Motion guidance lines for robust data consistency–based retrospective motion correction in 2D and 3D MRI. Issue 5 (6th February 2023) - Polak, Daniel
Abstract : Purpose: To develop a robust retrospective motion‐correction technique based on repeating k‐space guidance lines for improving motion correction in Cartesian 2D and 3D brain MRI. Methods: The motion guidance lines are inserted into the standard sequence orderings for 2D turbo spin echo and 3D MPRAGE to inform a data consistency–based motion estimation and reconstruction, which can be guided by a low‐resolution scout. The extremely limited number of required guidance lines are repeated during each echo train and discarded in the final image reconstruction. Thus, integration within a standard k‐space acquisition ordering ensures the expected image quality/contrast and motion sensitivity of that sequence. Results: Through simulation and in vivo 2D multislice and 3D motion experiments, we demonstrate that respectively 2 or 4 optimized motion guidance lines per shot enables accurate motion estimation and correction. Clinically acceptable reconstruction times are achieved through fully separable on‐the‐fly motion optimizations (˜1 s/shot) using standard scanner GPU hardware. Conclusion: The addition of guidance lines to scout accelerated motion estimation facilitates robust retrospective motion correction that can be effectively introduced without perturbing standard clinical protocols and workflows.