Radiofrequency pulse design using nonlinear gradient magnetic fields.

ABSTRACT:

Purpose

An iterative k-space trajectory and radiofrequency (RF) pulse design method is proposed for excitation using nonlinear gradient magnetic fields.

Theory and methods

The spatial encoding functions (SEFs) generated by nonlinear gradient fields are linearly dependent in Cartesian coordinates. Left uncorrected, this may lead to flip angle variations in excitation profiles. In the proposed method, SEFs (k-space samples) are selected using a matching pursuit algorithm, and the RF pulse is designed using a conjugate gradient algorithm. Three variants of the proposed approach are given: the full algorithm, a computationally cheaper version, and a third version for designing spoke-based trajectories. The method is demonstrated for various target excitation profiles using simul

SUBMITTER: Kopanoglu E 

PROVIDER: S-EPMC4362804 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature