3.0 T高分辨率自由呼吸导航全心冠状动脉成像初步研究

目的前瞻性评价3．0T高分辨率自由呼吸导航全心冠状动脉成像的临床应用价值。资料与方法68例临床疑为冠心病的患者接受了3．0TMRA全心冠状动脉检查,采用向量心电门控（VCG）和自由呼吸导航技术,自由呼吸状态下成像。后处理使用3D容积再现（VR）技术和“肥皂泡（Soap-Bubble）”曲面重组技术进行全心冠状动脉重建,分析冠状动脉的走行、狭窄的原因及程度,并与其中26例同期开展了冠状动脉血管造影的患者进行了对比,分析3,0T全心冠状动脉MRA评估冠状动脉狭窄的临床意义。结果68例受检者中,64例获得了满意的检查结果（94％）。发现先天性冠状动脉变异1例,冠状动脉壁斑块形成49例,敏感性为87％,特异性为73％,阳性预测值为81％,阴性预测值为80％。所有病例的检查时间少于30min。3DVR全心冠状动脉重建能完整地再现冠状动脉树,观察冠状动脉的走行,发现冠状动脉先天性变异、主干局部变细以及中断等;“Soap—Bubble”则能够分别测量冠状动脉每一支狭窄的程度,分析狭窄的原因。结论自由呼吸全心冠状动脉MRA能够成功抑制心肌运动,增强冠状动脉血管与周围组织的对比度,无创性地进行三维冠状动脉成像．初步评价冠状动脉主干近、中段狭窄程度和原因．     

全心冠状动脉磁共振成像初步探讨

目的：探讨自由呼吸导航全心冠状动脉磁共振成像（CMRA）心率对成像效果的影响。方法：对28例正常者,用自由呼吸导航触发3D-TFE序列行全心冠状动脉成像,用＂Soap Bubble＂软件进行冠状动脉曲面重建;以显示冠状动脉的节段数及图像质量为评价指标,分析比较不同心率对成像效果的影响。结果：28例中显示冠状动脉112支208段。不同心率冠状动脉显示节段数差异有统计学意义,当心率〈70次/min时各支冠状动脉主干近、中、远段均可良好显示。图像质量一级17例,二级5例,三级3例,四级2例,五级1例。不同心率的图像质量差异有统计学意义（P〈0.05）,当心率〈70次/min时图像质量较好。结论：自由呼吸导航全心CMRA的成像效果与心率有关,心率慢时,冠状动脉各支、段显示较完整,图像质量也较好。     

呼吸导航回波触发冠状动脉磁共振成像

目的:评价呼吸导航回波触发的冠状动脉MRA的效率以及心律和心率对图像质量的影响。材料和方法:17例健康志愿者,用导航回波触发3DSSFP序列进行冠状动脉成像,用自动窗位选择相位排列技术(PAWS)导航回波使膈肌触发采样窗宽为3mm,测量冠状动脉的长度,分析图像质量和心率、心律及呼吸的关系。结果:各冠状动脉主支的长度分别为:右冠状动脉11.6±2.0cm,左主干2.4±0.4cm,左前降支9.0±1.2cm,左回旋支5.0±0.8cm;PAWS的触发效率为37.7%,单次采样耗时6.6±1.0min;图像质量与呼吸方式无关,随着心率增快和心律不规则而降低。结论:PAWS导航回波触发的3DSSFP序列可以很好地控制冠状动脉MRA时的呼吸运动,但是需要提高成像效率以控制心脏运动。     

磁共振自由呼吸冠状动脉血管成像技术的初步探讨

目的:探讨自由呼吸状态下运用超快速平衡式梯度回波序列(sBTFE/3D/NAVI)进行磁共振冠状动脉血管成像技术的可靠性.方法:20例健康志愿者运用sBTFE/3D/NAVI,结合呼吸导航技术,自由呼吸状态下对左右冠状动脉分别扫描,经MIP后处理获得冠状动脉图像.观察冠状动脉的显示率,测量各冠状动脉的显示长度及心肌,冠脉的信号强度及信噪比.结果:20例受检者均完成检查,右冠状动脉、左冠状动脉主干、前降支全部显示;左冠状动脉回旋支显示良好18例(90%).冠状动脉图像的信噪比为37.35±6.32,心肌组织的信噪比为20.03±7.25,两者比较有显著性差异(P＜0.01).结论:自由呼吸sBTFE/3D/NAVI冠脉成像方法显示成功率高,图像信噪比好,可作为不能屏气患者心脏冠脉检查的一种无创性手段.     

