DESIGN OF B-1-INSENSITIVE AND B-1-SELECTIVE RF PULSES BY MEANS OF STOCHASTIC OPTIMIZATION

Novel B-1-insensitive and B-1-selective RF pulses are derived by apply ing the stochastic optimization techniques of simulated annealing and threshold accepting. These B-1-insensitive pulses generate complete tr ansverse magnetization over a wide range of RF field strengths, wherea s the B-1-selective pulses act only over a predetermined range of RF f ield amplitudes. In combination with a surface coil, B-1-selective pul ses can be used for regional excitation without the application of Bo gradients. The performance of the two pulse types is verified experime ntally, and the problems arising in connection with their implementati on are discussed. (C) 1995 Academic Press, Inc.