Design of B1-Insensitive and B1-Selective RF Pulses by Means of Stochastic Optimization

NovelB1-insensitive andB1-selective RF pulses are derived by applying the stochastic optimization techniques of simulated annealing and threshold accepting. TheseB1-insensitive pulses generate complete transverse magnetization over a wide range of RF field strengths, whereas theB1-selective pulses act only over a predetermined range of RF field amplitudes. In combination with a surface coil,B1-selective pulses can be used for regional excitation without the application ofB0gradients. The performance of the two pulse types is verified experimentally, and the problems arising in connection with their implementation are discussed