Calibration‐Free GRAPE pTx Pulses for Homogeneous Spatial‐Selective Excitation at 7T

ABSTRACT Purpose Extend the universal pulse GRAPE formalism to pulses with a defined spectral response, and apply the concept to spatial selection. Methods We added Bloch simulations at several frequencies for each voxel to the pulse calculation to create universal spectrally‐selective GRAPE pulses. With a superimposed constant gradient field spatial selection was achieved. The method was tested in slice‐ and slab‐selective imaging experiments. Results Universal spatially‐selective GRAPE pulses increased FA homogeneity and SNR. In 2D gradient echoes, the SNR could be increased by approximately 6% compared to CP pulses, and in a slab‐selective TSE sequence, the SNR increased by 29% against k‐spokes pulses. Additionally, the slab‐selective GRAPE pulse proved to be more robust against deviations and is significantly shorter in comparison to k‐spokes pulses while maintaining a similar FA homogeneity. Conclusion Spatially‐selective universal GRAPE pulses exhibit superior performance compared to k‐spokes pulses. These short and robust pTx pulses hold potential for enhancing a wide range of imaging applications, thereby advancing 7T MRI technology closer to clinical use.