导航技术三维对比剂增强磁共振冠状动脉成像

目的评价导航技术三维对比剂增强磁共振冠状动脉成像的应用价值。方法应用导航技术三维对比剂增强磁共振血管成像方法,对20例受检者分别进行左、右冠状动脉成像,经后处理获得左、右冠状动脉血管图像。应用信噪比和对比噪声比评价增强前后的冠状动脉图像,并对冠状动脉主干及其主要分支的显示情况进行评价。结果(1)对获得成功的18例冠状动脉图像进行评价,增强前冠状动脉图像的信噪比为26.37±7.02,对比噪声比为14.76±6.97;增强后冠状动脉图像的信噪比为38.87±11.62,对比噪声比为33.72±10.80,经统计学比较,信噪比和对比噪声比增强前后的差异有统计学意义(t=2.91,4.62;P<0.05)。(2)对比剂增强后左、右及左回旋支冠状动脉近中段的显示率为100%,远侧段的显示率分别为94.4%、88.8%、77.8%。结论导航技术三维对比剂增强磁共振冠状动脉成像有较高的信噪比和对比噪声比,应用于临床尚需进一步的对照研究。     

GRAPPA技术在呼吸导航磁共振冠脉成像中的应用

目的:评价GRAPPA技术在呼吸导航磁共振冠脉成像中的应用价值.方法:时19例志愿者使用和不使用GRAPPA技术行右冠脉靶容积扫描,并使用GRAPPA技术行全心扫描.经后处理得到冠脉图像,从扫描时间、信噪比、对比噪声比、图像质量方面评价应用GRAPPA前后的图像;评价冠脉主要分支的显示情况.结果:GRAPPA技术应用前的扫描时间为(7.67±1.24)min、信蹂比为35.89±4.64、对比噪声比为20.35±4.27,应用后分别为(4.65±1.25)min、29.73±4.18、16.42±3.77,三者差异有统计学意义;图像评分差别无统计学意义.靶容积扫描和全心扫描对右冠脉近中段的显示率分别为94.7%和93.3%,对右冠脉远段显示率分别为78.9%和86.7%,全心扫描对左主干及前降支、回旋支近中段显示率为93.3%,前降支及左回旋支远段为86.7%和80.0%.结论:GRAPPA技术可缩短呼吸导航磁共振冠脉成像(41±13)%的扫描时间(加速因子为2),获得良好的冠状动脉图像,应用GRAPPA技术可完成全心扫描,与靶容积扫描相比,具有更好的应用前景.     

3 T MR呼吸导航回波触发全心冠状动脉成像

目的探讨3TMR呼吸导航回波触发的全心冠状动脉MR成像（WH-CMRA）技术对冠状动脉的显示能力和图像质量。方法92名志愿者接受了3TMR呼吸导航回波触发的WH-CMRA检查，使用T2预备的快速梯度回波（TFE）序列采集。按目测法将图像质量分为0～Ⅳ级，并结合冠状动脉各主要分支的长度、直径和血管锐利度进行评判。分析呼吸、心率和导航回波的采集效率对成像质量的影响，评价呼吸导航回波触发WH-CMRA对冠状动脉主要分支的显示效果。结果92名受检者的图像质量评价为Ⅳ级28名，Ⅲ级53名，Ⅱ级9名，Ⅰ级2名，扫描成功率为88％（81／92）。心率≤75次／min，图像质量20名为Ⅳ级，锐利度为（48±11）％；心率〉75次／min，图像质量34名为Ⅲ级，锐利度为（33±15）％，心率的快慢和图像质量呈负相关（r=-0．726，P〈0．05）。呼吸模式和图像质量无明显相关性（r=0．215，P〉0．05）。结论3TWH-CMRA技术可以实现自由呼吸下的全心冠状动脉成像，但图像质量受到心率的限制。     

