Töger Johannes, Zahr Matthew J, Aristokleous Nicolas, Markenroth Bloch Karin, Carlsson Marcus, Persson Per-Olof
Department of Clinical Sciences Lund, Diagnostic Radiology, Lund University, Skåne University Hospital, Lund, Sweden.
Department of Clinical Sciences Lund, Clinical Physiology, Lund University, Skåne University Hospital, Lund, Sweden.
Magn Reson Med. 2020 Oct;84(4):2231-2245. doi: 10.1002/mrm.28269. Epub 2020 Apr 8.
Three-dimensional, time-resolved blood flow measurement (4D-flow) is a powerful research and clinical tool, but improved resolution and scan times are needed. Therefore, this study aims to (1) present a postprocessing framework for optimization-driven simulation-based flow imaging, called 4D-flow High-resolution Imaging with a priori Knowledge Incorporating the Navier-Stokes equations and the discontinuous Galerkin method (4D-flow HIKING), (2) investigate the framework in synthetic tests, (3) perform phantom validation using laser particle imaging velocimetry, and (4) demonstrate the use of the framework in vivo.
An optimizing computational fluid dynamics solver including adjoint-based optimization was developed to fit computational fluid dynamics solutions to 4D-flow data. Synthetic tests were performed in 2D, and phantom validation was performed with pulsatile flow. Reference velocity data were acquired using particle imaging velocimetry, and 4D-flow data were acquired at 1.5 T. In vivo testing was performed on intracranial arteries in a healthy volunteer at 7 T, with 2D flow as the reference.
Synthetic tests showed low error (0.4%-0.7%). Phantom validation showed improved agreement with laser particle imaging velocimetry compared with input 4D-flow in the horizontal (mean -0.05 vs -1.11 cm/s, P < .001; SD 1.86 vs 4.26 cm/s, P < .001) and vertical directions (mean 0.05 vs -0.04 cm/s, P = .29; SD 1.36 vs 3.95 cm/s, P < .001). In vivo data show a reduction in flow rate error from 14% to 3.5%.
Phantom and in vivo results from 4D-flow HIKING show promise for future applications with higher resolution, shorter scan times, and accurate quantification of physiological parameters.
三维时间分辨血流测量（4D 血流）是一种强大的研究和临床工具，但仍需要提高分辨率和缩短扫描时间。因此，本研究旨在：（1）提出一种用于基于优化驱动的模拟血流成像的后处理框架，称为结合纳维 - 斯托克斯方程和间断伽辽金方法的具有先验知识的 4D 血流高分辨率成像（4D-flow HIKING）；（2）在模拟测试中研究该框架；（3）使用激光粒子成像测速技术进行体模验证；（4）展示该框架在体内的应用。
开发了一种包括基于伴随优化的计算流体动力学求解器来使计算流体动力学解决方案与 4D 血流数据相匹配。进行了二维模拟测试，并对脉动流进行了体模验证。使用粒子成像测速技术获取参考速度数据，并于 1.5 T 下采集 4D 血流数据（此处原文未明确说明采集 4D 血流数据的设备，推测可能是在 1.5 T 的磁共振设备上采集）。在 7 T 下对一名健康志愿者颅内动脉进行体内测试，以二维血流作为参考（此处原文未明确说明采集二维血流数据的设备，推测可能是在 7 T 的磁共振设备上采集）（此处推测是根据前文 4D-flow 数据采集设备推测二维血流数据采集可能也是在相应磁共振设备上进行）。
模拟测试显示误差较低（0.4% - 0.7%）。与输入的 4D 血流相比，体模验证表明在水平方向（平均 -0.05 对 -1.11 cm/s，P <.001；标准差 1.86 对 4.
