1. A method for lesion matching in medical images, said method comprising: obtaining a first set of computed tomography (CT) images fused to a first set of positron emission tomography (PET) images at a first point in time that form a baseline fused data set; obtaining a second set of CT images fused to a second set of PET images at a different second point in time to form a follow-up fused data set; performing a rigid registration between the first set of CT images and the second set of CT images to define an anatomical mapping between the baseline and follow-up fused data sets; identifying a baseline bookmarked region of the first set of PET images using a plurality of bookmarks; performing a local non-rigid registration between the baseline bookmarked region, that is encompassed by the plurality of bookmarks, and a corresponding region in the second set of PET images; automatically propagating the bookmarks in the first set of PET images to the second set of PET images utilizing the local non-rigid registration, the anatomical mapping defined by the rigid registration between the baseline and follow-up fused data sets; and displaying the bookmarks in the corresponding region in the second set of PET images to automatically match lesions on at least one PET image in the second set of PET images.