Cerebral MR venography: Normal anatomy and potential diagnostic pitfalls

BACKGROUND AND PURPOSE: MR venography is often used to examine the intracra nial venous system, particularly in the evaluation of dural sinus thrombosi s, The purpose of this study was to evaluate the use of MR venography in th e depiction of the normal intracranial venous anatomy and its variants, to assess its potential pitfalls in the diagnosis of dural venous sinus thromb osis, and to compare the findings,vith those of conventional catheter angio graphy, METHODS: Cerebral MR venograms obtained in 100 persons with normal MR imagi ng studies were reviewed to determine the presence or absence of the dural sinuses and major intracranial veins. RESULTS: Systematic review of the 100 cases revealed transverse sinus flow gaps in 31% of the cases, with 90% of these occurring in the nondominant tr ansverse sinus and 10% in the codominant transverse sinuses. No how gaps oc curred in the dominant transverse sinuses. The superior sagittal and straig ht sinuses were seen in every venogram; the occipital sinus was seen in onl y 10%, The vein of Galen and internal cerebral veins were also seen in ever y case; the basal veins of Rosenthal were present in 91%. CONCLUSIONS: Transverse sinus how gaps can be observed in as many as 31% of patients with normal MR imaging findings; these gaps should not be mistake n for dural sinus thrombosis.