侧支循环形成情况.增厚的内膜延迟强化,对判断活动期大动脉炎、准确诊断及指导治疗有重要的临床意义.     

3D FIESTA联合3D TOF MRA对三叉神经血管压迫的诊断价值

目的 :探讨MRI 3D循环相位稳态采集快速成像(FIESTA)序列联合3D TOF MRA序列对三叉神经血管压迫的诊断价值。方法:选取以原发性三叉神经痛就诊的患者25例,均行3D FIESTA和3D TOF MRA。由2名有经验的影像诊断医师在不知道临床症状的情况下对图像进行观察,分析2种序列中三叉神经和邻近血管的走行关系,以评价2种序列联合显示神经血管压迫与临床症状的相关性。结果:20例行手术治疗,与手术结果对照,MRI对血管压迫诊断的阳性符合率为78.9%(15/19),另4例为假阳性(21.1%,4/19);1例术前MRI诊断未见明确神经血管压迫者术中得到证实。5例术前MRI诊断无神经血管压迫的患者未行手术治疗。结论:MRI 3D FIESTA联合3D TOF MRA可清晰显示三叉神经的血管压迫情况,且与临床症状具较好相关性,可帮助临床医师进行术前评估。     

CT血管成像技术在下肢动脉疾病中的应用价值

下肢动脉疾病是动脉系统疾病中的常见病，目前彩色多普勒超声、磁共振血管成像、CT血管成像等无创性血管成像技术为诊断及制定外科治疗方案提供重要依据，尤其是随着多层螺旋CT的问世，以其亚秒级的扫描速度、薄的层厚及多种后处理重建方式使CTA成像技术在显示下肢动脉病变方面有独特优势。本文主要阐述有关螺旋CTA成像技术在诊断下肢动脉疾病的应用及三种无创性检查方法的比较。     

3D contrast-enhanced MR angiography of the run-off vessels: value of image subtraction

The diagnostic gain associated with image subtractions was assessed regarding contrast-enhanced 3D magnetic resonance angiography (MRA) image sets of the pelvic and lower extremity arteries. The MRA strategy combined a dedicated vascular coil with a single injection, two-station protocol. Voxel-by-voxel signal intensity subtraction was performed on MRA image sets obtained before and during dynamic infusion of a para-magnetic contrast agent. Non-subtracted and subtracted MRA image sets were assessed for the presence of occlusive (four grades) disease, using DSA as the standard of reference. In addition, SNR and CNR were recorded for each vascular segment on both the non-subtracted and subtracted images. While CNR values of subtracted images exceeded those of non-subtracted images (P < 0.05), there was no difference in diagnostic performance. For the detection of hemodynamically significant disease, non-subtracted and subtracted MRA provided overall sensitivity and specificity of 90.2%/90.3% and 95.1%/95.6%, respectively. Concordance between non-subtracted and subtracted MRA was excellent (Kappa = 0.86).     

Need for background suppression in contrast-enhanced peripheral magnetic resonance angiography.

To determine if background suppression is beneficial for peripheral magnetic resonance angiography (pMRA), nonsubtracted, subtracted, and fat-saturated contrast-enhanced (CE) pMRA were compared in 10 patients with peripheral arterial disease. Signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs), as well as venous enhancement and subjective interpretability, were determined in a station-by-station fashion for each technique. In three patients X-ray angiography was available as a standard of reference. SNRs and CNRs were significantly higher for fat-saturated vs. the other two techniques (P = 0.005). Subjective interpretability was best for subtracted data sets in the lower-leg station. In the iliac station, fat-saturated data sets were considered to have significantly lower interpretability than subtracted data sets. Venous enhancement occurred significantly more often in the lower-leg station with the fat-saturated technique. The value of subtraction depends on the hardware one has available and is a useful tool if dedicated surface coils are used. Background suppression by means of magnitude subtraction leads to the best lower-leg image interpretability. Care must be taken to avoid venous enhancement in the lower-leg station when using fat saturation.     

Contrast-enhanced magnetic resonance angiography in peripheral arterial disease: improving image quality by automated image registration

In peripheral arterial disease, contrast-enhanced MR angiography (MRA) is a noninvasive imaging alternative for catheter-based digital subtraction angiography (DSA). In DSA, final images are generated by subtracting a native mask image from subsequent contrast-enhanced images. Image quality is routinely improved by digitally shifting the mask image prior to subtraction if the patient has moved during angiography. This study investigated whether such image registration may also help to improve the image quality of MRA. In all, 545 MRA examinations of pelvic and leg arteries in patients with symptoms of peripheral arterial disease were studied retrospectively. Standard nonregistered MRA was compared to automatically linear, affine, and warp registered MRA by visual analysis and by three image quality parameters, including vessel detection probability (VDP) of angiographic maximum intensity projections. Most MRA of pelvic and upper leg arteries showed good nonregistered image quality. However, the 15% of lower legs with a body shift of 1 mm or more had relatively low nonregistered image quality, which improved significantly with image registration (VDP gain more than 18%, P < 0.05). The visual analysis gave similar results. In conclusion, image registration can improve image quality of MRA in peripheral arterial disease, especially in the lower legs.     

