摘要
磁共振成像系统中的有源匀场线圈主要用来对磁场的非均匀性进行实时校正,因此需要在短时间内算出匀场电流。根据MRI理论中FID信号强度与磁场均匀性的正比关系,本文在间接计算法的基础上提出了一种电流迭代优化算法。该方法不受线圈硬件参数影响,可以快速算出匀场电流进行磁场校正,平均耗时不到3min。实验结果表明,匀场后磁场均匀性可大幅提高,图像质量明显改善。
The active shim coils of MRI system are mainly used to correct the unhomogeneity of magnetic field in real time. So it is necessary to work out the shimming current in a short time, Based on the direct proportion relationship between FID signal and magnetic field homogeneity in MRI theory, a novel iterative optimization algorithm is presented to calculate the current. The calculation by this algorithm is independent of coils configuration parameters and the shimming current can be worked out to compensate the unhomogeneous magnetic field in less than 3 minutes. The experiment results show that this method can evidently improve the magnetic field homogeneity and the quality of image.
出处
《北京生物医学工程》
2007年第5期466-469,共4页
Beijing Biomedical Engineering
基金
宁波市科技创新项目(2003D10057)
中国科学技术大学研究生创新基金(KD2005045)资助
关键词
有源匀场
匀场线圈
磁场均匀度
FID
active shimming
shim coils
magnetic field homogeneity
FID
