Brain Imaging and Analysis Center, Duke University, Durham, North Carolina 27705, United States of America.
Magn Reson Med. 2012 Oct;68(4):1255-61. doi: 10.1002/mrm.24124. Epub 2011 Dec 28.
Multishot spiral imaging is a promising alternative to echo-planar imaging for high-resolution diffusion-weighted imaging and diffusion tensor imaging. However, subject motion in the presence of diffusion-weighting gradients causes phase inconsistencies among different shots, resulting in signal loss and aliasing artifacts in the reconstructed images. Such artifacts can be reduced using a variable-density spiral trajectory or a navigator echo, however at the cost of a longer scan time. Here, a novel iterative phase correction method is proposed to inherently correct for the motion-induced phase errors without requiring any additional scan time. In this initial study, numerical simulations and in vivo experiments are performed to demonstrate that the proposed method can effectively and efficiently correct for spatially linear phase errors caused by rigid-body motion in multishot spiral diffusion-weighted imaging of the human brain.
多回波螺旋成像技术是一种很有前途的替代技术，可以用于高分辨率弥散加权成像和弥散张量成像的回波平面成像。然而，在扩散加权梯度存在的情况下，主体运动会导致不同回波之间的相位不一致，从而导致重建图像中的信号丢失和混叠伪影。可以使用变密度螺旋轨迹或导航回波来减少这种伪影，但代价是扫描时间更长。这里提出了一种新的迭代相位校正方法，可以在不增加任何额外扫描时间的情况下，从根本上校正运动引起的相位误差。在这项初步研究中，进行了数值模拟和体内实验，以证明该方法可以有效地校正多回波螺旋弥散加权成像中人体大脑刚性运动引起的空间线性相位误差。
