Graesslin, I., Weller, J., Schweser, F., Annighoefer, B., Biederer, S., Katscher, U., … Börnert, P. (2008). SAR Hotspot Reduction by Temporal Averaging in Parallel Transmission.
Graesslin, I., J. Weller, F. Schweser, B. Annighoefer, S. Biederer, U. Katscher, T. Nielsen, P. Harvey, and P. Börnert. “SAR Hotspot Reduction by Temporal Averaging in Parallel Transmission” (2008).
Graesslin, I., et al. SAR Hotspot Reduction by Temporal Averaging in Parallel Transmission. 2008.
Introduction The local specific absorption rate (SAR) becomes a limiting factor for many MR imaging applications with increasing field strength. However, tailoring of the underlying electric fields (E-fields) in the RF pulse design process is possible when using parallel Tx systems. Different approaches exist to reduce SAR in parallel transmission. Minimal SAR RF pulses can be selected from the large solution space due to the extra degree of freedom in the RF pulse design [1-4]. This paper presents a novel approach for local SAR reduction by exploitation of the temporal degree of freedom of multi-shot imaging sequences. It is based on successive application of RF pulses with the same target excitation pattern, but different spatial distributions of SAR, levelling out by time averaging. The concept was validated by simulations. Both computation of RF pulses and spatial SAR distributions were significantly accelerated implementing it on a graphicsprocessing unit (GPU). The local SAR calculation was carried out in real-time for a whole body bio-mesh according to .