Normal computed tomography anatomy of the suprasellar subarachnoid space.

To assess normal variants of the suprasellar subarachnoid space, 680 CT scans were reviewed. Three main configurations with subgroups of the suprasellar cistern could be found: a large hexagon (60.7%), a small hexagon (17.6%) and a small tetragon (21.7%). In about a third of the scans, the region of interest was not visualized sufficiently. The large variety of CT appearance of the normal suprasellar space could be attributed to anatomical and technical reasons. To exclude a suprasellar mass lesion it is necessary to be aware of the anatomical variations, investigate the suprasellar region with additional intermediate cuts or contrast enhancement and define the cut level and osseous structures by a lateral skull radiograph.