Case 9 - Mimics of dural venous sinus thrombosis

Summary

Imaging description

Evaluation for cerebral dural venous sinus thrombosis is generally undertaken with one of many imaging modalities: MRI, non-contrast CT, time-of-flight MR venography (TOF MRV), contrast-enhanced MRV and CT venography.

Absence of blood flow secondary to sinus aplasia or hypoplasia can be confused with venous sinus thrombosis on non-contrast CT of the brain. Sinus hypoplasia or atresia is one of the most common anatomic variations of the dural venous sinuses. In most patients, the right transverse sinus is larger than the left [1]. Studies using conventional TOF MRV have shown the left transverse sinus to be atretic or severely hypoplastic in 20–39% of people, with the medial aspect of the left transverse sinus being the most significantly affected (Figure 9.1). When transverse sinus hypoplasia or aplasia is found, the ipsilateral sigmoid and jugular sinuses are usually also hypoplastic or aplastic [2].

Clues that suggest an etiology other than sinus hypoplasia or aplasia include:

• Secondary signs of thrombosis or injury e.g. cerebral infarct, edema or hemorrhage (Figure 9.2)

• Collateral vessel filling or recanalization

• Intrinsic high T1 signal within a dural sinus, which suggests thrombosis (Figure 9.3).