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Abstract #0208

Parallel Transmission Design of Multi-Pulse Sequences using Spatially Resolved Extended Phase Graphs (SREPG)

Shaihan J. Malik1, Hanno Homann2, Peter Brnert3, Joseph V. Hajnal1

1Robert Steiner MRI Unit, Imaging Sciences Department, MRC Clinical Sciences Centre, Hammersmith Hospital, Imperial College London, London, United Kingdom; 2Institute of Biomedical Engineering, Karlsruhe Institute of Technology, Karlsruhe, Germany; 3Philips Research, Hamburg, Germany

The Extended Phase Graph (EPG) formalism is a powerful means for predicting MR signals in sequences involving multiple RF pulses. At high field (3T+) the RF fields (B1) vary strongly in space, so predictions by the EPG algorithm are not valid everywhere. Parallel transmission enhances control of B1 enabling flip angle distributions to be modulated in both space and time. The effect of changing fields in this way can be predicted with spatially resolved EPG (SREPG). We demonstrate that pulses may be independently optimised for fast spin echo using SREPG leading to solutions not achievable by RF shimming alone.