Rapid and accurate navigators for motion and B₀ tracking using QUEEN: Quantitatively enhanced parameter estimation...

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Medical Physics
• Image Reconstruction

Background:

• Existing MRI methods estimate motion or B0 field perturbations separately using navigator data.
• These methods often rely on low-resolution scout images and are limited in temporal resolution and flexibility.

Purpose of the Study:

• To develop a framework (QUEEN) for joint estimation of rigid motion and B0 field perturbations in brain MRI.
• To enable high-temporal resolution estimates using short, single navigators acquired at arbitrary timings within any MRI sequence.

Main Methods:

• Proposed QUEEN (QUantitatively Enhanced parameter Estimation from Navigators) framework for combined motion and B0 estimation.
• Introduced quantitative scout (Q-Scout) acquisition to predict contrast-matched scout data for each navigator.
• Integrated tailored navigator trajectories, Q-Scout, and B0 field into a motion-informed parallel-imaging framework.

Main Results:

• Simulations and in vivo experiments demonstrated the necessity of modeling B0 perturbations for accurate motion estimation.
• Tailored navigator trajectories are crucial for robust joint estimation of motion and B0.
• Contrast-matched scouts are essential for parameter estimation from multi-contrast navigator data.
• Retrospective reconstruction showed improved image quality using Q-Scout and QUEEN.

Conclusions:

• Developed a framework for joint estimation of rigid motion and B0 perturbations from MRI navigators.
• Combining contrast-matched scouts with tailored trajectories enables flexible navigator deployment.
• Achieved higher temporal resolution for motion and B0 perturbation estimates.