Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.
Magn Reson Med. 2013 Jan;69(1):48-61. doi: 10.1002/mrm.24226. Epub 2012 Mar 5.
Phase-contrast MRI (PC-MRI) velocimetry is a noninvasive, high-resolution motion assessment tool. However, high motion sensitivity requires strong motion-encoding magnetic gradients, making phase-contrast-MRI prone to baseline shift artifacts due to the generation of eddy currents. In this study, we propose a novel nine-point balanced velocity-encoding strategy, designed to be more accurate in the presence of strong and rapidly changing gradients. The proposed method was validated using a rotating phantom, and its robustness and precision were explored and compared with established approaches through computer simulations and in vivo experiments. Computer simulations yielded a 39-57% improvement in velocity-noise ratio (corresponding to a 27-33% reduction in measurement error), depending on which method was used for comparison. Moreover, in vivo experiments confirmed this by demonstrating a 26-53% reduction in accumulated velocity error over the R-R interval. The nine-point balanced phase-contrast-MRI-encoding strategy is likely useful for settings where high spatial and temporal resolution and/or high motion sensitivity is required, such as in high-resolution rodent myocardial tissue phase mapping.
相位对比磁共振成像（PC-MRI）速度测量是一种非侵入性、高分辨率的运动评估工具。然而，高运动敏感性需要强的运动编码磁场梯度，这使得相位对比-MRI 容易由于涡流的产生而出现基线偏移伪影。在这项研究中，我们提出了一种新的九点平衡速度编码策略，旨在在存在强且快速变化的梯度时更准确。该方法使用旋转体模进行了验证，并通过计算机模拟和体内实验探索了其稳健性和精度，并与现有方法进行了比较。计算机模拟的结果表明，速度噪声比提高了 39-57%（对应于测量误差降低了 27-33%），具体取决于所使用的比较方法。此外，体内实验证实了这一点，即在 R-R 间隔内累积速度误差降低了 26-53%。九点平衡相位对比-MRI 编码策略可能适用于需要高空间和时间分辨率和/或高运动敏感性的情况，例如在高分辨率啮齿动物心肌组织相位映射中。
