3.0T磁共振全心方法冠状动脉造影的初步评价

目的初步评价三维(3D)全心方法冠状动脉造影在3.0T磁共振应用的可行性及价值。方法采用3D分段k空间快速梯度回波序列(turbofieldecho,TFE),实时呼吸导航门控技术,心电向量(VCG)R波触发门控技术,在3.0T磁共振对12例健康志愿者进行磁共振冠状动脉造影(MRCA)检查。结果左主干和左前降支(LM LAD)、左旋支(LCX)及右冠状动脉(RCA)的血管长度(mm)分别为98±16、56±9、108±29;血管直径(mm)分别为2.6±0.4、2.4±0.3、2.6±0.3;左、右冠状动脉的信噪比(SNR)和强化噪声比(CNR)分别为35±12、19±6和23±5、18±3。结论初步研究显示全心方法MRCA在3.0T磁共振是可行的,能够显示冠状动脉的远段和管径较小的分支血管,显示了增强的信噪比。全心方法使冠状动脉定位采集过程变得简单,易操作。     

3.0T磁共振全心冠状动脉成像在诊断冠状动脉狭窄中的临床价值

目的 探讨3.0T磁共振全心冠状动脉成像在冠状动脉狭窄诊断中的临床应用价值.方法 应用3.0T MR自由呼吸三维导航快速梯度回波序列,对30例临床怀疑为冠心病患者进行MR全心冠状动脉成像检查,完成MR检查的27例中有19例进行了行冠状动脉造影检查,以血管造影为"金标准",初步估价3.0T磁共振全心冠脉成像诊断冠状动脉狭窄(>50%)的敏感性、特异性、准确度、阳性预测值及阴性预测值.结果 30例进行MR全心冠状动脉成像的患者中,27例获得了满意的检查结果(84.5%),MR全心冠状动脉成像检查在进行了冠状动脉造影检查的患者中共发现24支冠状动脉显著狭窄.与冠状动脉造影结果对照,MR全心冠状动脉成像诊断冠状动脉显著性狭窄敏感性为73.91%,特异性为82.29%,准确度为77.19%,阳性预测值为70.83%,阴性预测值为87.88%.结论 3.0T磁共振全心冠脉成像能够无创性地进行冠状动脉成像,初步评价冠状动脉主干及近、中段狭窄.冠状动脉MRA表现了较高的阴性预测值,对排除冠状动脉狭窄具有较高的临床应用价值.     

磁共振冠状动脉成像检查的护理配合

目的探讨3.0 T磁共振成像(magnetic resonance imaging,MRI)冠状动脉检查中护理配合的方法及对检查成功率的影响。方法以在我院诊治并行3.0 T超导型磁共振机在心电门控和呼吸导航自由呼吸状态下进行冠状动脉成像的26例冠心病疑似病例为对象,分析3.0 T MRI冠状动脉成像检查中护理配合的方法及对图像质量及检查成功率影响。结果22例获得满意的检查结果(84.6%);心率控制在<70次/min的患者冠状动脉图像质量较好;能有效配合呼吸训练,在均匀呼吸基础上延长呼气过程者可以提高采集效率,缩短扫描时间。3.0 TMRI全心冠状动脉成像法诊断符合率为93.11%。结论检查前给予患者相关知识的宣教及心理疏导,指导患者进行特定检查需要的呼吸训练,遵医嘱及时准确应用药物控制心率,可提高磁共振冠状动脉成像的质量。     

