摘要
研究了涡流对永磁磁共振扩散加权平面回波成像的影响,提出了一种针对永磁磁共振成像系统的涡流补偿算法,并对扩散加权EPI序列由于剩余涡流引起的相位误差提出了一种补偿方法.在0. 35 T永磁型磁共振成像系统上对算法进行了验证,不同的梯度方向经过涡流预加重补偿后,涡流最少也会降至未补偿前的1/15.对涡流补偿和未补偿的模体扩散加权EPI图像进行了比较,经过两次补偿后,图像几何畸变会降低5%,图像伪影会降低1/3.实验结果表明,所提出的算法可以有效抑制因涡流引起的扩散加权EPI伪影及畸变.
The effect of eddy currents on diffusion-weighted echo-planar imaging(EPI)was investigated for permanent magnetic resonance imaging(MRI)scanner.An automatic eddy currents calibration algorithm was presented,and a compensation method for phase errors caused by residual eddy currents in diffusion-weighted EPI was proposed.The method was tested and validated on a 0.35 T permanent magnet MRI scanner.For three different gradient directions after pre-emphasis compensation,the eddy currents reduced to at least 1/15 of that before compensation.The diffusion-weighted EPI images with and without eddy currents compensation were compared.After two times of compensations,the geometric distortion was reduced by 5%and artifacts was reduced by 1/3.The experimental results showed that the proposed algorithm can effectively suppressed the diffusion-weighted EPI artifacts and distortions caused by eddy currents.
作者
王艳飞
杨金柱
康雁
WANG Yan-fei;YANG Jin-zhu;KANG Yan(College of Medicine and Biomedical Information Engineering,Northeastern University,Shenyang 110169,China;Key Laboratory of Intelligent Computing in Medical Image,Ministry of Education,Northeastern University,Shenyang 110169,China;School of Computer Science&Engineering,Northeastern University,Shenyang 110169,China;College of Health Science and Environmental Engineering,Shenzhen Technology University,Shenzhen 518118,China)
出处
《东北大学学报(自然科学版)》
EI
CAS
CSCD
北大核心
2020年第7期1048-1053,共6页
Journal of Northeastern University(Natural Science)
基金
国家自然科学基金青年基金资助项目(61602101).
关键词
磁共振成像
平面回波成像
扩散加权成像
涡流
预加重
MRI(magnetic resonance imaging)
EPI(echo-planar imaging)
diffusion-weighted imaging
eddy currents
pre-emphasis