MR angiography appearance of venous sinuses in the region of the torcular Herophili

Objective: To investigate the anatomic appearance in the region of the torcular Herophili by using MR and to evaluate its clinical significance. Methods: This study involved 123 healthy subjects. All subjects underwent initial T1W and T2W MR examination in order to exclude intracranial occupying disease and vascular malformation. Then, images of venous sinuses were obtained in the region of the torcular Herophili. 72 of these subjects were examined with coronal 2D TOF MR venography (MRV), 44 cases were examined with coronal 3D PC angiography, and other 7 volunteers were examined with both of the two aforementioned methods. Results: (1) The venous drainage dominance showed mainly to the right side in 84 cases, mainly to the left side in 23 cases, equal drainage in 16 cases. (2) According to the relation among the sinuses in the region of the torcular Herophili, all subjects in this study could be grouped into 4 types: Type 1, including those subjects in which a confluence of sinuses existed or the superior sagittal sinus and the straight sinus forked, and the forking of both sinuses joined to form the lateral sinuses. Type 2, including those subjects in which the sagittal sinus drained into one side and the straight sinus drained into the other. Type 3, including those subjects in which the superior sagittal sinus and the straight sinus joined and mainly drained into the right side. Type 4, including those subjects in which the superior sagittal sinus and the straight sinus joined and mainly drained into the left side. Conclusions: MR angiography provides a useful method to show the anatomic features in the region of the torcular Herophili. The pattern of the classification is considered important to assess the venous drainage dominance and helpful to deduce existent and/or potential collateral pathway. These findings may be useful for diagnostic and operative procedure