ANALYSIS OF CROSS-SECTIONAL AREA MEASUREMENTS OF THE CORPUS-CALLOSUM ADJUSTED FOR BRAIN SIZE IN MALE AND FEMALE SUBJECTS FROM CHILDHOOD TO ADULTHOOD

Interest in anatomic evaluation of the corpus callosum is based upon t he expectation that its function will be influenced by its structure. Using MR images, the size of the corpus callosum was determined by mea suring its area in the midsagittal plane. A callosal index was calcula ted for each subject by dividing the callosal size by cerebral size, a lso measured from the MR image. This callosal index was designed to al low comparison of callosal size between different groups, despite diff erences in brain size that existed between the groups. The validity of this index was supported by the statistically significant, positive c orrelation between measured callosal area and cerebral size. Using MR images and the callosal index, adult males were shown to have a larger corpus callosum and larger cerebrum, compared to adult females. Howev er, the callosal index was identical for male and female subjects. Thi s demonstrated there relative size of the callosum was the same for ma les and females. Childhood development of the corpus callosum was docu mented through the first two decades of life by a progressive increase in the callosal index. In adults, cerebral atrophy caused a decline i n callosal size, but no decline due to simple advancing age was found in normal adult subjects. This use of cerebral size to calculate a cal losal index appeared to be useful in comparing callosal size between s ubjects and may be useful in future study of other disease states of t he corpus callosum.