| The goal of this dissertation is to develop mathematical and computer graphics techniques to enable precise and accurate combination of data from different medical imaging modalities into a single coordinate system for analysis and display.;Specifically, the problem addressed was to develop, test, and use techniques to combine magnetoencephalographic magnetic source imaging (MSI) data with magnetic resonance imaging (MRI) stacks of slices.;The "Pointers" technique was developed for interpolating the precise location of fiducial landmarks between slices in stacks of MRI slices. The "Pointers" are devices that use a material to produce a strongly contrasting converging pattern of dots and lines in the slices. This is used to precisely interpolate cardinal landmarks coordinate system. Various software and mathematical techniques, including the "Blobulator", were developed to precisely locate a Pointers traces in two dimensional slices. These locations on slices were used to construct optimal lines that join each sequence of blobby mark in three dimensional space between the slices to ideally intersect at a cardinal landmark. A best estimate for the precise location of a cardinal landmark in space, independent of the slice orientation, is solved from the system of lines.;In addition, the "SpiderWeb Algorithm", a new and topologically correct method of constructing three dimensional isosurfaces from volume density and volume gradient data, was developed. It is used, among other things, to reconstruct the skin isosurface for visually determining cardinal or fiducial landmarks. The advantage of this approach is that no Pointers hardware need be worn by the subject when recording a MRI study. In addition, brain surfaces, and other anatomic boundaries can be determined for further physical modeling studies.;These techniques have been applied to locate the neuronal sources of occipital alpha rhythm in human subjects. Data that define the positions of sources of individual spindles of alpha rhythm are related to features of cortical anatomy provided by MR Images. An analysis shows that they cluster near individual sulci of cerebral cortex by lying within the visual area of the longitudinal fissure. |
