Scout-based Multi-Echo NAvigating (SMENA) for high temporal resolution motion and B0 estimation: applications to EPTI and multi-echo GRE

Motivation: Accurate high-temporal-resolution motion and B0 perturbation estimation have yet to be achieved for MRI. Goal(s): To develop a Scout-based Multi-Echo Navigator (SMENA) for joint motion and ΔB0 estimation at every 200 ms with minimal additional time. Approach: SMENA-navigator employs a 3.5-ms 6-echo sampling trajectory, with 4 navigators as a group to provide one estimate every 4 TR. SMENA-scout employs EPTI to provide rapid 4-mm multi-echo imaging in 3 seconds. The performance of SMENA was demonstrated on in vivo motion-corrupted EPTI and multi-echo GRE. Results: SMENA provided accurate motion and ΔB0 estimation at every 200ms, achieving high-quality correction for EPTI and multi-echo GRE. Impact: SMENA was developed for joint estimation of motion and ΔB0 at high temporal resolution. It can be flexibly applied to different sequences, providing accurate high-temporal-resolution motion and ΔB0 tracking, and potentially unleashing the power of MRI on motion-subject populations