Sparse Selective Excitation Pulse Design Using Adaptive Energy Threshold Method

Dong Chen^1,2, Folkmar Bornemann¹, Mika W. Vogel², Yudong Zhu³

Conventional 2D target excitation RF pulse design uses pre-determined k-trajectory based on the k positions required by Nyquist theorem. However Nyquist theorem is sufficient but not necessary condition for most practical target profile. Unlike the spatial encoding task in imaging, where the underlying image is unknown, in the case of excitation pulse design the target excitation profile is known a priori. In this work we propose a k space sparsifying method that exploits this prior-knowledge using Adaptive Energy-Threshold, which significantly reduces pulse duration and offers flexible tradeoff between excitation quality and pulse duration. The method was validated in phantom imaging experiments.