Simonetti O P, Duerk J L, Chankong V
Department of Radiology, MetroHealth Medical Center, Cleveland, Ohio.
Magn Reson Med. 1993 Apr;29(4):498-504. doi: 10.1002/mrm.1910290411.
This manuscript describes a method of gradient waveform design by nonlinear constrained optimization. Methods of formulation and solution of the waveform optimization problem are briefly described for minimization of root mean squared current and minimization of waveform moments. Waveforms generated using these objectives are presented and compared with those obtained with other objectives. The method uses waveforms which are defined as a set of discrete amplitudes in order to remove artificial constraints on waveform shape imposed by "multilobe" designs. These point-to-point amplitudes are the parameters determined in the optimization procedure which includes knowledge of the specific imaging conditions and the specific gradient hardware system. Some beneficial results of this design approach are: a) physically realizable waveforms which optimally achieve specific imaging and motion artifact reduction goals, b) waveforms which are guaranteed to be optimal with respect to one of several possible objective, c) less reliance on the experience of the designer, and d) a potential reduction in waveform design time.
本手稿描述了一种通过非线性约束优化进行梯度波形设计的方法。简要介绍了波形优化问题的公式化和求解方法，以实现均方根电流最小化和波形矩最小化。展示了使用这些目标生成的波形，并与使用其他目标获得的波形进行了比较。该方法使用定义为一组离散幅度的波形，以消除“多叶”设计对波形形状施加的人为约束。这些点对点幅度是在优化过程中确定的参数，其中包括特定成像条件和特定梯度硬件系统的知识。这种设计方法的一些有益结果是：a）物理上可实现的波形，可最佳地实现特定的成像和减少运动伪影目标；b）相对于几种可能目标之一保证为最优的波形；c）减少对设计者经验的依赖；d）潜在地减少波形设计时间。
