颅脑梯度回波成像：呼吸伪影和导航回波矫正

梯度回波序列是磁共振成像中常用的脉冲序列,然而梯度回波对主磁场波动非常敏感,呼吸等生理运动引起的信号波动会导致图像伪影.该文报道了采用导航回波技术获取呼吸运动导致的局部磁场波动,用以矫正图像回波中随时间变化的相位波动,并将该技术应用于三维多回波梯度回波成像和T2＊定量图研究.研究结果显示：矫正前,相位波动幅度随回波时间增长而增大,模图和T2＊定量图在相位编码方向有明显伪影,并且男女呼吸伪影水平有显著性差异;矫正后,相位波动幅度大幅下降,图像伪影水平有显著性下降....

Full description

Saved in:
Bibliographic Details
Published in波谱学杂志 Vol. 31; no. 3; pp. 321 - 330
Main Author 董芳 裴孟超 王前锋 姜宏伟 李建奇
Format Journal Article
LanguageChinese
Published 上海市磁共振重点实验室，华东师范大学 物理系，上海 200062 2014
Subjects
T2^＊定量图
三维多回波梯度回波
呼吸伪影
导航回波
磁共振成像（MRI）
gradient echo
导航回波
MRI
T2定量图
T2mapping
三维多回波梯度回波
navigator echo
磁共振成像(MRI)
呼吸伪影
respiratory induced artifacts
Online AccessGet full text
ISSN1000-4556

Cover

More Information
Summary:梯度回波序列是磁共振成像中常用的脉冲序列,然而梯度回波对主磁场波动非常敏感,呼吸等生理运动引起的信号波动会导致图像伪影.该文报道了采用导航回波技术获取呼吸运动导致的局部磁场波动,用以矫正图像回波中随时间变化的相位波动,并将该技术应用于三维多回波梯度回波成像和T2＊定量图研究.研究结果显示：矫正前,相位波动幅度随回波时间增长而增大,模图和T2＊定量图在相位编码方向有明显伪影,并且男女呼吸伪影水平有显著性差异;矫正后,相位波动幅度大幅下降,图像伪影水平有显著性下降.
Bibliography:Images acquired with gradient echo sequences are susceptible to artifacts induced by frequency offsets varying in spatial and temporal dimensions. This study addressed how respiration-induced local field fluctuations affect the quality of brain images acquired with a three-dimensional multi-echo gradient echo sequence. It was shown that respiration-related artifacts can be corrected by acquire a one-dimensional navigator signal before the application of phase-encoding gradient in each phase-encoding step, which later can be used to correct respiration-related phase shifts during reconstruction to yield artifact-free images. Experimental results showed that both the respiration-related phase oscillations and image artifacts increased with echo time. It was also demonstrated that the phase fluctuations and image artifact levels in both the gradient echo images and T2＊ maps calculated from mutli-echo data reduced significantly after navigator echo phase correction.
DONG Fang, PEI Meng-chao, WANG Qian-feng, JIANG
ISSN:1000-4556