Thoracic respiratory motion estimation from MRI using a statistical model and a 2-D image navigator

► Respiratory motion model that can predict intra- and inter-cycle motion variability. ► PCA-based model applied using a real-time 2-D MRI 'navigator'. ► Model application gives feedback on suitability of model to current breathing style. ► Motion model used to select optimal positioning for 2-D MRI 'navigator'. ► Technique demonstrated for purpose of MRI-based motion correction of PET imaging.