2 A Computerized Approach for Morphological Analysis ofthe Corpus Callosum

Purpose. A new technique for analyzing the morphology of the corpus callo-sum is presented, and it is applied to a group of elderly subjects. Methods. The proposed approach normalizes subject data into the Talairach space using an elastic deformation transformation. The properties of this transformation are used as a quantitative description of the callosal shape with respect to the Talairach atlas, which is treated as a standard. In particular, a deformation function measures the enlargement/shrinkage associated with this elastic deformation. Inter-subject comparisons are made by comparing deformation functions. Results. This technique was applied to eight male and eight female subjects. Based on the average deformation functions of each group, the posterior region of the female corpus callosum was found to be larger than its corresponding region in the males. The average callosal shape of each group was also found, demonstrating visually the callosal shape diierences between the two groups in this sample. Conclusion. The proposed methodology utilizes the full resolution of the data, rather than relying on global descriptions such as area measurements. The application of this methodology to an elderly group indicated sex-related diierences in the callosal shape and size.