When adapting models of anatomical structures in a patient for diagnosis or therapeutic planning, an atlas (26) of predesigned anatomical structure models or image volumes can be accessed, and a segmentation of one or more such structures can be selected and overlaid on an a 3D image of corresponding structure(s) in a clinical image (52) of a patient. A user can click on an initially unapproved segmentation 5 landmark (72) on the patient image (52), reposition the unapproved landmark, and approve the repositioned landmark. Remaining unapproved landmarks (72) are then repositioned as a function of the position of the approved landmark (92) using one or more interpolation techniques to adapt the model to the patient image on the fly.