心率及心率变异对前瞻性心电门控64层螺旋CT冠状动脉成像图像质量的影响

目的 探讨前瞻性心电门控64层螺旋CT冠状动脉成像中心率及心率变异对图像质量的影响。方法 80名受检者接受前瞻性心电门控扫描,检查前口服美托洛尔将心率控制在65次/分以下。以4分法对各冠状动脉段的最佳图像的质量进行评定。利用Pearson相关分析法分析心率、心率变异对图像质量的影响。结果 80名受检者均顺利完成检查,共纳入分析1039段冠状动脉,其中1003段(96.54%)满足诊断需要。平均有效剂量为(6.07±1.13)mSv。右冠状动脉、左旋支及总体图像质量与心率呈负相关(P＜0.05),左前降支、左主干图像质量与心率无显著相关性。总体及各支冠状动脉图像质量与心率变异无显著相关性。结论 前瞻性心电门控64层螺旋CT冠状动脉成像能够降低辐射剂量,当受检者心率控制在65次/分以下时,心率变异对图像质量无显著影响,但心率仍是影响图像质量的因素之一。     

3.0T无对比剂MR冠状动脉造影图像质量的影响因素

目的 分析影响3.0T无对比剂MR冠状动脉造影（MRCA）图像质量的因素。方法 前瞻性对170例疑诊冠状动脉疾病患者行3.0T全心无对比剂MRCA检查，针对冠状动脉主要分支包括左前降支（LAD）、左回旋支（LCX）及右冠状动脉（RCA）进行主观评分，计算其信噪比（SNR）；根据3支总得分将图像分为优、良、中或差；采用单因素分析及有序logistic回归分析筛选MRCA图像质量的影响因素。观察回归分析结果显示差异有统计学意义的参数与MRCA图像质量的相关性，并以受试者工作特征（ROC）曲线分析其评估图像质量的效能。结果 MRCA主观评分结果为优、良、中（以上可用于诊断）及差者（不可用于诊断）分别为36、46、57及31例；其间LAD、LCX及RCA的SNR总体差异具有统计学意义（P均<0.01）。患者体质量指数（BMI）（OR=0.64）、心率（OR=0.96），以及采集效率（OR=1.06）和体位（OR=0.33）均为MRCA图像质量的影响因素（P均<0.05），且均与图像质量评分相关（r=－0.604、－0.250、0.500、0.407，P均<0.001）；分别以≤25.5 kg/m²、≤70次/分、≥37%及手下摆为阈值，BMI、心率、采集效率及手上举或下摆判断MRCA图像可否用于诊断的曲线下面积（AUC）为0.802、0.704、0.955及0.686。结论 患者BMI、心率，以及采集效率和体位为3.0T无对比剂MRCA图像质量的影响因素。     

屏气法三维磁共振冠状动脉血管造影诊断先天性冠状动脉起源畸形

目的探讨屏气法三维磁共振冠状动脉造影(3D MRCA)显示畸形冠状动脉与主动脉根部、右心室流出道关系的可行性及价值.方法 5名临床拟诊患者、1例志愿者接受MRCA检查,以屏气法三维稳态进动快速成像(3D true-FISP)梯度回波序列采集图像,获得左、右冠状动脉图像,分析畸形冠状动脉近段与冠状动脉窦(Valsalva窦)、右心室流出道的位置关系.结果 6例MRCA均明确诊断先天性冠状动脉起源畸形,畸形血管近段均走行于主动脉根部与右心室流出道之间.结论屏气法3D MRCA可明确诊断先天性冠状动脉起源畸形,显示畸形冠状动脉近段的走行路经,是一种可行的影像诊断方法.     

MR冠脉成像靶容积与全心扫描方法的优势探讨

目的探讨自由呼吸导航三维采样磁共振冠脉成像靶容积和全心扫描方法的特点与优势。方法对21例志愿者进行1.5T自由呼吸磁共振冠脉成像扫描,包括右冠状动脉和左旋支的靶容积及全心扫描,两种方法的基本扫描参数相同,扫描完成进行后处理,得到靶容积和全心扫描的右冠状动脉及左旋支图像,对右冠脉及左旋支各节段的图像质量进行评分,测量右冠脉及左旋支的长度,观察右冠脉后降支的显示情况,评价两种方法的特点和优势。结果全心扫描的时间明显长于单次冠脉靶容积扫描的时间,两种方法在显示右冠状动脉和左冠脉旋支的长度上无明显差别,对于右冠状动脉后降支的显示而言,全心扫描较靶容积扫描具有明显的优势,在图像质量方面,靶容积扫描优于全心扫描方法。结论自由呼吸导航三维采样磁共振冠脉成像靶容积和全心扫描方法具有各自的优势,在临床中可根据具体情况进行选择应用或联合应用。     

