Tailored Shaping and Time Resampling Functions for Inversion Pulses at 7T
Aaron Christopher Hurley, Ron Coxon, Ali Al-Radaideh, Uwe Aickelin, Bai Li, Penny Gowland
International Society for Magnetic Resonance in Medicine (ISMRM): 17th Scientific Meeting and Exhibition | ISMRM | Published : 2009
The RF transmit field is severely inhomogeneous at ultrahigh field, due to both RF penetration and RF coil design issues. Here we utilised a search algorithm to produce inversion pulses tailored to take account of the heterogeneity of the RF transmit field at 7T. We created a slice selective inversion pulse which worked well over the range of RF amplitudes, while maintaining an experimentally achievable pulse length at 7T. The pulses were based on the FOCI technique as well as time dilation of functions but the RF amplitude, frequency sweep and gradient functions were all optimised using a Genetic Algorithm.