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Abstract #3439

Fast Gradient Ascent Pulse Engineering for parallel transmission pulse design in the small and large tip angle regimes

Natalia Dudysheva1, Joseph Brégeat1, Franck Mauconduit1, Aurélien Massire2, Nicolas Boulant1, and Vincent Gras1
1Université Paris-Saclay, CEA, NeuroSpin, CNRS, BAOBAB, Gif sur Yvette, France, 2Siemens Healthcare SAS, Courbevoie, France

Synopsis

Keywords: RF Pulse Design & Fields, RF Pulse Design & Fields

Motivation: Dynamic RF shimming in pTX at UHF faces two limitations: lengthy computational time of the GRAPE method or lack of precision of parametric approaches (e.g. kT-points).

Goal(s): To validate an alternative pulse parameterization, fastGRAPE, potentially offering a better trade-off between the performance and computational speed.

Approach: We compare GRAPE, fastGRAPE, and kT-point online and offline pulse designs for a commercial and a custom pTX RF coils at 7T using Bloch simulation and in vivo acquisitions.

Results: For short STA excitation, fastGRAPE yields comparable performances to GRAPE and outperforms kT-points. For inversion with the custom coil, online fastGRAPE provides the best flip angle accuracy.

Impact: With a flip angle accuracy comparable to GRAPE and a computation time comparable to kT-points, fastGRAPE presents a promising strategy both for online and offline dynamic RF shimming.

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Keywords