摘要
目的开发并验证一种基于相位线性度的多回波场图拟合算法,以提高定量磁化率分布图的图像质量。材料与方法提出了一种多回波场图拟合的改进算法,其通过场图线性拟合的残差来判断数据点相位的可靠性。采集15名健康被试的模图和相位图,分别采用常规算法和改进算法拟合得到场图,再经过场图解缠绕、背景场去除和磁化率反演等步骤获得磁化率分布图。选取黑质、红核、尾状核、苍白球和壳核作为感兴趣区,对比研究了两种算法得到的磁化率分布图上感兴趣区的噪声水平。结果采用改进的场图拟合算法后,定量磁化率图像质量得到明显提高,伪影得到明显抑制。双侧黑质、右侧红核等区域的噪声水平显著下降。结论该文提出的一种改进的定量磁化率成像多回波场图拟合算法可以提高磁化率分布图的图像质量。
Objective:To develop a new multi-echo field fitting algorithm to improve the image quality in quantitative susceptibility mapping(QSM).Materials and Methods:Conventional multi-echo field fitting algorithm may run into difficulty in the presence of poor linearity of phase data in QSM.In this study,we developed an improved multi-echo field fitting algorithm based on evaluation of phase linearity with echo time.Magnitude and phase images from 15 healthy participants were acquired.Conventional algorithm and improved algorithm were first used to perform the field fitting,respectively.After a magnitude map guided spatial field unwrapping and background field removal,the remaining tissue field was inverted to generate a susceptibility map.Substantia nigra,red nucleus,caudate nucleus,globus pallidus and putamen were selected as regions of interest.Non-parametric paired samples Wilcoxon signed rank test was conducted to compare the noise difference in the regions of interest on susceptibility maps with conventional algorithm and improved algorithm.Results:The proposed algorithm improved the accuracy of field fitting and reduced the image artifacts in susceptibility map.The noise of bilateral substantia nigra,right red nucleus decreased significantly.Conclusions:The proposed multi-echo field fitting algorithm can be used to improve the image quality of susceptibility map when poor linearity is present in phase data.
作者
陈佳林
童睿
赵羽
王乙
李建奇
CHEN Jialin;TONG Rui;ZHAO Yu;WANG Yi;LI Jianqi(Shanghai Key Laboratory of Magnetic Resonance,School of Physics and Electronic Science,East China Normal University,Shanghai 200062,China;Department of Radiology,Weill Medical College of Cornell University,New York,NY 10021,USA)
出处
《磁共振成像》
CAS
2020年第1期50-54,共5页
Chinese Journal of Magnetic Resonance Imaging
关键词
定量磁化率成像
多回波场图拟合
相位线性度
quantitative susceptibility mapping
multi-echo field fitting
phase linearity
