1. A method of performing computerized simulations of image-guided procedures, the method comprising: producing a digital image-based model of an anatomical structure based on medical image data; producing, based on the image-based model and extrapolated data, an extended model that represents the anatomical structure and adjacent anatomical regions not included in the medical image data; displaying a graphical representation of the extended model; and performing a computerized simulation of an image-guided procedure using the extended model.