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Abstract #3884

On the SAR Averaging Nature of Parallel Excitation Pulses and Its Impact on Conservative Worst-Case Analysis

Stefanie Buchenau1, Martin Haas1, Jrgen Hennig1, Maxim Zaitsev1

1Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany

To assure patient safety during parallel excitation experiments, monitoring of the RF pulses is necessary. If no additional hardware is available that measures RF phases a common approach is a conservative worst-case analysis that assumes absolutely constructive interference of the electric fields. This work shows that due to the varying phase settings during a parallel excitation pulse, worst-case SAR that may occur for single time steps is averaged over the pulse duration. This still holds true if the designed RF pulse is erroneously executed. Therefore conservative worst-case analysis overestimates SAR and it is possible to relax RF power limits that are based on this worst-case analysis.