A method includes acquiring a series of images over time from a liver of a subject injected with a contrast bolus, wherein the series of images span multiple phases of the contrast-enhanced scan. The method includes inputting the series of images into a trained neural network framework and utilizing the trained neural network framework to separately segment an aorta and a portal vein from each image of the series of images. The method includes utilizing the trained neural network framework to select exact respective time points for at least an aortic phase and a portal-venous phase based on the aorta and the portal vein segmented in each image. The method includes outputting a first set of images associated with the aortic phase and a second set of images associated with the portal-venous phase based on the exact respective time points selected for the aortic phase and the portal-venous phase.