Neuroradiology

Empty delta sign

descriptive term indicating the CT appearance of the thrombosed superior sagittal sinus (see venous occlusive disease) following contrast injection, when sliced in the axial plane. The lumen of the triangular ("delta-shaped") sinus appears relatively hypointense ("empty") with respect to the enhanced dural wall.

MRI shows a similar picture, but the signal of coagulated blood varies according to the age of the thrombus.

SG