1. A method of image reconstruction for a magnetic resonance imaging (MRI) system comprising a plurality of coils, the method comprising: obtaining k-space scan data captured by the MRI system via the plurality of coils, the k-space scan data being representative of an undersampled region over time; iteratively reconstructing, with a processor, preliminary dynamic images for the undersampled region from the k-space scan data via optimization of a first instance of a minimization problem, the minimization problem comprising a regularization term weighted by a weighting parameter array; generating a motion determination indicative of an extent to which each location of the undersampled region exhibits motion over time based on the preliminary dynamic images; and iteratively reconstructing, with the processor, motion-compensated dynamic images for the region from the k-space scan data via optimization of a second instance of the minimization problem, the second instance having the weighting parameter array altered as a function of the motion determination.