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FIG 1. MR venography of the cerebral sinuses and its variations in the torcular herophili.
A, Right and left transverse sinuses are of similar caliber. Both the superior sagittal and straight sinuses drain into the torcular herophili.
B, Flow void is seen in left transverse sinus. The superior sagittal and straight sinuses drain into the right transverse sinus.
C, Right transverse sinus is absent. The right sigmoid sinus and internal jugular vein are atretic. The superior sagittal and straight sinuses drain into the left transverse sinus and then into the sigmoid sinus and left internal jugular vein. Venous plexus are seen around the foramen magnum.
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