Scout accelerated motion estimation and reduction (SAMER).

Area of Science:

• Medical Imaging
• Magnetic Resonance Imaging (MRI)
• Computational Imaging

Background:

• Motion artifacts are a significant challenge in MRI, leading to image degradation and reduced diagnostic accuracy.
• Current retrospective motion correction techniques can be computationally intensive, increasing scan time and limiting clinical applicability.

Purpose of the Study:

• To develop and validate a navigator/tracking-free retrospective motion estimation technique.
• To achieve clinically acceptable reconstruction times for MRI scans with motion correction.

Main Methods:

• Scout accelerated motion estimation and reduction (SAMER) utilizes a low-resolution scout scan and novel sequence reordering.
• Motion states are determined by minimizing data-consistency error in a SENSE plus motion forward model, avoiding alternating optimization.
• The method was evaluated through simulations and in vivo studies across various motion scenarios and contrasts.

Main Results:

• Accurate motion trajectory estimation ( ~0.2 mm or degrees) was achieved using the accelerated scout scan.
• Clinically acceptable computation times (~4 s/shot) were demonstrated with a non-alternating motion search.
• Substantial artifact reduction and improved quantitative metrics were observed in vivo.
• Integration with Wave-CAIPI enabled rapid, high-quality imaging at up to 9-fold acceleration.

Conclusions:

• SAMER significantly enhances computational scalability for retrospective motion estimation and correction.
• The technique offers a promising solution for reducing motion artifacts in MRI without compromising reconstruction time.