Name: human fetal blood flow quantification with magnetic resonance imaging and motion compensation
Uploaded: 2021-01-07T13:00:00
Description: Watch this Scientific Journal Video about Human Fetal Blood Flow Quantification with Magnetic Resonance Imaging and Motion Compensation at JoVE.com

所有MRI扫描都是在志愿者的知情同意下进行的，这是我们机构研究伦理委员会批准的一项研究的一部分。
注意：下面描述的方法已用于3T MRI系统。采集使用径向相衬MRI序列进行。该序列是通过修改制造商的笛卡尔相衬MRI的读出轨迹（以实现星状模式）来制备的。序列和样品实验方案可应要求通过我们的C2P交换平台获得。这项工作中的所有重建都是在具有以下规格的标...

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该方法能够无创地测量人类胎儿大血管中的血流量，并允许通过使用迭代重建技术进行回顾性运动校正和心脏门控。过去曾使用MRI进行胎儿血流定量1，3，8，9。这些研究具有减轻运动损坏的前瞻性方法，如果从扫描仪上的初始重建中直观地识别出胎儿粗大运动，则将重复扫描...

对胎儿循环进行全面评估对于监测胎儿病变（如胎儿生长受限 （FGR） 和先天性心脏病 （CHD））是必要的1，2，3。在子宫内，患者管理和产后护理计划取决于胎儿病理的严重程度4，5，6，7。最近证明了使用MRI定量胎儿血流的可行性及其在评估胎儿病理学中的应用3，8，9。然而，成像方法面临着挑战，例如增加成像时间以实现高时空分辨率，缺乏心脏同步方法以及不可预测的胎儿运动10。
胎儿脉管系统由小结构组成（包括降主动脉、动脉导管、升主动脉、主动脉、主肺动脉和上腔静脉的主要血管直径 ~5 mm）11，12，13）。为了解析这些结构并量化流量，需要高空间分辨率的成像。此外，胎儿的心率大约是成人的两倍。因此，还需要高时间分辨率来解析整个胎儿心动周期的动态心脏运动和血流。在这种高时空分辨率下进行传统成像需要相对较长的采集时间。为了解决这个问题，引入了加速胎儿MRI14，15，16。简而言之，这些加速技术涉及数据采集期间频域欠采样和使用迭代技术的回顾性高保真重建。其中一种方法是压缩感知（CS）重建，当重建的图像在已知域中稀疏并且欠采样伪影不相干时，它允许从严重欠采样的数据中重建图像17。
胎儿成像中的运动是一项重大挑战。运动不良可能由母亲的呼吸运动、母亲的大量运动或胎儿的粗大运动引起。母体呼吸导致胎儿的周期性翻译，而胎动则更为复杂。胎动可分为局部或粗大10，18。局部运动仅涉及身体部分的运动。它们通常持续约10-14秒，并且其频率随着妊娠而增加（足月时每小时~90次）10。这些移动通常会导致小的损坏，并且不会影响感兴趣的成像区域。然而，胎儿的剧烈运动会导致通过平面运动组件的严重图像损坏。这些运动是由脊柱介导的全身运动，持续60-90秒。
为避免胎动造成的伪影，首先采取措施尽量减少母体运动。孕妇在扫描仪床上使用支撑枕头并穿着舒适的长袍，并可能让她们的伴侣在扫描仪旁边以减少幽闭恐惧症19，20。为了减轻母亲呼吸运动的影响，研究在母亲屏气的情况下进行了胎儿MR检查21，22，23。然而，鉴于怀孕受试者的屏气耐受性降低，这种获取必须很短（~15 s）。最近，针对胎儿MRI引入了回顾性运动矫正方法14，15，16。这些方法使用注册工具包跟踪胎儿运动，并纠正运动或丢弃采集数据的不可纠正部分。
最后，通常使用心电图（ECG）门控获取产后心脏MR图像，以使数据采集与心动周期同步。在没有门控的情况下，整个心动周期的心脏运动和脉动流结合在一起，产生伪影。不幸的是，胎儿心电信号受到母体心电信号24的干扰和磁场25的失真。因此，已经提出了胎儿心脏门控的替代非侵入性方法，包括自门控，度量优化门控（MOG）和多普勒超声门控21，26，27，28。
如以下各节所述，我们量化胎儿血流量的MRI方法利用了我们实验室开发的新型门控方法MOG，并结合了加速MRI采集的运动校正和迭代重建。该方法基于先前发表的研究14中的管道，由以下五个阶段组成：（1）胎儿血流采集，（2）实时重建，（3）运动校正，（4）心脏门控和（5）门控重建。

