Accelerated Multi-Dimensional Flow Encoding by MRI

我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对比（PC） MRI，一种强大的非侵入性血流测量工具。典型的，PC MRI包括一个垂直于目标血管的单片处方，并测量通过该片的流量。虽然这种方法可以方便地测量长而直的血管中的流量，但它不能很好地转化为复杂的血管几何形状或心脏。为了解决这一限制，已经开发出先进的PC MRI方法来量化三维体积上三个空间方向的血流。这些所谓的“4D流动”方法允许可视化复杂的血液流动模式，也可用于量化血液动力学参数，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分钟左右），容易受到患者运动和不规则呼吸模式的干扰。这些挑战在儿科中更加严重，因为受试者在获取过程中更有可能移动，并且扫描时间变得更长（~20分钟），因为需要更精细的分辨率来观察小的心血管结构。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，为显着提高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，将快速扫描，运动补偿和欠采样技术协同结合，同时确保准确的流量测量。我的研究计划的长期目标是提高我们对儿童心血管生理学的理解。为支持该计划，要求为学员提供资金，以实现以下目标：大块运动检测和补偿：开拓了一种检测和补偿不安分受试者随机运动的策略。2.无线生理运动检测：优化“无线”技术，在整个4D血流采集过程中监测心脏和呼吸运动，消除了对笨重的监测设备的需要。3.加速采集和重建：创建数据采集和重建管道，使用高度欠采样的4D流量数据进行精确的流量测量。实现这些目标将产生一个强大而高效的4D流量采集和重建方案，具有高空间分辨率，扫描时间低于10分钟，不需要外部生理监测设备。这一创新项目承诺推进心血管发育生理学的研究，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.