Accelerated Multi-Dimensional Flow Encoding by MRI

我的研究项目的主要重点是开发快速MRI方法来量化心血管生理学。这项工作的基石是相衬（PC）MRI，一个强大的非侵入性工具，用于血流测量。通常，PC MRI涉及垂直于靶血管的单个切片的处方，并且测量通过切片的流量。尽管这种方法便于测量长而直的血管中的流量，但不能很好地转换为复杂的血管几何形状或心脏。为了解决这一限制，已经开发了先进的PC MRI方法来量化3D体积上三个空间方向上的血流。这些所谓的“4D Flow”方法允许复杂血流模式的可视化，并且还可以用于量化血液动力学参数，例如壁剪切应力或压力梯度。然而，4D Flow的应用有限，因为扫描时间相对较长（>10分钟），易于因患者运动和不规则呼吸模式而产生伪影。这些挑战在儿科中加剧，因为受试者在采集期间更有可能移动，并且扫描时间变得更长（约20分钟），因为需要更高的分辨率来可视化小的心血管结构。幸运的是，1）允许快速扫描的MRI硬件进步，2）运动补偿的新技术和3）从“欠采样”数据生成高质量图像的新重建策略的融合，为大幅提高4D Flow的效率和鲁棒性提供了前所未有的机会。为了使4D Flow适用于儿科受试者，我的计划旨在开发采集和重建策略，协同结合联合收割机快速扫描，运动补偿和欠采样技术，同时确保准确的流量测量。 我的研究计划的一个长期目标是提高我们对儿科心血管生理学的理解。为了支持这一计划，要求为学员提供资金，以实现以下目标：1.批量运动检测和补偿：开创一种检测和补偿不安受试者随机运动的策略。2.无线生理运动检测：优化一种“无线”技术，用于在整个4D血流采集过程中监测心脏和呼吸运动，无需繁琐的监测设备。3.加速采集和重建：创建数据采集和重建管道，利用高度欠采样的4D Flow数据进行精确的流量测量。这些目标的实现将产生具有高空间分辨率、扫描时间低于10分钟并且不需要外部生理监测设备的稳健且高效的4D血流采集和重建方案。这一创新计划承诺推进心血管生理学发展的研究，同时为学员提供学术界或工业界职业所需的技能。

The primary focus of my research program is to develop fast MRI methods to quantify cardiovascular physiology. A cornerstone of this work is phase-contrast (PC) MRI, a powerful non-invasive tool for blood flow measurement. Typically, PC MRI involves prescription of a single slice perpendicular to a target vessel, and flow through the slice is measured. Although convenient for measuring flow in long, straight vessels, this approach does not translate well to complex vascular geometries or the heart. To address this limitation, advanced PC MRI methods have been developed to quantify blood flow in three spatial directions over a 3D volume. These so-called `4D Flow' approaches permit visualization of complex blood flow patterns, and can also be used to quantify hemodynamic parameters such as wall shear stress or pressure gradients. However, 4D Flow has seen limited adoption because scan times are relatively long (>10 minutes), making them prone to artifact from patient motion and irregular respiratory patterns. These challenges are exacerbated in pediatrics because subjects are more likely to move during acquisition, and scan times become even longer (~20 minutes) as finer resolution is necessary to visualize small cardiovascular structures. Fortunately, the convergence of 1) MRI hardware advancements that permit rapid scanning, 2) new techniques for motion compensation and 3) new reconstruction strategies which generate high quality images from "undersampled" data, provide an unprecedented opportunity to dramatically improve the efficiency and robustness of 4D Flow. With the goal of making 4D Flow applicable to pediatric subjects, my program seeks to develop acquisition and reconstruction strategies which synergistically combine rapid scanning, motion compensation, and undersampling techniques while ensuring accurate flow measurement. A long-term goal of my research program is to improve our understanding of pediatric cardiovascular physiology. To support this program, funding is requested for trainees to pursue the following Aims: 1.Bulk Motion Detection & Compensation: Pioneer a strategy to detect and compensate for the random motion of restless subjects. 2.Wireless Physiological Motion Detection: Optimize a "wireless" technique for monitoring cardiac and respiratory motion throughout the 4D flow acquisition, eliminating the need for cumbersome monitoring equipment. 3.Accelerated Acquisition & Reconstruction: Create a data acquisition and reconstruction pipeline for accurate flow measurement with highly undersampled 4D Flow data. Fulfillment of these objectives will result in a robust and efficient 4D Flow acquisition and reconstruction scheme with high spatial resolution, a scan time under 10 minutes, and no need for external physiological monitoring devices. This innovative program promises to advance research in developmental cardiovascular physiology while providing trainees with in-demand skills for careers in academia or industry.