Department of Medical Physics, University of Wisconsin, Madison, Wisconsin 53705-2275, USA.
Magn Reson Med. 2010 Jun;63(6):1564-74. doi: 10.1002/mrm.22355.
Phase-contrast MRI can provide high-resolution angiographic velocity images, especially in conjunction with non-Cartesian k-space sampling. However, acquisitions can be sensitive to errors from artifacts from main magnetic field inhomogeneities and chemical shift from fat. Particularly in body imaging, fat content can cause degraded image quality, create errors in the velocity measurements, and prevent the use of self-calibrated amplitude of static field heterogeneity corrections. To reduce the influence of fat and facilitate self-calibrated amplitude of static field heterogeneity corrections, a combination of chemical shift imaging with phase-contrast velocimetry with nonlinear least-squares estimation of velocity, fat, and water signals is proposed. A chemical shift and first-moment symmetric dual-echo sequence is proposed to minimize the scan time penalty, and initial investigations are performed in phantoms and volunteers that show reduced influence from fat in velocity images.
相衬磁共振成像可以提供高分辨率的血管造影速度图像，特别是与非笛卡尔 k 空间采样结合使用时。然而，采集可能容易受到来自主磁场不均匀性和脂肪化学位移的伪影的影响。特别是在身体成像中，脂肪含量会导致图像质量下降，在速度测量中产生误差，并阻止使用自校准的静态磁场不均匀性校正幅度。为了减少脂肪的影响并促进自校准的静态磁场不均匀性校正幅度，提出了一种结合化学位移成像与相衬速度测量的方法，采用非线性最小二乘法估计速度、脂肪和水信号。提出了一种化学位移和第一矩对称双回波序列，以最小化扫描时间的惩罚，并且在体模和志愿者中进行了初步研究，结果表明速度图像中脂肪的影响降低了。
