Implications of Undersampling Strategy for GRAPPA-accelerated QSM and R2* Map Acquisition

Motivation: Similar scan durations are achievable with different acceleration strategies, introducing ambiguity in quantitative susceptibility mapping (QSM) acquisition protocols. Goal(s): Characterization of the influence of acceleration strategy on QSM and R2* reconstructed from GRAPPA-accelerated multi-echo gradient echo data Identification of a QSM-specific recommended acceleration strategy Approach: Three subjects were imaged at 3 T using multi-echo gradient-echo scans prospectively acquired with 9 parallel imaging acceleration strategies. QSM and R2* computed using MEDI and ARLO were compared against reconstructed maps from fully-sampled data. Results: Partial Fourier acquisition reduces measurement precision compared to groundtruth at all GRAPPA factors. GRAPPA 3 does not significantly compromise precision or accuracy. Impact: Strict utilization of acceleration strategies that do not rely on Partial Fourier acquisition can improve QSM accuracy, and remove ambiguity in protocol design.