Wan X, Parker D L, Lee J N, Buswell H R, Gullberg G T
Department of Radiology, University of Utah, Salt Lake City 84132, USA.
Magn Reson Med. 1995 Oct;34(4):632-8. doi: 10.1002/mrm.1910340422.
Fast spin-echo (FSE) imaging techniques are very sensitive to the relative phase between the 90 degrees (excitation) RF pulse and the 180 degrees (refocusing) RF pulses. In this paper, it is demonstrated that a phase shift can be created between the excitation and refocusing pulses in such a manner that the received signal is divided into two components of distinctly different phase shifts. The nature of these two components is reviewed. It is demonstrated that ghosting artifacts will occur when images are reconstructed from this received signal. The ghosting is shown to be object dependent. A correction technique is presented which calculates the phase errors among different echoes based on measurements from a single echo train acquired without phase encoding gradients. The results in both phantom and human studies show that this method is capable of reducing the ghosting artifact in thin slice FSE images.
快速自旋回波（FSE）成像技术对90度（激发）射频脉冲和180度（重聚焦）射频脉冲之间的相对相位非常敏感。本文证明，可以在激发脉冲和重聚焦脉冲之间产生相位偏移，使得接收到的信号被分成两个具有明显不同相位偏移的分量。回顾了这两个分量的性质。结果表明，当从该接收到的信号重建图像时会出现重影伪影。重影显示与物体有关。提出了一种校正技术，该技术基于在没有相位编码梯度的情况下采集的单个回波链的测量结果来计算不同回波之间的相位误差。体模和人体研究的结果均表明，该方法能够减少薄层FSE图像中的重影伪影。
