An Analysis of RF Pulse Apodization in Parallel Spatially Selective Excitation

This paper presents an analysis of the effect of RF apodization for parallel spatially selective excitation in MRI. Using the small tip-angle approximation and the k-space interpretation, the analysis shows that for multidimensional multi-channel parallel excitation, limited RF pulse duration can lead to ringing excitation artifacts, similar to the truncation artifacts. Proper weighting of RF pulses can significantly reduce these artifacts, which is important for restricting field of excitation with minimal side lobes. Simulation results using a four-channel system in 1-D and 2-D experiments were shown to verify the analysis