全心冠状动脉MR成像的图像质量及其影响因素

目的评价全心冠状动脉MR成像(WH CMRA)的图像质量及其影响因素。方法对88例疑诊冠心病者,采用1.5T非对比增强、心电门控兼呼吸导航、T2预备脉冲并脂肪抑制的3D稳态自由进动序列扫描;采用4分制(1分,差;4分,优)评价图像质量,对得分2～4分者评估冠状动脉的狭窄程度,以CAG显示狭窄≥50%为标准评价MR的准确率。结果①完成组:79例(79/88,89.77%)完成WH CMRA检查,扫描时间(13.28±4.33)min,心率(67±8)次/分,呼吸导航效率(34.12±8.10)%,体质量指数(BMI)为(25.90±3.20)kg/m2;75例平均图像质量评分(2.9±1.0)分,4例图像质量为1分;②对照组:42例(42/75,56.00%)完成CAG检查,扫描时间(13.50±4.60)min,心率(67±10)次/分,图像质量评分(3.2±0.9)分,与CAG间隔(5±2)天;WH CMRA诊断冠状动脉狭窄的敏感度、特异度、阳性预测值、阴性预测值和准确率分别为90.48%(19/21)、66.67%(14/21)、73.08%(19/26)、87.50%(14/16)和78.57%(33/42);③完成组与对照组间平均年龄、心率、扫描时间、呼吸导航效率、BMI和图像质量间差异均无统计学意义(P均>0.05)。结论WHCMRA图像质量大多能满足诊断需要,主要影响因素包括心脏搏动、呼吸运动和BMI。     

双源CT非心率控制自适应前瞻性心电门控序列扫描冠状动脉成像

目的探讨双源CT非心率控制低剂量自适应前瞻性心电门控序列扫描冠状动脉成像的可行性。方法前瞻性收集94例患者进行双源CT非心率控制自适应前瞻性心电门控序列扫描技术冠状动脉成像。由2名放射科医师利用双盲法以5分法评定系统对冠状动脉15支分支血管的成像质量,图像质量≥3分认为可满足影像学评价要求;分析平均心率、心率变化与图像质量的相关性,评估2名医师评价图像质量的一致性,并计算容积CT剂量指数(CTDIvol)和有效剂量(ED)。结果扫描期间94例患者的平均心率为(87.24±13.76)次/分。共1410段冠状动脉节段纳入分析,其中1334段(94.61%)可满足影像学评价要求,76段(5.39%)不能满足要求。94例患者平均冠状动脉得分为(4.25±0.93)分,图像质量与心率(r=-0.17,P=0.11)及心率变化(r=0.10,P=0.32)均无相关性,2名评价者间的一致性较好(Kappa值=0.90,P<0.001),CTDIvol均值为(11.84±1.76)mGy,平均ED为(2.19±0.45)mSv。结论双源CT自适应前瞻性心电门控序列扫描冠状动脉成像技术可无需控制心率而得到能够满足临床诊断需要的冠状动脉图像,且能显著降低辐射剂量。     

呼吸运动适应参数对磁共振冠状动脉成像质量的影响

目的 探讨在全心对比增强磁共振冠状动脉成像中,呼吸运动适应(resp move.adap)参数的使用与否对呼吸平稳患者成像质量的影响。 方法 应用3.0T磁共振扫描仪对34名志愿者进行全心对比增强检查,其中26名志愿者成功完成检查。应用序贯抽样方案分为A和B两组,每组13名志愿者。A组使用参数resp move.adap,B组不使用该参数。应用两样本U检验及χ²检验对比分析两种方法的成像质量及段落显示率。 结果 两组图像质量比较差异有统计学意义(U=46.00,P=0.034),右冠状动脉节段显示率差异有统计学意义(χ²=6.385,P=0.012),前降支节段显示率差异有统计学意义(χ²=5.764,P=0.016),回旋支节段显示率差异无统计学意义(χ²=2.229,P=0.135)。组间性别及年龄差异无统计学意义。 结论 在对比增强全心磁共振冠状动脉成像中,对于呼吸平稳的患者,不使用resp move.adap参数成像的效果优于使用该参数。     

