Venous sinus thrombosis: A misdiagnosis using MR angiography

Introduction: Magnetic resonance venography (MRV) is a non-invasive imaging modality that is used in many centers to supplant conventional cerebral digital subtraction angiography (DSA) for the diagnosis of dural venous sinus thrombosis. Discussion: We present the case of a pregnant female diagnosed with dural venous sinus thrombosis by serial time-of-flight (TOF) MRV examinations, and treated with long-term anticoagulation based on these examinations. Results: The appearance of the affected dural sinus did not change on MRV over the treatment period. The patient returned during follow-up with new-onset pulsatile tinnitus, which prompted us to perform DSA to exclude a dural arteriovenous fistula. DSA revealed that the segment of venous sinus diagnosed as thrombosed on MRV actually was patent but had a septation in its midsection. Conclusions: We concluded that the patient did not have a venous sinus thrombosis at the time of MRV examinations but rather an anatomical variant mimicking a thrombosis, which would not have required any treatment. MRV, particularly TOF MRV, is limited by artifacts in correctly identifying vascular anatomy and pathology and should be interpreted carefully. DSA remains the reference standard for most vascular imaging.