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>elastix</td>
			<td>Image Sciences Institute, University Medical Center Utrecht</td>
			<td></td>
			<td>Image registration software</td>
		</tr>
		<tr>
			<td>Geforce GTX 960&#160;</td>
			<td>Nvidia&#160;</td>
			<td>04G-P4-3967-KR</td>
			<td></td>
		</tr>
		<tr>
			<td>gpuNUFFT</td>
			<td>CAI&#178;R</td>
			<td></td>
			<td>Non-uniform fast Fourier transform</td>
		</tr>
		<tr>
			<td>MAGNETOM Prisma</td>
			<td>Siemens</td>
			<td>10849583</td>
			<td></td>
		</tr>
		<tr>
			<td>MATLAB</td>
			<td>MathWorks</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Radial Phase Contrast MRI sequence</td>
			<td></td>
			<td></td>
			<td>Trajectory modification of manufacturer&#39;s Cartesian Phase Contrast sequence</td>
		</tr>
		<tr>
			<td>Segment</td>
			<td>Medvisio</td>
			<td></td>
			<td>Data analysis</td>
		</tr>
		<tr>
			<td>VENGEANCE</td>
			<td>Corsair</td>
			<td>LPX DDR4-2666&#160;</td>
			<td></td>
		</tr>
	</tbody>
</table>

human fetal blood flow quantification with magnetic resonance imaging and motion compensation

磁共振成像（MRI）是临床评估心血管形态和心脏功能的重要工具。它也是基于相差MRI的血流量化的公认护理标准。虽然这种血流测量在成人中已经存在了几十年，但将这种能力扩展到胎儿血流的方法直到最近才被开发出来。
主要血管中的胎儿血流定量对于监测先天性心脏病 （CHD） 和胎儿生长受限 （FGR） 等胎儿病理非常重要。冠心病引起心脏结构和脉管系统的改变，从而改变胎儿的血液过程。在FGR中，通过扩张分流器改变血流路径，从而增加大脑的含氧血液供应。血流定量可以评估胎儿病理的严重程度，这反过来又允许适合子宫内的患者管理和产后护理计划。
将相差MRI应用于人类胎儿的主要挑战包括血管体积小，胎心率高，由于母亲呼吸而导致的潜在MRI数据损坏，不可预测的胎儿运动以及缺乏传统的心脏门控方法来同步数据采集。在这里，我们描述了我们实验室的最新技术发展，这些技术发展能够使用相差MRI量化胎儿血流，包括加速成像，运动补偿和心脏门控方面的进展。

一般来说，血流MRI相检查针对六大胎儿血管：降主动脉、升主动脉、主肺动脉、动脉导管、上腔静脉和脐静脉。临床医生对这些血管感兴趣，因为它们通常与冠心病和FGR有关，影响整个胎儿的血液分布9。径向相衬MRI的典型扫描持续时间为每血管17秒，因此扫描时间短，同时也为CINE重建提供了足够的数据采集时间。代表性结果的总采集时间，包括定位器和相衬MRI，为3 min。在这项?...

Watch this Scientific Journal Video about Human Fetal Blood Flow Quantification with Magnetic Resonance Imaging and Motion Compensation at JoVE.com

Human Fetal Blood Flow Quantification with Magnetic Resonance Imaging and Motion Compensation

在这里，我们提出了一种用MRI快速测量胎儿血流的协议，并回顾性地进行运动矫正和心脏门控。

通过磁共振成像和运动补偿进行人胎儿血流定量

Magnetic resonance imaging (MRI) is an important tool for the clinical assessment of cardiovascular morphology and heart function. It is also the ...