A study of in vitro and in vivo MR of free-breathing whole-heart 3D coronary angiography using parallel imaging

To evaluate parallel-imaging methods in free-breathing whole-heart 3D coronary magnetic resonance angiography and assess the navigator techniques and visualization rates of the major coronary arteries. We compared key parameters of the generalized autocalibrating partially parallel acquisition and modified sensitive encoding images in vitro phantom MRI; performed the MRA with GRAPPA parallel imaging in healthy volunteers; compared 1D- and 2D-prospective acquisition correction and analyzed the differences; and evaluated the visualization of major coronary arterial branches. GRAPPA images had higher signal-to-noise ratio and contrast-to-noise ratio and fewer aliasing artifacts. The coronary arteries were adequately visualized in 38 volunteers. 2D-PACE had a higher navigator efficiency, shorter scan time, and gave clearer reconstructed images in comparison with 1D-PACE. GRAPPA images were superior to mSENSE images. Whole-heart 3D coronary MRA along with parallel-imaging technique is a potential clinical method, and 2D-PACE is a better navigation technique than 1D-PACE.     

A study of in vitro and in vivo MR of free-breathing whole-heart 3D coronary angiography using parallel imaging

To evaluate parallel-imaging methods in free-breathing whole-heart 3D coronary magnetic resonance angiography and assess the navigator techniques and visualization rates of the major coronary arteries. We compared key parameters of the generalized autocalibrating partially parallel acquisition and modified sensitive encoding images in vitro phantom MRI; performed the MRA with GRAPPA parallel imaging in healthy volunteers; compared 1D- and 2D-prospective acquisition correction and analyzed the differences; and evaluated the visualization of major coronary arterial branches. GRAPPA images had higher signal-to-noise ratio and contrast-to-noise ratio and fewer aliasing artifacts. The coronary arteries were adequately visualized in 38 volunteers. 2D-PACE had a higher navigator efficiency, shorter scan time, and gave clearer reconstructed images in comparison with 1D-PACE. GRAPPA images were superior to mSENSE images. Whole-heart 3D coronary MRA along with parallel-imaging technique is a potential clinical method, and 2D-PACE is a better navigation technique than 1D-PACE.     

Noninvasive test of nitrate-induced coronary vasomotion by 1.5-T whole-heart 3D magnetic resonance angiography using a T2-prepared SSFP sequence

This study was aimed to investigate the use of 1.5-T whole-heart 3D coronary MRA employing a T2-prepared SSFP sequence for assessing epicardial coronary artery vasodilation following exogenous nitrates. Navigator-gated whole-heart 3D coronary MRA was performed before and after sublingual nitroglycerin (NTG) in 22 volunteers and a T2-prepared SSFP sequence was used for imaging of coronary arteries without MR contrast agent. Coronary cross-sectional area was measured on pre- and post-NTG images of equivalent coronary segments in the major coronary arteries and whole-heart coronary vasodilation was analyzed quantitatively. Measurements were obtained by two independent investigators. Coronary vasodilation could be observed directly on multiplanar reformatted and three-dimensional volume-rendered MR images. On quantitative analysis, NTG administration results in the whole-heart coronary vasodilation by an average of 37.3?±?12.7%. There was moderate yet significant correlation between the NTG-induced vasodilation and age (r?=?-0.52, P?=?0.02). The mean absolute cross-sectional area of the coronary arteries was significantly higher after sublingual NTG in all the major coronary arteries. The coronary area measurements had an interobserver variability of 8?±?3% and an intraoberver variability of 4?±?2%. Non-contrast-enhanced 1.5-T SSFP whole-heart coronary MRA can noninvasively measure endothelium-independent coronary vasodilation over the entire heart with high feasibility and is a promising noninvasive method to explore whole-heart coronary smooth muscle cell function following exogenous nitrates in clinical practice.     

