3-DIMENSIONAL RECONSTRUCTION OF THE AUDITORY CORTICAL AREAS FROM MAGNETIC-RESONANCE IMAGES

The future of neuromagnetic research will be highly dependent on the d evelopment of analysis procedures utilizing morphological information derived from magnetic resonance (MR) images. However, constraining the biomagnetic inverse problem by using such information may lead to ser ious misinterpretations if the reconstruction algorithm for the cortic al surface overlooks boundaries between grey matter and cerebrospinal fluid (CSF) or artificially generates them. The purpose of this study was to check as to what extent an advanced automatic three-dimensional reconstruction procedure is able to segment the cortical structures l ocated hidden in the Sylvian fissure (especially Heschl's gyrus and pl anum temporale). The procedure consisted of four processes: a coarse s egmentation, a refined segmentation of the white matter, a skeletoniza tion of the sulci and a segmentation of the cortical surface by concur rent region growing for brain and CSF. The reconstruction result for s ingle slices basically agrees with the impression obtained upon visual inspection of the original MR data. Photorealistic visualizations, sh owing a good qualitative agreement with anatomical images, suggest tha t the reconstructed surfaces are realistic and detailed enough to be a pplicable in source analyses of auditory evoked fields.