The Tentorium in Axial Section. I. Normal CT Appearance and Non-neoplastic Pathology

Abstract

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.

The time course of aneurysmal haemorrhage on computed tomograms

“…These haematomas were usually intraparenchymal (28), sometimes in the cavum septi pellucidi (3 patients with aneurysms of the anterior communicating artery), or extracerebral (1). In 64 other patients CT showed extravasated blood in the basal cisterns or fissures, and in the four remaining cases there was only non-specific evidence of subarachnoid blood in the form of increased density of the tentorium near the hiatus [19]. Until operation, 0028-3940/82/0023/0153/$01.00 Table 1.…”

Computerized Tomography in Dural Sinus Thrombosis

“…Thrombosis of 3s and/or the vein of Galen in contrast to thrombosis of the SSS, should be easily diagnosed as they are well away from bony structures and are in fact surrounded by CSF and brain. This is because the length of the sinus is demonstrated in its entirety in the axial scans that are routinely used (Naidich et al 1977).…”

Author’s reply

“…[2][3][4] The great vein of Galen and straight sinus, as they are surrounded by cenebrospinal fluid and brain, are almost always visualized on CT scan particularly if the study is performed with contrast enhancement, with a quite characteristic appearance. [5] As described by the author, an axial section through the tentonium near its apex with the plane of section slightly inclined to the long axis of the straight sinus would include the great vein of Galen and, more posteriorly, would produce a separate elongated configuration. [5] This hyperdense appearance can be due to the partial volume of straight and sagittal sinuses and also we agree with the author that the subdural hematoma will never or rarely have inverted Y-shaped most posterior end (as also true in the present case- Figure 1, small arrow).…”

“…[5] As described by the author, an axial section through the tentonium near its apex with the plane of section slightly inclined to the long axis of the straight sinus would include the great vein of Galen and, more posteriorly, would produce a separate elongated configuration. [5] This hyperdense appearance can be due to the partial volume of straight and sagittal sinuses and also we agree with the author that the subdural hematoma will never or rarely have inverted Y-shaped most posterior end (as also true in the present case- Figure 1, small arrow). [6] As shown by the author, the outline of the sinus was quite uniform.…”