Calf muscle perfusion at peak exercise in peripheral arterial disease: measurement by first-pass contrast-enhanced magnetic resonance imaging

PURPOSE: To develop a contrast-enhanced magnetic resonance (MR) technique to measure skeletal muscle perfusion in peripheral arterial disease (PAD). MATERIALS AND METHODS: A total of 11 patients (age = 61 +/- 11 years) with mild to moderate symptomatic PAD (ankle-brachial index [ABI] = 0.75 +/- 0.08) and 22 normals were studied using an MR-compatible ergometer. PAD and normal(max) (Nl(max); N = 11) exercised to exhaustion. Nl(low) (N = 11) exercised to the same workload achieved by PAD. At peak exercise, 0.1 mm/kg of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) was infused at 3-4 cm(3)/second followed by a saline flush at the same rate. A dual-contrast gradient echo (GRE) sequence enabled simultaneous acquisition of muscle perfusion and arterial input function (AIF). The perfusion index (PI) was defined as the slope of the time-intensity curve (TIC) in muscle divided by the arterial TIC slope. RESULTS: Median workload was 120 Joules in PAD, 210 Joules in Nl(low), and 698 Joules in Nl(max) (P < 0.001 vs. Nl(low) and PAD). Median PI was 0.29 in PAD (25th and 75th percentiles [%] = 0.20, 0.40), 0.48 in Nl(low) (25th, 75th % = 0.36, 0.62; P < 0.02 vs. PAD), and 0.69 in Nl(max) (25th, 75th % = 0.5, 0.77; P < 0.001 vs. PAD). Area under the ROC-curve for PI differentiating patients from Nl(max) was 0.95 (95% confidence interval [CI] = 0.77-0.99). CONCLUSION: Peak-exercise measurement of lower limb perfusion with dual-contrast, first-pass MR distinguishes PAD from normals. This method may be useful in the study of novel therapies for PAD.     

Vessel‐encoded dynamic magnetic resonance angiography using arterial spin labeling

A new noninvasive MRI method for vessel‐selective angiography is presented. The technique combines vessel‐encoded pseudocontinuous arterial spin labeling with a two‐dimensional dynamic angiographic readout and was used to image the cerebral arteries in healthy volunteers. Time‐of‐flight angiograms were also acquired prior to vessel‐selective dynamic angiography acquisitions in axial, coronal, and/or sagittal planes, using a 3‐T MRI scanner. The latter consisted of a vessel‐encoded pseudocontinuous arterial spin labeling pulse train of 300 or 1000 ms followed by a two‐dimensional thick‐slab flow‐compensated fast low‐angle shot readout combined with a segmented Look‐Locker sampling strategy (temporal resolution = 55 ms). Selective labeling was performed at the level of the neck to generate individual angiograms for both right and left internal carotid and vertebral arteries. Individual vessel angiograms were reconstructed using a bayesian inference method. The vessel‐selective dynamic angiograms obtained were consistent with the time‐of‐flight images, and the longer of the two vessel‐encoded pseudocontinuous arterial spin labeling pulse train durations tested (1000 ms) was found to give better distal vessel visibility. This technique provides highly selective angiograms quickly and noninvasively that could potentially be used in place of intra‐arterial x‐ray angiography for larger vessels. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Use of a three-station phased array coil to improve peripheral contrast-enhanced magnetic resonance angiography

