Meeting Banner
Abstract #3016

Calculation of B1 pulses for RF shimming at arbitrary flip angle using multiple transmitters

Ulloa J, Hajnal J, Callaghan M, Irarrazaval P, Guarini M
Pontificia Universidad Catolica de Chile

MRI at high field suffers from B1 inhomogeneity. Design in the Small-Tip-Angle (STA) regime allows B1 pulses that compensate for this. The excessive duration of such pulses has limited their use, but Parallel transmission can shorten excitation times. However, for higher flip angles the STA and existing parallel transmission formalism fail. In this work we extend the model of parallel transmission beyond the STA, by solving the Bloch equation for an array of spatially varying transmitters acting simultaneously. The method was tested by simulating B1 inhomogeneity correction for 90&[deg] excitation with 2 coils to achieve a predicted homogeneous excitation