"Bifurcated superior sagittal sinus draining directly into each transverse sinus without forming the torcular Herophili. This is a normal anatomical variant 3 that creates a "pseudo-empty delta sign" 4,5 on venography."
"Caution must be taken to achieve a well-timed acquisition in CT cerebral venography, particularly in cases of intracranial hypertension which can cause delayed filling of the venous sinus. A premature acquisition may create a false impression of thrombosis, which is simply due to contrast not yet reaching the venous sinuses. The cerebral veins should also be opacified on a CT cerebral venogram; if they are not, one should suspect premature acquisition."