1. A method of minimally invasive surgery comprising the steps of: imaging a region of interest of a patient using a three-dimensional diagnostic imaging technique to generate volumetric image data in a volumetric image coordinate system; as a surgical instrument is inserted into the region of interest, generating a series of fluoroscopic projection images of the region of interest including the surgical instrument in a fluoroscopic image coordinate system for monitoring movement of the surgical instrument into the region of interest; electronically correlating the fluoroscopic image coordinate system and the volumetric image coordinate system; and, displaying the volumetric image data together with at least a portion of said series of fluoroscopic images superimposed on the volumetric image data to show an image of said surgical instrument relative to said volumetric image data.