Midsagittal MR measurements of the corpus callosum in healthy subjects and diseased patients: a prospective survey.

PURPOSE To determine quantitatively a possible corpus callosum (CC) involvement in normal aging and white matter diseases. METHODS Midsagittal size and signal of CC were recorded prospectively from 243 routine MR brain examinations. A midline internal skull surface (MISS) and subcutaneous fat signal intensity were measured to calculate CC/MISS and CC/fat ratios. Four groups of subjects were studied: 124 apparently healthy subjects, 45 patients with multiple sclerosis, 13 patients with a noncerebral cancer under chemotherapy, and 37 AIDS patients. RESULTS Mean surface area of CC in controls was 6.36 cm2. It was significantly larger in men than in women (P < .05), but CC/MISS ratio was not. Elderly controls > 70 years and AIDS patients displayed significant CC atrophy, as well as multiple sclerosis subjects with long-standing disease or with a severe chronic progressive form. CONCLUSION CC substance loss identification should not be based on visual inspection or on absolute area, but by means of a CC/MISS ratio.