Optic chiasm position on MR images.

This article describes the results of a study of the distance from the optic chiasm to the tuberculum sellae as seen on sagittal MR images. Measurements revealed an average chiasm-tuberculum distance of 3.8 mm (2.6 mm for females, 4.3 mm for males) and a sizable group in whom the distance was effectively zero. These results show a fairly close correlation with previous anatomic studies. The closer the chiasm is to the tuberculum, the earlier one may expect clinical manifestations of pituitary disease and the more difficult an intracranial surgical approach to the pituitary will be.