磁共振信号在双极性梯度磁场下自旋回波序列中的理论推导  

Derivation of MRI signal in spin echo sequence with bipolar gradient magnetic field

作　　者：苏晋 袁小燕 SU Jin YUAN Xiao-yan(Department of Basic Medicine, Chongzhi Medical College, Changzhi 046000, Shanxi, Chin)

机构地区：[1]长治医学院基础医学部物理教研室,山西长治046000

出　　处：《生物医学工程与临床》2017年第5期481-484,共4页Biomedical Engineering and Clinical Medicine

摘　　要：在MRI中,序列的选择比较丰富,同时也对医学影像的质量有着重要的意义。描述磁共振的基础理论一般采用Bloch方程。如何利用Bloch方程计算和分析复杂的序列对MRI信号的影响,是理解和改善MRI的理论基础。在旋转坐标系下,通过矩阵形式下Bloch方程的解的形式,对序列结构中不同阶段的磁共振信号按照时间先后进行递推,双极性梯度磁场下的自旋回波(SE)序列对MRI信号的影响和理论公式得到推导和数值分析,从结果上验证了其正确性,也为临床上越来越复杂的成像序列的选择和MRI信号的分析提供了理论基础。Many different MR sequences are carried in MRI, which showed important effect on the quality of medical images.The basic theory generally used in MRI is Bloch equation. The study of Bloch equation in calculating and analyzing the effects of complex sequences on MRI signals is the theoretical basis for understanding and improving MRI. In the rotating coordinate,by means of the solution of the Bloch equation in matrix form, the magnetic resonance signals of different stages in the se-quence structure were conducted recursive process in chronological order, the influence of spin echo（SE） sequence on MRI signal under bipolar gradient magnetic field and theoretical formula were derived and analyzed numerically, and the validity was proved by the results. Meanwhile, it provides the theoretical basis for the clinical choice of different complex MRI sequences and the analysis of MRI signals.

关 键 词：磁共振成像(MRI) BLOCH方程 双极性梯度磁场 自旋回波(SE)序列 

分 类 号：R445.2[医药卫生—影像医学与核医学]