Magnetic resonance imaging of coronary artery occlusions in the navigator technique

Non-invasive assessment of coronary arteries is possible with magnetic resonance imaging (MRI). Respiratory gated MR coronary angiography is a new imaging technique that permits reconstruction of the coronary arteries based on a three-dimensional (3D) data set obtained from the free-breathing patient. In this study, respiratory gated MR angiography (MRA) was performed to assess coronary artery occlusions. MRI was performed in 25 patients who had been referred for conventional coronary angiography because of suspected coronary artery disease. Coronary artery occlusion was evaluated in the proximal and middle vessel segments after multiplanar coronary reconstruction of the MR images. Five patients were excluded from the study; in the remaining 20 patients 120 coronary artery segments were analyzed. Good image quality could be obtained for 85% of the segments. Eighteen of the 24 occlusions were confirmed by MRI, the overall sensitivity was 75% and the specificity was 100%. The best results were found in the proximal left anterior descending (LAD) and descending parts of the right coronary artery (RCA), where all occlusions were confirmed. These results showed that coronary artery occlusions can be detected in the proximal and middle LAD and RCA using 3D respiratory gated MRA. Further technical improvements, especially in spatial resolution, are necessary before MRA can become a reliable diagnostic tool in the non-invasive evaluation of coronary arteries.     

3D全心冠状动脉MRI技术

近十年来,三维冠状动脉成像技术的图像信躁比和空间分辨率明显提高,为冠状动脉的无创检查提供了一种安全可靠的手段.西门子公司在1.5和3.0 T系统上都提供了靶容积与全心扫描的冠状动脉成像序列,作者主要针对全心冠状动脉成像的技术进行介绍.     

Coronary artery magnetic resonance angiography (MRA): a comparison between the whole-heart and volume-targeted methods using a T2-prepared SSFP sequence.

In this study, coronary MRA was performed on 10 healthy volunteers using the whole-heart and volume-targeted scans with comparable imaging parameters. Similar results in the SNR, CNR, and vessel diameter were observed. The depicted length of coronary arteries was longer using the whole-heart scan (whole-heart: RCA/LAD = 13.4 +/- 3.9/10.5 +/- 1.6 cm; volume-targeted: RCA/LAD = 11.0 +/- 2.6/8.7 +/- 1.8 cm). Imaging times for the RCA- (3.8 +/- 1.4 minutes) and LAD-targeted (3.6 +/- 1.3 minutes) are similar, while the time required for one whole-heart scan is significantly longer (12.2 +/- 4.0 minutes). The measured vessel sharpness was higher using the volume-targeted method (whole-heart: RCA/LAD = 0.65 +/- 0.18/0.78 +/- 0.16; volume-targeted: RCA/LAD = 0.84 +/- 0.22/0.90 +/- 0.20). Combination of the whole-heart and volume-targeted methods could be potentially useful in clinical applications of coronary MRA.     

Effects of respiratory motion on coronary wall MR imaging: a quantitative study of older adults

The aim of the present study is to assess the effects of respiratory motion on the image quality of two-dimensional (2D), free-breathing, black-blood coronary wall magnetic resonance (MR) imaging. This study was compliance with the HIPPA. With the approval of the institution review board, 230 asymptomatic participants, including 164 male patients (72.9 ± 4.4 years) and 66 female patients (72.4 ± 5.1 years), were recruited. Written informed consent was obtained. A 2D navigator (NAV)-gated, black-blood coronary wall MR imaging sequence was run on the left main artery, the left anterior descending artery and the right coronary artery. The drift of the location of the NAV and scan efficiency were compared between good (scored 2 or 3) and poor images (scored 1). Age, body weight, body weight index, heart rate, length of the rest period of cardiac motion, diaphragm excursion and breathing frequency were compared using a t test between the “successful” (having 2 or 3 good images) and “unsuccessful” cases (having 1 or 0 good images). A logistic regression model was applied to identify the contributors to good image quality. The drift of the NAV location and the scan efficiency were higher in the 411 good images compared with the 279 poor images. Minimal drift of the NAV location and low body weight were identified as independent predictors of good images after using a logistic regression model to adjust for multiple physiological and technical factors. The stability of respiratory motion significantly influences the image quality of 2D, free-breathing, black-blood coronary wall MR imaging.     

