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Abstract #4932

Local SAR Constrained Hotspot Reduction by Temporal Averaging

Ingmar Graesslin1, Christian Steiding1, Bjoern Annighoefer2, Julia Weller1, Sven Biederer3, David Brunner4, Hanno Homann1, Ferdinand Schweser5, Ulrich Katscher1, Klaas Pruessmann4, Peter Boernert1

1Philips Research Europe, Hamburg, Germany; 2TU Hamburg-Harburg, Hamburg, Germany; 3Institute of Medical Engineering, University of Lbeck, Lbeck, Germany; 4University and ETH Zurich, Zurich, Switzerland; 5IDIR / University Clinics, Jena, Germany

With increasing field strength the local specific absorption rate (SAR) becomes a limiting factor for many MR imaging applications. Minimal SAR RF pulses can be selected from the large solution space due to the extra degrees of freedom in the RF pulse design. This paper extends the recently proposed temporal averaging approach for local SAR reduction with multiple local SAR constraints. It successively applies multiple RF pulses with similar target excitation patterns, but different spatial SAR distributions, for averaging out local hotspots. The concept was validated by simulations and initial experiments on an 8-channel TX MRI system.