van der Weide Remko, Viergever Max A, Bakker Chris J G
Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
Magn Reson Med. 2004 Apr;51(4):785-93. doi: 10.1002/mrm.20035.
Magnetic resonance (MR) phase-contrast (PC) flow measurements are degraded by partial volume errors when the spatial resolution is low, in particular when a large difference in signal magnitude exists between the fluid and the surrounding material. The latter is often the case in phantom studies and may be encountered when flow is measured in prosthetic vessel segments (such as shunts, grafts, and bypasses) and in contrast-enhanced blood. This paper presents a new method that is designed to measure flow in vessels of circular cross-section with Poiseuille flow and negligible background signal arising from static material around the lumen. The method calculates the average flow velocity directly from the original complex image data by integrating the signal in oppositely velocity-sensitized PC images. The radius is calculated from the summed signal modulus. The method allows accurate and resolution-insensitive measurements of the average flow velocity to be obtained in both cross-sectional and in-plane acquisitions. It is not critical to any of the assumed conditions. The validity and capabilities of the proposed technique are demonstrated by in vitro experiments.
当空间分辨率较低时，尤其是当流体与周围物质之间存在较大信号强度差异时，磁共振（MR）相位对比（PC）血流测量会受到部分容积误差的影响。在体模研究中，后一种情况经常出现，并且在测量人工血管段（如分流管、移植物和旁路）以及对比增强血液中的血流时也可能遇到。本文提出了一种新方法，该方法旨在测量具有泊肃叶流且管腔内静态物质产生的背景信号可忽略不计的圆形横截面血管中的血流。该方法通过对相反速度敏感的PC图像中的信号进行积分，直接从原始复图像数据计算平均流速。半径由信号模量总和计算得出。该方法允许在横截面和平面内采集时获得对平均流速的准确且分辨率不敏感的测量。它对任何假设条件都不关键。通过体外实验证明了所提出技术的有效性和能力。
