Measurement of the corpus callosum using magnetic resonance imaging: analyses of methods and techniques

Since the first postmortem report of sex-related differences in the size of the human corpus callosum, a number of studies on sex differences have been published, but results conflicted. The aim of this review was not to assess the possible existence and magnitude of sex variations in the size of the corpus callosum but to analyze methodological differences in several studies using Magnetic Resonance Imaging to investigate the sexual dimorphism in the size of the corpus callosum. Methodological problems arise at several steps of the method: sampling, imagery techniques, and measurements. Moreover, the means of callosal areas obtained by the nine reported studies are significantly different. The hypothesis that methodoiogical differences could explain these differences is supported by statistical results. A common method for investigating sex-related differences in callosal morphology appears necessary to resolve the question of a real sexual dimorphism of the corpus callosum and its subregions.