SAR Safety Issues in Case of Partial Coil Loading

Peter Vernickel¹, Christoph Leussler¹, Daniel Wirtz¹, Ingmar Graesslin¹

MR imaging demands an exact control of the SAR to ensure patient safety. Dedicated hard- and software is used to measure the complex coil currents I, coil quality factor Q, or reflection coefficient Sxx to ensure that the scan runs within allowed limits. However, uncertainties may exist when relying on the verification of one of the mentioned quantities, because this can lead to ambiguous results when characterizing the complex arrangement of coil and load. This abstract demonstrates an example for a situation in which measuring I, Q or S11 while slightly modifying arrangement of coil and load leads to misleading results for SAR monitoring.