Fusion of CT coronary angiography and whole-heart dynamic 3D cardiac MR perfusion: building a framework for comprehensive cardiac imaging

The purpose of this work was to develop a framework for 3D fusion of CT coronary angiography (CTCA) and whole-heart dynamic 3D cardiac magnetic resonance perfusion (3D-CMR-Perf) image data—correlating coronary artery stenoses to stress-induced myocardial perfusion deficits for the assessment of coronary artery disease (CAD). Twenty-three patients who underwent CTCA and 3D-CMR-Perf for various indications were included retrospectively. For CTCA, image quality and coronary diameter stenoses >?50% were documented. For 3D-CMR-Perf, image quality and stress-induced perfusion deficits were noted. A software framework was developed to allow for 3D image fusion of both datasets. Computation steps included: (1) fully automated segmentation of coronary arteries and heart contours from CT; (2) manual segmentation of the left ventricle in 3D-CMR-Perf images; (3) semi-automatic co-registration of CT/CMR datasets; (4) projection of the 3D-CMR-Perf values on the CT left ventricle. 3D fusion analysis was compared to separate inspection of CTCA and 3D-CMR-Perf data. CT and CMR scans resulted in an image quality being rated as good to excellent (mean scores 3.5?±?0.5 and 3.7?±?0.4, respectively, scale 1–4). 3D-fusion was feasible in all 23 patients, and perfusion deficits could be correlated to culprit coronary lesions in all but one case (22/23?=?96%). Compared to separate analysis of CT and CMR data, coronary supply territories of 3D-CMR-Perf perfusion deficits were refined in two cases (2/23?=?9%), and the relevance of stenoses in CTCA was re-judged in four cases (4/23?=?17%). In conclusion, 3D fusion of CTCA/3D-CMR-Perf facilitates anatomic correlation of coronary lesions and stress-induced myocardial perfusion deficits thereby helping to refine diagnostic assessment of CAD.     

3D MR coronary angiography: optimization of the technique and preliminary results

Objective: Current clinical full MR angiography with multiple breathhold multiple thin slab acquisition (MTS) is difficult and arduous. This study describes the optimisation of the whole heart free – breathing balanced turbo field echo (B-TFE) protocol. A high-resolution image of the whole heart is produced in less or comparable time to MTS acquisition and allows for reconstruction afterwards to visualise the individual coronary arteries. The scan is easily performed because the volume has to be targeted only once.Design and setting: Eighteen healthy adults without a history of cardiovascular disease underwent free-breathing 3D MR angiography with the B-TFE protocol. The whole-heart data set was reformatted in identical orientations in all subjects to visualise the major coronary arteries.Main outcome measures: Vessel length, signal and contrast to noise ratio were determined and compared for each vessel.Results: Mean visible vessel lengths were 116 mm for the right, 102 mm for the left main and left descending and 76 mm for the left circumflex coronary artery. The average signal to noise ratio was 7.5 and contrast to noise ratio was 4.9. Because of the need for synchronised cardiac and respiratory triggering the coronaries could not be judged in 25% of the subjects.Conclusions: The optimised B-TFE protocol had equal judgeability and vessels could be judged over longer contiguous distances compared to earlier implementations of the B-TFE protocol. We conclude whole heart free breathing navigator-gated and slice-tracked 3D coronary MR angiography with use of the adjusted B-TFE protocol is possible, but still suboptimal for clinical use.