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Abstract #4414

Evaluation of Virtual Observation Points for Local SAR Monitoring of Multi-Channel Transmit RF Coils at 7 Tesla

Andreas K. Bitz1, Rene Gumbrecht2, 3, Stephan Orzada1, Hans-Peter Fautz2, Mark E. Ladd1, 4

1Erwin L. Hahn Institute for MRI, University of Duisburg-Essen, Essen, Germany; 2Siemens Healthcare, Erlangen, Germany; 3Department of Physics, Friedrich-Alexander University, Erlangen, Germany; 4Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany

SAR monitoring for multi-Tx approaches in high-field MRI is a challenging task, since several channels have to be supervised simultaneously and the local SAR has to be considered. For computationally efficient online local SAR supervision, the concept of virtual observation points (VOPs) has been proposed. Here, VOP models are evaluated for realistic exposure configurations with two 7T RF coils, an 8-channel head and an 8-channel body coil, and for three body models. For all configurations and for a reasonable maximum overestimation of about 10%, the number of VOPs is smaller than 500, for which online monitoring has been successfully tested.

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