Automated measurement of latent morphological features in the human corpus callosum.

Our objective was to develop a novel factor-based analysis of the morphology of the corpus callosum and assess its applicability to the study of normal development, intelligence, and other subject characteristics. The contour of the corpus callosum was defined in the midsagittal planes of the MRI scans of 325 subjects, 6 to 88 years of age. The contours were coregistered, rescaled, and resampled to 50 points that were then entered into a principal components analysis with varimax rotation. The analysis yielded 8 factors for the contours of 138 healthy subjects. A second analysis of contours from 187 subjects in a patient group extracted 8 similar factors. Correlations of factor scores with conventional measures of callosum shape supported the construct validity of the assignment of morphological features to each of the factors. Correlations of factor scores with age, sex, handedness, ventricular volume, and IQ demonstrated the predictive validity of the factor structure and helped to define the neural correlates of these subject characteristics. We conclude that factor-based measures capture latent morphological features of the corpus callosum that are reliable and valid. Future studies will determine whether these novel measures are more closely related to neurobiologically important features of the corpus than are conventional measures of callosum size and shape.