An Open-Source Self-navigated Multi-Echo Gradient Echo Acquisition for R2* and QSM mapping using Pulseq and Model-Based Reconstruction

We propose an open-source multi-echo GRE sequence and reconstruction algorithms for rapid acquisition and harmonization of QSM. This is implemented using Pulseq, where different sampling patterns are used across echoes to provide complementary information and facilitate the proposed MOdel BAsed (MOBA) reconstruction. MOBA estimates M0, R2* and frequency maps using nonlinear optimization and is implemented in BART to facilitate dissemination. B0 correction is performed using 1D navigators acquired during the crusher gradients in each repetition. Motion navigators inserted in the sequence permit robust estimation of motion parameters with time frames of ~13seconds, and will lend themselves to retrospective motion correction.