胎儿MRI面临几个挑战。该协议解决了胎儿运动，高空间和时间分辨率要求以及缺乏外部门控方法的问题。该技术通过压缩传感利用加速成像，从而减少成像时间，回顾性地校正胎儿运动，并允许使用指标优化的门控提取胎儿心率。目前，该技术仅用于研究，但它具有监测和治疗胎儿病理的潜力，例如先天性心脏病和宫内生长受限。在MRI台上协助母亲处于适当的舒适位置后，设置仪器进行定位器检查，以0.9 x 0.9 x 10立方厘米的分辨率，5毫秒的回声时间，15毫秒的重复时间，450 x 450平方毫米的视野和六个切片。设置运行精细定位器检查的参数，以定位胎儿脉管系统，切片组以胎儿心脏为中心，分辨率为 1.1 x 1.1 x 6 立方毫米，回波时间为 2.69 毫秒，重复时间为 1335.4 毫秒，视野为 350 x 350 平方毫米，10 个切片和轴向到胎儿的方向。然后用矢状面和冠状方向重复精细的定位器，以获得更清晰的胎儿血管视图。为了测量胎儿血流量，在定位胎儿血管后识别感兴趣的血管。例如，降主动脉是矢状平原脊柱附近的长直血管，升主动脉和主肺动脉可分别识别为离开左心室和右心室的血管。动脉导管可作为降主动脉近端的主肺动脉的下游段进行追踪。上腔静脉可以从靠近胎儿心脏底部的轴向平原识别为与升主动脉相邻的血管。规定一个垂直于感兴趣胎儿血管轴线的切片，并在MRI控制台上旋转和移动切片指南，使切片垂直于目标血管相交。将扫描参数设置为径向相衬MRI采集，1.3 x 1.3 x 5立方毫米分辨率，3.25毫秒的回波时间，5.75毫秒的分辨率时间，240 x 240平方毫米的视场，一层，每秒100至150厘米的速度和涂层，具体取决于感兴趣的容器， 通过飞机，无线电查看速度和涂层方向，以及每端1500代码自由呼吸。运行扫描后，根据执行并在MRI控制台上显示的初始平均重建时间验证处方。对每个目标血管重复此操作，如果目标血管不存在或可识别。在重建胎儿流CINEs之后，将重建的数据文件加载到适当的血流分析软件程序中，并在解剖学和速度敏感图像中绘制包含感兴趣血管腔的感兴趣区域。将感兴趣的区域传播到所有心相，并纠正血管直径的变化。然后记录每个感兴趣区域内的流量测量值。在此代表性分析中，提取的胎儿一号和胎儿二号的运动参数描述了扫描期间降主动脉的运动。在这里，可以观察到每个实时时间框架与胎儿一和胎儿二的所有其他共同注册帧的共享互信息。用于获取心脏门控信息的第二次实时重建每个切片需要10分钟，并且胎儿心跳间隔是通过使用多参数模型的度量优化门控得出的，如图所示。最终的电影重建。使用回顾性运动校正和门控数据，每个切片需要三分钟，并允许在收缩期峰值生成胎儿的解剖学和速度重建。带有运动校正的重建显示船只具有更锋利的壁。如果没有运动校正，降主动脉会更模糊，更不明显。每个胎儿测量的流量曲线显示，在没有运动矫正的情况下，重建中的峰值和平均流量高于运动矫正的胎儿。该技术正被用于研究胎儿病理学中的血液分布。这种方法的扩展允许多维胎流可视化和测量。

Research

JoVE Journal

Medicine

Magnetic Resonance Derived Myocardial Strain Assessment Using Feature Tracking

磁共振衍生的心肌劳损评估使用特征跟踪

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that ...

科研

医学

Magnetic Resonance Imaging Quantification of Pulmonary Perfusion using Calibrated Arterial Spin Labeling

使用校准动脉自旋标记磁共振肺灌注显像定量

This demonstrates a MR imaging method to measure the spatial distribution of pulmonary blood flow in healthy subjects 
during normoxia (inspired O2, ...

Isolation, Culture, and Imaging of Human Fetal Pancreatic Cell Clusters

分离，培养和成像胎儿胰腺细胞集群

For almost 30 years, scientists have demonstrated that human fetal ICCs transplanted under the kidney capsule of nude mice matured into functioning ...

Tracking the Mammary Architectural Features and Detecting Breast Cancer with Magnetic Resonance Diffusion Tensor Imaging

跟踪乳腺建筑特色与检测乳腺癌的磁共振扩散张量成像

Breast cancer is the most common cause of cancer among women worldwide. Early detection of breast cancer has a critical role in improving the quality of ...

Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease

骨骼肌疾病的定量磁共振成像

Quantitative magnetic resonance imaging (qMRI) describes the development and use of MRI to quantify physical, chemical, and/or biological properties of ...

Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia

同时PET / MRI成像在小鼠脑缺氧缺血

Dynamic changes in tissue water diffusion and glucose metabolism occur during and after hypoxia in cerebral hypoxia-ischemia reflecting a bioenergetics ...

Cardiac Magnetic Resonance Imaging at 7 Tesla

7号特斯拉的心脏磁共振成像

CMR at an ultra-high field (magnetic field strength B0&#160;&#8805; 7 Tesla) benefits from the signal-to-noise ratio (SNR) advantage inherent at higher ...

Phase Contrast Magnetic Resonance Imaging in the Rat Common Carotid Artery

大鼠颈总动脉的相位对比磁共振成像

Phase contrast magnetic resonance imaging (PC-MRI) is a noninvasive approach that can quantify flow-related parameters such as blood flow. Previous ...

Quantification of Levator Ani Hiatus Enlargement by Magnetic Resonance Imaging in Males and Females with Pelvic Organ Prolapse

男性和女性盆腔器官脱垂的磁共振成像对左旋的定量研究

Here we present a protocol to examine the levator ani hiatus in males and females with pelvic organ prolapse, during the Valsalva maneuver and while ...

Cardiac Magnetic Resonance for the Evaluation of Suspected Cardiac Thrombus: Conventional and Emerging Techniques

心脏磁共振评估疑似心脏血栓:常规和新兴技术

We present the conventional cardiac magnetic resonance (CMR) protocol for evaluating a suspected thrombus and highlight emerging techniques.&#160;The ...