Exhaustive Comparison of QSM Background Field Removal and Masking using a Realistic Numerical Head Phantom

Removing background fields is an important preprocessing step in QSM, enabling the reconstruction of fine tissue susceptibility variations in the region of interest (ROI) without being corrupted by susceptibility sources outside of this region. This requires a binary mask of the ROI and most background field removal methods are sensitive to the choice of mask. Here we compared 15 background field removal methods across 4 different masks. We found projection onto dipole fields (PDF) to perform best overall, although it is sensitive to the mask. V-SHARP and RESHARP were more robust to masking and showed good performance.