一种快速自旋回波的受激回波伪影校正方法

A Method to Correct Stimulated Echo Artifact for Fast Spin Echo

研究了快速自旋回波产生受激回波的原理,以及受激回波与射频脉冲相位角之间的关系.针对快速自旋回波脉冲序列提出了一种受激回波伪影校正方法.通过两次激发分离出自旋回波与受激回波,然后调整预散相梯度的面积使受激回波与自旋回波中心重合,并修改180°回聚脉冲相位角使受激回波与自旋回波同相位.在1.5 T超导磁共振成像系统对校正方法进行了验证,经过受激回波伪影校正后,快速自旋回波图像的信噪比提高了57.08%,图像伪影降低了76.12%.实验结果表明,所提出的方法可以有效抑制受激回波对快速自旋回波成像的影响,提高了图像质量.

The principle of fast spin echo(FSE)producing stimulated echo and the relationship between stimulated echo and the phase angle of radio frequency pulse were investigated.For fast spin echo pulse sequence,a stimulated echo artifact correction method was proposed.The spin echo and stimulated echo were separated by two times of excitations,then the area of dispersion gradient was adjusted to make the center of stimulated echo coincide with that of the spin echo,and the phase angle of 180° refocusing pulse was modified to make the phase of stimulated echo and spin echo consistent.The correction method was tested and validated on a 1.5 T superconducting MRI scanner.After stimulated echo artifact was corrected,the signal to noise ratio of the FSE image was improved by 57.08%,while the image artifact was reduced by 76.12%.The experimental results showed that the proposed method can effectively suppress stimulated echo artifacts on FSE image and improve the image quality.