3.0T磁共振全心冠状动脉成像对冠心病的诊断价值

目的 探讨3.0T磁共振对比剂增强的全心冠状动脉成像在冠心病诊断中的价值.方法 对51例冠心病患者行心脏磁共振检查,包括自由呼吸门控下的全心增强冠状动脉成像、静息心肌灌注和心肌延迟强化成像.结果 本组51例患者中46例成功完成了全心增强冠状动脉成像.在以患者为基础的分析中,全心磁共振血管造影(MRCA)诊断冠状动脉显著...     

采用自动呼吸导航对比增强技术行全心冠状动脉MR血管成像的初步研究

正目的评估采用自动呼吸导航技术行全心冠状动脉MR血管成像在心脏与冠状动脉疾病诊断中的效能。材料与方法本研究获得机构审查委员会批准,所有志愿者均签     

3.0T高场MR全心冠状动脉成像的初步研究

冠心病(CAD)是当今人类首要的致死病因之一.常规的X线冠状动脉造影(CAG)是目前检测CAD的金标准.但是,常规CAG是一种有创且昂贵的检查方法,存在有发生严重并发症的可能[1],而这些检查中仅有1/3患者需要联合进行介入治疗.因此,对于那些低度或者中度的CAD患病风险的患者来说,需要一种无创的检查方法.     

3.0 T非增强全心冠状动脉MR成像评价冠状动脉狭窄的初步研究

目的 评价3.0T非增强全心冠状动脉MR血管成像(CMRA)诊断冠状动脉狭窄的临床价值.方法 对33例冠状动脉CT血管成像(CCTA)诊断冠状动脉有意义狭窄(＞50％)且拟行冠状动脉造影(CAG)的患者行冠状动脉MR血管成像(CMRA)检查.应用3.0T扫描仪及32通道成像线圈,采用非对比增强、心电门控触发、呼吸导航、T2预置脉冲以及脂肪抑制的三维梯度回波序列.利用美托洛尔降低心率至＜ 80次/min.采用配对样本Wilcoxon秩检验分析CMRA及CCTA在冠状动脉近中段及远段评分的差异性.以CAG结果为金标准,评价CMRA诊断冠状动脉近中段＞50％狭窄的准确性以及与CCTA的一致性.结果 33例患者中30例成功完成CMRA扫描,CMRA及CCTA 在冠状动脉近中段的评分相近[CMRA:(3.49±0.61)分,CCTA:(3.56±0.55)分,Z=-1.715,P＞0.05],CCTA评价冠状动脉远段明显优于CMRA[CMRA:(2.44±0.76)分,CCTA:(3.23±0.60)分,Z=-6.159,P＜0.05].CMRA及CCTA在以段为基础诊断冠状动脉近中段＞50％狭窄的一致性良好(Kappa=0.779,P＜0.05).CMRA诊断的敏感度、特异度、阳性预测值及阴性预测值分别为84.1％ (37/44)、85.8％ (115/134)、66.1％(37/56)、94.3％ (115/122),CCTA分别为88.6％ (39/44)、89.6％ (120/134)、73.6％ (39/53)、96.0％ (120/125).结论 3.0T非增强全心CMRA及CCTA诊断冠状动脉近中段狭窄的准确性相似,但CMRA诊断冠状动脉远段的狭窄需进一步深入研究.     

Three-dimensional high-resolution fast spin-echo coronary magnetic resonance angiography.

