A Spatial Domain Method for the Design of RF Pulses in Multi-Coil Parallel Excitation
Grissom W, Yip C, Zhang Z, Stenger V, Fessler J, Noll D
University of Michigan
Current methods for RF pulse design in parallel excitation are based on the small-tip-angle approximation, which allows pulses to be designed using the excitation k-space formalism. In this work we investigated the performance of parallel excitation at large tip angles, using one such design method that is formulated in the spatial-domain. Pulses were scaled to produce tip angles up to 90 degrees, and excitation error was evaluated. We demonstrate that increased error at large tip angles can be attributed mainly to large RF magnitude in accelerated excitation, and can be mitigated using Tikhonov regularization in the design process.