Since the mid seventies many researchers are dealing with the problem of non invasive diagnosis. One way of doing this are the imaging techniques used in almost every clinical environment, e.g. classic X-rays, ultrasound, Computed Tomography (CT), Magnetic Resonance Imaging (MR), or more experimental techniques like PET or SPECT. The large amount of information contained in such images produced with imaging devices of the above categories is not easy to analyse. Hence, the images obtained have to be processed in a way that will yield 3-D-looking images similar to those in anatomical atlases. This chapter aims at the presentation of the most important methods in medical 3-D-visualization and some representative work for each method discussed.

Furthermore there will be a description of some possibilities to compensate for the drawbacks of visualization that include speed, integration in clinical routine and non automatic segmentation. For speeding up the visualization of volume images some parallelization techniques will be presented. In the last part of this chapter the reader will find some guidelines for the design of a user-centered graphical interface in order to allow less experienced computer users, like medical personnel, to use some visualization algorithms in a comprehensive and less time-consuming way. Such interfaces might allow a fast integration in clinical routine.

As the following presentation of 3-D visualization in medicine is supposed to be a survey that will serve as an introduction to the concepts, we avoid presenting mathematical formulas for the models presented and concentrate on a verbal description.