Due to SNR constraints, current "bright-blood" 3D coronary MRA approaches still suffer from limited spatial resolution when compared to conventional x-ray coronary angiography. Recent 2D fast spin-echo black-blood techniques maximize signal for coronary MRA at no loss in image spatial resolution. This suggests that the extension of black-blood coronary MRA with a 3D imaging technique would allow for a further signal increase, which may be traded for an improved spatial resolution. Therefore, a dual-inversion 3D fast spin-echo imaging sequence and real-time navigator technology were combined for high-resolution free-breathing black-blood coronary MRA. In-plane image resolution below 400 microm was obtained. Magn Reson Med 45:206-211, 2001.     

Compression belt for navigator-triggered trueFISP whole-heart coronary magnetic resonance angiography: study in healthy volunteers.

PURPOSE: To evaluate in healthy volunteers the usefulness of an abdominal compression belt in reducing acquisition time by stabilizing respiratory motion during whole-heart coronary magnetic resonance angiography (WHCMRA) using conventional navigator triggering. METHODS: In 10 healthy volunteers, we performed free-breathing 3-dimensional segmented true fast imaging with steady-state precession (trueFISP) WHCMRA using conventional navigator triggering without motion-adapted gating. We acquired images with the abdominal compression belt rolled tightly around the upper abdomen and without the belt. We compared image acquisition time, navigator efficiency, and visible length of coronary arteries using paired t-test and subjective image quality on a 4-point scale (1, poor; 4, excellent) using Wilcoxon signed-rank test. RESULTS: There were no statistically significant differences for mean acquisition time (11.5+/-5.0 vs. 9.3+/-2.4 min, P=0.150); navigator efficiency (38.7+/-13.6 vs. 42.8+/-11.0%, P=0.336); mean overall visible length of the coronary arteries (99.7+/-22.7 vs. 105.0+/-16.5 mm, P=0.530); or mean overall subjective image quality (2.5 vs. 2.7, P=0.297) between results obtained with and without the abdominal compression belt. CONCLUSION: In this small group of healthy volunteers, the use of an abdominal compression belt did not reduce image acquisition time or improve image quality in trueFISP WHCMRA using conventional navigator triggering; however, the technique's feasibility requires additional consideration using other navigator-triggering methods for patients with irregular respiratory cycles.     

Combined high-resolution and real-time imaging: a technical feasibility study on coronary magnetic resonance angiography

PURPOSE: To check the bioeffects of the components of magnetic resonance imaging (MRI). MRI is based on an assumed harmless interaction between certain nuclei in the body when placed in a strong magnetic field and radio wave fields. There are three key factors actuating on the examining body: a powerful static magnetic field (SMF), magnetic gradient fields (MGFs), and pulsed radiofrequency (RF) radiation. MATERIALS AND METHODS: In vitro cells (L-132 cells) were used as biosensors, and different cellular compounds were used as biomarkers (heat shock proteins [HSPs] and their messenger ribonucleic acids [mRNAs], calcium, and adenosine-3',5'-cyclic monophosphate [cAMP]). The biosensors were placed in the bore of a 1.5-T MRI machine and the different electromagnetic fields were operated. RESULTS: HSPs and their mRNAs and cAMP did not respond to SMF, MGFs, or RF radiation. RF radiation increased cytosolic calcium concentration (18%, P < 0.05). CONCLUSION: Although MRI procedures do not induce any cellular stress response, it may cause an unfathomable calcium increase in vitro. Although the in vitro experimental conditions are not totally comparable to clinical situations, the usefulness of the in vivo biological dosimetry, circulating leukocytes as biosensors, and HSPs and/or calcium as biomarkers is suggested.     

Prevalence study of proximal vertebral artery stenosis using high-resolution contrast-enhanced magnetic resonance angiography

