Linear SAMER: linear motion optimization for scout accelerated retrospective motion estimation and reduction with linear+ reordering in MPRAGE

SAMER uses a fast reference scan (“scout”) and short additional guidance lines in each shot of an MPRAGE sequence (“linear+ reordering”) to calculate motion parameters. Optimization of rigid body motion parameters are typically nonlinear. In this work we exploit local linearity with SAMER to improve the performance. During motion estimation, the initial guess of motion parameters for a given shot is taken from the previous most similar shot. Similarity is determined by correlations of the linear+ guidance lines. Retrospective reconstructions of volunteer data show the proposed method has very good computation performance and can handle large motion well.