一种改进的EPI伪影校正算法  

An Improved Method of Ghost Correction Algorithm for EPI

作　　者：王世杰[1] 罗立民[1] 

机构地区：[1]东南大学影像科学与技术实验室,南京210096

出　　处：《信号处理》2007年第4期568-572,共5页Journal of Signal Processing

基　　金：国家重点基础研究发展计划资助项目(项目编号:2003CB716102)

摘　　要：EPI是功能磁共振成像(fMRI)广泛采用的一种扫描技术。成像物体的磁敏感性、化学位移、静磁场不均匀性以及系统硬件性能的不完善等因素导致EPI图像在相位编码方向存明显的ghost伪影,严重破坏了图像的质量。研究基于图像的后处理方法校正EPI伪影具有明显的实际临床应用价值。首先分析了现行相位校正算法和相位恢复算法的不足之处,然后提出了一种改进的EPI伪影校正算法。改进的算法充分利用两种方法的优点,并克服了各自的缺点,较好地实现了伪影校正。通过对实际的phantom图像处理,阐明了改进算法的稳定性及可靠性。Echo planar imaging （EPI） is a pervasive technique for functional MRI. The ghost for EPI in phase-encode direction, resulted from susceptibility, chemical shift, static field in-homogeneity, and hardware imperfections ,degenerate the image quality severely. The research of image-based methods to correct ghost for EPI has significant value in clinical application. The disadvantages of both phase correction algorithm and phase retrieval algorithm are discussed, and an improved method of ghost correction algorithm is reported. The improved method takes advantage of the merits of two previous algorithms, overcoming the disadvantages of them, to reduce the ghost for EPI effectively. The experimental results with an actual phantom scan show the stability and reliability of the improved method.

关 键 词：磁共振成像 回波平面成像 伪影校正 

分 类 号：TP183[自动化与计算机技术—控制理论与控制工程]