The tentorium in axial section. I. Normal CT appearance and non-neoplastic pathology.

Bands of increased density representing the free edges and lateral margins of the tentorium were routinely identified on 100 sequential, normal, contrast-enhanced axial CT scans of good quality. Because the tentorium has a complex shape, the exact configuration of these bands varies with the level and the angle of the CT section. Comparison of CT scans with anatomic specimens permits an understanding of these varying configurations, and provides a means to estimate the position of the tentorium on non-contrast CT studies. The CT manifestations of diverse non-neoplastic diseases including subarachnoid hemorrhage, arteriovenous malformation, venous sinus thrombosis and Dandy-Walker malformation may be understood, in part, in terms of the configuration and density of these tentorial bands.