1. A method, comprising: generating a mask from a set of mask images of an anatomy of a subject; applying the mask to acquired image data of the anatomy of the subject to generate a masked image, wherein applying the mask includes weighting the mask differently inside a first user-defined region of interest (ROI) of the image data than outside the first user-defined ROI, the weighting inside the first user-defined ROI determined independently of the weighting outside the first user-defined ROI; and responsive to a user input defining a second user-defined ROI, applying the mask to the masked image, wherein applying the mask to the masked image includes weighting the mask differently inside the second user-defined ROI than outside the second user-defined ROI.