Frederik Testud1, Maxim Zaitsev1
1Dept. of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany
Fast magnetic resonance imaging sequences such as GRE EPI are sensitive to spatial and temporal changes of B0 arising from susceptibility effects, temperature changes of the shims and motion of the object. This leads to time variant common image artefacts such as distortions and intensity losses. A field map is typically acquired at the beginning of the scan whereas neither temporal nor spatial changes of B0 are monitored during the experiment. As a possible remedy, we propose to use phantoms susceptibility-matched to air which are used to monitor the B0 evolution and determine the changes of the shim coefficients.