14 January 2011

Cerebral Venous Sinus Thrombosis

Native CT (without contrast) shows increased density in the right sigmoid sinus and transverse sinus. Those are not characteristic findings since also high RBC count can cause hyperdense sinus. However in this case note difference in density when compared with the normal left side. This is a sign that should raise suspicion of Cerebral Venous Sinus Thrombosis.
Finding of Cerebral Venous Sinus Thrombosis is confirmed with CT Cerebral Venography that is performed 45 seconds after contrast injection. Above images show lack of contrast in the right sigmoid sinus (arrows) that is known as "empty delta sign". Also note large thrombus in the right transverse sinus (arrow heads). The "empty delta sign" mostly refers to lack of contrast in the confluence of sinuses but in this case it is the same principle and same empty delta in the sigmoid sinus.
Most important take home message is to adjust the window and level on the native series and compare both sides for any asymmetry. In case of clinical suspect Cerebral Venous Sinus Thrombosis include CT Cerebral Venography in your investigation.