结合脉冲梯度场(PFG)的选择性形状脉冲的相位特性研究

A STUDY OF PHASE PROPERTY OF SELECTIVE SHAPED PULSES IN COMBINATION WITH PFG

从转动矩阵理论与实验两方面研究了结合脉冲梯度场的选择性形状脉冲的相位特性，结果表明：单梯度自旋回波（ＳＰＦＧＳＥ）和双梯度自旋回波（ＤＰＦＧＳＥ）对于对称和反对称的形状脉冲，都能很好地克服其相位畸变；而双梯度自旋回波（ＤＰＦＧＳＥ）对于非对称的形状脉冲也能克服其相位畸变；双选择性单梯度自旋回波无法克服形状脉冲的相位畸变．

The phase properties of selective pulses in combination with PFG has been studied theoretically and experimentally. The results show that: for symmetric and antisymmetric shaped pulses, by using selective single PFG spin echo(SPFGSE) and selective double PFG spin echo (DPFGSE), pure in phase magnetization can be obtained in their whole excitation bandwidth. However, for other shaped pulses, the magnetization without phase distortions can only be obtained by using DPFGSE. Moreover, using doubly selective SPFGSE, neither symmetric (or antisymmetric) nor non symmetric shaped pulses can provide pure in phase magnetization.