Irina Brote1,2, Stephan Orzada1,2, Oliver Kraff1,2, Stefan Maderwald1,2, Harald H. Quick1,2, Pedram Yazdanbakhsh3, Klaus Solbach3, Karsten Wicklow4, Achim Bahr5, Thomas Bolz5, Mark E. Ladd1,2, Andreas K. Bitz1,2
1Erwin L. Hahn Institute for MRI, Essen, Germany; 2Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany; 3University Duisburg-Essen, Duisburg, Germany; 4Siemens Healthcare, Erlangen, Germany; 5IMST GmbH, Kamp-Lintfort, Germany
SAR prediction and monitoring are major concerns for MR systems, especially at ultra-high field where multi-transmit systems have recently been introduced to overcome problems concerning B1 inhomogeneity. The aim of this work was to design and implement a SAR prediction and monitoring system for a self-built RF shimming system on a 7T whole-body scanner for use in humans. All channels have to be supervised, and an individual SAR prediction has to be performed for each exposure scenario. Before scanning, the maximum permissible power for each channel is computed using numerical field distributions. During scanning, real-time monitoring has been implemented using a FPGA card which samples each channel and calculates time-averaged power.
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