FIGURE 6.

Temperature change maps ( $\mathrm{\Delta }T$‐maps) from the phantom heating experiment using Double Echo Gradient Echo (DEGRE) data acquisition and different correction methods for 2 different slices. The last time point, 50 minutes after the acquisition of the reference image, was chosen. The first row displays the temperature increase maps for a middle slice. The second row displays the temperature change maps at the border of the phantom, in which we observed the formation of a dipole field from some motion‐induced susceptibility change. A, $\mathrm{\Delta }T$‐maps derived from DEGRE data without correcting for B₀ drift, B, $\mathrm{\Delta }T$‐maps with B₀ drift correction, C, $\mathrm{\Delta }T$‐maps after applying PDF for background field removal (BFR), D, $\mathrm{\Delta }T$‐maps after applying Laplacian boundary value (LBV) for BFR, E, difference of $\mathrm{\Delta }T$‐maps using the method shown in B) and D), F, difference of $\mathrm{\Delta }T$‐maps using projection onto dipole fields (PDF) and only drift correction, G, difference of $\mathrm{\Delta }T$‐maps PDF compared to LBV method. The white arrows point at areas where PDF overestimated the background field locally at the border of the phantom