A method for localizing an internal body structure during an image-guided procedure that includes obtaining a three dimensional image of a body portion containing a targeted structure and selected reference structures; determining a set of landmark point coordinates for defining the location of each of the targeted and reference structures; computing triangulation parameters relating the location of the landmark points for the targeted structure and the reference structures; and, during an image-guided procedure, using the computed triangulation parameters to plot an estimated location of the targeted structure on an intra-operative image in which the reference structures have been identified.