验证用于胎儿心血管磁共振(CMR)的新技术是具有挑战性的,因为随机的胎儿运动妨碍了重复测量。因此,胎儿CMR发育主要是使用身体体模或产后志愿者进行的。在这项工作中,我们提出了一个开源模拟,旨在帮助开发和验证胎儿CMR的新方法.我们的方法,胎儿延长心脏-躯干心血管磁共振成像(胎儿XCMR),建立在模拟CMR采集的既定方法上,但针对胎儿心脏和身体的动态生理学进行了定制。我们提供了胎儿XCMR体模和子宫内采集的数据之间的比较,导致图像质量,解剖学,组织信号和对比。
现有的扩展心脏躯干模型被修改以创建母体和胎儿解剖结构,根据模拟运动组合,映射到CMR对比度,并转换为CMR数据。为了提供所提出的模拟和在子宫内采集的实验性胎儿CMR图像之间的比较,包括来自孕妇典型扫描的图像,并使用匹配的CMR参数生成模拟采集,运动和噪音水平。三个重建(静态、实时,和CINE),和两种运动估计方法(平移运动,胎儿心率)来自横向采集的数据,矢状,日冕,和胎儿心脏的短轴平面进行了比较,在子宫内采集,并证明了所提出的模拟框架的可行性。
总的来说,CMR对比,形态学,当将模拟与在子宫内采集的静态图像进行比较时,母体和胎儿解剖结构的相对比例由胎儿XCMR图像很好地表示。此外,在胎儿XCMR和子宫内实时图像之间,母体呼吸和胎儿心脏运动的可视化具有可比性。最后,高质量CINE图像重建为两种数据类型提供了胎儿心脏解剖和时间动态的出色描绘。
胎儿CMR体模通过模拟潜在的解剖学和生理学,为评估胎儿CMR采集和重建方法提供了一种新的方法。随着胎儿CMR领域的不断发展,新的方法将变得可用,需要仔细验证。因此,胎儿CMR体模是胎儿心脏成像持续发展的强大而方便的工具。
Validating new techniques for fetal cardiovascular magnetic resonance (CMR) is challenging due to random fetal movement that precludes repeat measurements. Consequently, fetal CMR development has been largely performed using physical phantoms or postnatal volunteers. In this work, we present an open-source simulation designed to aid in the development and validation of new approaches for fetal CMR. Our approach, fetal extended Cardiac-Torso cardiovascular magnetic resonance imaging (Fetal XCMR), builds on established methods for simulating CMR acquisitions but is tailored toward the dynamic physiology of the fetal heart and body. We present comparisons between the Fetal XCMR phantom and data acquired in utero, resulting in image quality, anatomy, tissue signals and contrast.
Existing extended Cardiac-Torso models are modified to create maternal and fetal anatomy, combined according to simulated motion, mapped to CMR contrast, and converted to CMR data. To provide a comparison between the proposed simulation and experimental fetal CMR images acquired in utero, images from a typical scan of a pregnant woman are included and simulated acquisitions were generated using matching CMR parameters, motion and noise levels. Three reconstruction (static, real-time, and CINE), and two motion estimation methods (translational motion, fetal heart rate) from data acquired in transverse, sagittal, coronal, and short-axis planes of the fetal heart were performed to compare to in utero acquisitions and demonstrate feasibility of the proposed simulation framework.
Overall, CMR contrast, morphologies, and relative proportions of the maternal and fetal anatomy are well represented by the Fetal XCMR images when comparing the simulation to static images acquired in utero. Additionally, visualization of maternal respiratory and fetal cardiac motion is comparable between Fetal XCMR and in utero real-time images. Finally, high quality CINE image reconstructions provide excellent delineation of fetal cardiac anatomy and temporal dynamics for both data types.
The fetal CMR phantom provides a new method for evaluating fetal CMR acquisition and reconstruction methods by simulating the underlying anatomy and physiology. As the field of fetal CMR continues to grow, new methods will become available and require careful validation. The fetal CMR phantom is therefore a powerful and convenient tool in the continued development of fetal cardiac imaging.