1. A system for annotating a three-dimensional medical image of an anatomic object of a patient, the three-dimensional medical image being based on a signal obtained from a medical image scanner arranged for scanning the three-dimensional anatomic object of the patient, the system comprising: a display device that displays at least a part of the three-dimensional medical image of the anatomic object of the patient; a three-dimensional interaction device comprising a surface having a typical shape of at least part of a kind of anatomic object represented by the three-dimensional anatomic object of the patient, wherein the interaction device provides a signal that is indicative of a location on the surface that is indicated by a user; and a processor that: registers the three-dimensional medical image of the anatomic object of the patient to an electronic representation of the shape of the surface of the interaction device to obtain a registration: receives the signal that is indicative of the location on the surface indicated by the user maps the indicated location to a corresponding point of the medical image of the anatomic object of the patient based on the registration; receives a user provided annotation; and attaches the user provided annotation to a position within the three-dimensional medical image of the anatomic object of the patient corresponding to the location on the surface indicated by the user.