Intracranial MR venography in children: normal anatomy and variations.

BACKGROUND AND PURPOSE Little information is available regarding the anatomy of the intracranial veins and sinuses that can be shown on MR venograms of children. The aim of this study was to determine the normal venous anatomy and anatomic variants. METHODS Fifty children who were referred for investigation of developmental delay and who had normal results of MR imaging of the brain were recruited into the study. The cerebral veins and sinuses, including the occipital sinuses, were assessed by using 2D time-of-flight venography. Particular attention was paid to the anatomy of the venous confluence. RESULTS Twenty-seven cases had dominant right transverse sinuses, 18 had dominant left transverse sinuses, four had co-dominant transverse sinuses, and one had absence of both transverse sinuses. In 21 (51%) of 41 cases without occipital sinuses, absent or hypoplastic transverse sinuses were found. Nine patients had occipital sinuses. Five (56%) of nine patients with occipital sinuses were younger than 2 years, and patients younger than 2 years accounted for 24% of all patients (12 of 50 patients) in the study. In six (67%) of nine patients with occipital sinuses, absent or hypoplastic transverse sinuses were shown. Two patients had bulbous prominence of the vein of Galen. One had foreshortened superior sagittal sinus, which in turn is drained by two paramedian cortical veins. CONCLUSION Understanding the normal anatomy of the cerebral venous system and its variants by using MR venography in children provided the background to future studies on anomalous venous structure in malformations of the brain.