PURPOSE: To explore the imaging capabilities of a new commercially available, three-station, 129-cm long, 12-element phased array coil for contrast-enhanced magnetic resonance angiography (CE-MRA) in patients with symptomatic peripheral arterial occlusive disease. MATERIALS AND METHODS: Nineteen patients, referred for peripheral CE-MRA, were evaluated using the new three-station coil. For each station four coil elements (two anterior and two posterior to the patient) were used. The expected improvements in signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were used to improve spatial resolution and increase anatomic coverage for the distal two stations compared to our previous protocol. Images obtained in the 19 patients imaged with the new coil were compared to those of the last 19 patients scanned without the use of the new coil. Differences in image quality before vs. after the availability of the new coil were compared in terms of SNR and CNR, subjective interpretability score (SIS), degree of venous enhancement, and anatomic coverage. Images were interpreted by two experienced observers, blinded for imaging technique and each other's results. RESULTS: Use of the coil enabled acquisition of high resolution peripheral vasculature images in all cases and allowed for substantially smaller voxel sizes (thighs: 5.3 vs. 8.4 mm(3) [-37%]; legs: 1.8 vs. 8.0 mm3 [-78%]) and much shorter acquisition durations in the aortoiliac and thigh stations (aortoiliac: 16 vs. 27 seconds [-41%]; thighs: 11 vs. 23 seconds [-52%]). Acquisition duration in the leg station was prolonged (68 vs. 29 seconds [+134%]). SNR and CNR were significantly higher only in the aortoiliac station using the three-station coil (both: P < 0.001). There were no significant differences in SIS for the aortoiliac and thigh stations (aortoiliac station: observer 1: P = 0.16, observer 2: P = 0.19; thigh station: both observers: P = 0.27). Images acquired with the new coil had significantly higher SIS for the leg station (both observers: P = 0.004). There were no significant differences in venous enhancement between the two protocols for any of the stations (all P > 0.11). In 12/12 (100%) requested cases the entire pedal arch was depicted using the new coil, whereas this was not possible with the old protocol. CONCLUSION: The new three-station dedicated peripheral vascular coil allows for much higher resolution imaging in the thigh and leg stations with greater anatomic coverage and substantially improves peripheral MRA quality of the lower leg vasculature.     

Vessel‐encoded dynamic magnetic resonance angiography using arterial spin labeling

A new noninvasive MRI method for vessel selective angiography is presented. The technique combines vessel‐encoded pseudocontinuous arterial spin labeling with a two‐dimensional dynamic angiographic readout and was used to image the cerebral arteries in healthy volunteers. Time‐of‐flight angiograms were also acquired prior to vessel‐selective dynamic angiography acquisitions in axial, coronal, and/or sagittal planes, using a 3‐T MRI scanner. The latter consisted of a vessel‐encoded pseudocontinuous arterial spin labeling pulse train of 300 or 1000 ms followed by a two‐dimensional thick‐slab flow‐compensated fast low angle shot readout combined with a segmented Look‐Locker sampling strategy (temporal resolution = 55 ms). Selective labeling was performed at the level of the neck to generate individual angiograms for both right and left internal carotid and vertebral arteries. Individual vessel angiograms were reconstructed using a bayesian inference method. The vessel‐selective dynamic angiograms obtained were consistent with the time‐of‐flight images, and the longer of the two vessel‐encoded pseudocontinuous arterial spin labeling pulse train durations tested (1000 ms) was found to give better distal vessel visibility. This technique provides highly selective angiograms quickly and noninvasively that could potentially be used in place of intra‐arterial x‐ray angiography for larger vessels. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

磁共振断层血管成像对原发性三叉神经痛的诊断价值

目的：探讨磁共振断层血管成像(MRTA)对原发性三叉神经痛(ITN)患者神经血管关系的诊断价值及可靠性。方法回顾性分析280例 ITN 患者的临床及 MR 资料,并与手术结果进行盲法对照。结果280例 ITN 患侧神经血管接触、可疑接触或压迫共267例(阳性率95.3%),健侧有66例(假阳性率23.6%);120例手术者,术中发现神经血管接触或压迫118例。患侧与健侧神经血管接触或压迫比较差异有统计学意义(P <0.05)。以手术结果为金标准,MRTA 诊断神经血管接触或压迫的特异度、灵敏度、诊断符合率分别为100%,96.6%,96.7%。结论MRTA 能可靠地显示 ITN 神经血管的关系,其诊断灵敏度和准确率高,对ITN 病因诊断和手术治疗提供客观的依据。     

磁共振动态增强扫描诊断乳腺病变的应用价值

 目的 探讨磁共振动态增强扫描诊断乳腺病变的应用价值.方法 对40例乳腺疾病患者(33个良性病灶,24个恶性病灶)分别进行磁共振平扫和动态增强扫描检查,分析病灶强化的形态特征,测量动态增强的时间-信号强度曲线分布类型、峰值时间和早期增强率.结果 多数病灶在磁共振平扫时未被检出,结合增强后的形态特征对乳腺癌的检出敏感性为75.0%,特异性为69.7%,准确性为71.9%.良、恶性病灶时间-信号强度曲线、峰值时间及早期增强率分布的差异均有统计学意义(P<0.01),诊断敏感性分别为91.7%、87.5%和75.0%,特异性分别为87.9%、87.9%和84.8%,准确性分别为89.5%、87.7%和80.7%.联合上述指标诊断乳腺癌的敏感性为95.8%,特异性87.9%,准确性为91.2%.结论 时间-信号强度曲线、峰值时间及早期增强率在乳腺良、恶性病变诊断中具有较高的敏感性和特异性,结合增强的形态特征,对乳腺病变的诊断及鉴别诊断有重要价值.