1. A method for linking visually dissimilar local regions of a pair of images, comprising: obtaining at least first and second digitized images of an object; using a 3D landmark detection method to determine a correspondence between a portion of the first digitized image and a portion of the second digitized image, the portion of the first digitized image comprises a point of interest selected by a user as a user-defined click point, the portion of the first digitized image being a location within the first digitized image where a registration accuracy must be higher than registration accuracy in other portions of the first digitized image and the correspondence is determined using geometrical relations between the user-defined click point in the first digitized image and a predetermined point in the second digitized image; and the 3D landmark detection method is a learning based detection method comprising: collecting whole-body volumes into a database as training volumes; manually labeling landmarks of interest for each training volume; aligning the training volumes using a weighted-alignment algorithm that gives a particular landmark of interest for a given training volume higher weights than other landmarks; cropping data centered around the particular landmark of interest for a given training volume to generate positive training examples that contain the particular landmark of interest; cropping data randomly elsewhere in the training volumes to generate negative training examples; developing a discriminative classifier using the database of positive and negative training examples; and performing a novel whole-body volume scan of the object to obtain a novel whole-body volume and detect a landmark in the novel whole-body volume; wherein windows that are classified as positive by the classifier are returned as potential detection results, and detected windows are ranked based on their responses, and the detected window with the highest response value has the highest likelihood of being the detected landmark in the novel whole-body volume.