Computer-assisted multidimensional atlas for functional stereotaxy.

Functional stereotactic operations are currently performed primarily for medically uncontrollable Parkinson's disease and pain. In contrast to the targets in neuro-oncology, those in functional stereotaxy cannot be represented directly by modern imaging methods. The target co-ordinates must therefore be calculated with the aid of special stereotactic atlases. These are publications in which a model brain has been constructed from autopsy examinations on a number of brains, or the data obtained have been compiled in the form of tables and histograms on which the calculation is then based. The target can then be determined based on the classic stereotactic landmarks and reference lines, such as the anterior commissure (AC), the foramen of Monro (FM), the posterior commissure (PC) or the base line FM-PC or AC-PC and the height of thalamus, taking into account the interindividually different anatomical proportions. Since the computational procedures involve repetitious algorithms, it was obvious that such procedures should be run by a computer program. For the most common stereotactic targets, we have developed a computer program for data storage on the one hand and computation and graphic output on the other. The output can be displayed on the monitor and can also be plotted out on paper or overhead transparency. Calibrating between the program and printer renders a 1:1 reproduction, i.e. the graph can be superimposed directly onto original x-rays or images from computed tomography or nuclear magnetic imaging. The graph can be plotted in the three dimensions of the Cartesian co-ordinate system. An additional dimension can be attained by simultaneously including and plotting the data from different atlases and thus from different authors, including one's own data. In addition to the information capacity which this system offers, it also makes possible a considerable reduction in the time for computing the target while at the same time increasing the reliability.