PURPOSE: To evaluate the prevalence of proximal vertebral artery stenosis, compared wiith those of the distal vertebral/basilar artery and extracranial internal carotid artery, in a large population of stroke and non-stroke patients. MATERIAL AND METHODS: Nine-hundred-and-thirty-five patients who underwent high-resolution contrast-enhanced magnetic resonance angiography in a regional general hospital were categorized into six groups based on neurological symptoms and disease: an asymptomatic group (n = 182), a minor symptom group with headache or dizziness (n = 519), a cardiac group with coronary artery steno-occlusive disease (n = 15), a hemorrhagic group with old cerebral hemorrhage (n=26), an anterior circulation infarct group (n = 121), and posterior circulation infarct group (n = 72). Prevalence of stenosis of the proximal vertebral artery, distal vertebral/basilar artery, and internal carotid artery was analyzed. RESULTS: The prevalence of stenosis of the proximal vertebral artery, distal vertebral/ basilar artery, and internal carotid artery was 12.9%, 5.5%, and 7.2%, respectively, in the study population, and rose as the age increased (P < 0.0001 for all arteries). The prevalence of stenosis of the proximal vertebral artery, distal vertebral/basilar artery, and internal carotid artery was 3.3%, 0.5%, and 1.1%, respectively, in the asymptomatic group; 8.3%, 2.1%, and 3.7%, respectively, in the minor symptom group; 13.3%, 6.7% and 6.7%, respectively, in the cardiac group; 19.2%, 7.7%, and 7.7%, respectively, in the hemorrhagic group; 27.3%, 8.3%, and 25.6%, respectively, in the anterior circulation infarct group; and 44.4%, 36.1%, and 16.7%, respectively, in the posterior circulation infarct group. This increasing tendency of stenosis accordingly was statistically significant (P < 0.0001 for all arteries). CONCLUSION: The prevalence of proximal vertebral artery stenosis was highest, compared with those of the distal vertebral/basilar artery and internal carotid artery, although the clinical significance of proximal vertebral artery stenosis should be investigated in further studies.     

Whole-heart coronary magnetic resonance angiography: contrast-enhanced high-resolution, time-resolved 3D imaging

OBJECTIVES: To test the feasibility and performance of a 4D magnetic resonance coronary angiography sequence compared with conventional inversion recovery (IR) prepared gradient echo imaging. MATERIALS AND METHODS: A 4D sequence with 100 milliseconds temporal resolution was implemented on a 1.5 T system. Five minipigs were examined after administration of very small superparamagnetic iron oxide particles. Coronary angiographies with an isotropic resolution of 0.82 mm were performed in the pigs using 4D and IR sequences. RESULTS: The 4D sequence allowed visualization of the coronary arteries, the effect of their movement and that of the entire heart without prolonging scan time. The contrast-to-noise ratio of the IR images was on average 38% higher than that of the corresponding 4D phase. CONCLUSIONS: 4D magnetic resonance imaging is superior in that no trigger delay time needs to be determined and an additional whole-heart cine study can be obtained.     

冠状动脉MR血管成像的研究进展

随着3.0T磁共振成像在临床上的广泛应用及其成像速度和信噪比的提高,冠状动脉MR血管成像用于冠状动脉粥样硬化性心脏病的研究也更加深入。就冠状动脉MR血管成像技术、成像方法、扫描序列、临床应用以及冠状动脉粥样硬化斑块的MR成像和分子影像学研究进展进行综述。     

磁共振冠状动脉成像的研究进展

随着磁共振设备及其新技术的不断开发和进展,磁共振冠状动脉成像技术已成为显示冠状动脉形态的可靠的无创性影像检查方式。其可以精确显示冠状动脉狭窄部位并评价其血流储备情况,准确评估冠状动脉粥样硬化病变的严重程度,逐渐成为冠心病影像检查的重要方法。随着超高场磁共振设备的临床应用,当前研究主要集中于呼吸及心脏运动伪影抑制、快速数据采集等方面,以期获取高信噪比与高空间分辨力影像。     

磁共振冠状动脉成像的研究进展

随着磁共振设备及其新技术的不断开发和进展,磁共振冠状动脉成像技术已成为显示冠状动脉形态的可靠的无创性影像检查方式。其可以精确显示冠状动脉狭窄部位并评价其血流储备情况,准确评估冠状动脉粥样硬化病变的严重程度,逐渐成为冠心病影像检查的重要方法。随着超高场磁共振设备的临床应用,当前研究主要集中于呼吸及心脏运动伪影抑制、快速数据采集等方面,以期获取高信噪比与高空间分辨力影像。