We evaluated variations of the superficial middle cerebral vein (SMCV) and basal vein of Rosenthal (BVR) by three-dimensional computed tomography angiography (3D-CTA) imaging.
To this end, 3D-CTA images in the axial stereoscopic view and other directions were constructed by the voxel transmission method and maximum intensity projection images were obtained in 600 sides of 300 patients.
The SMCV was classified into 7 courses and drainage pathways, and the BVR into 5 drainage pathways. The drainage pathways of the SMCV were the sphenoparietal sinus or cavernous sinus in 62.8% of sides, the pterygoid plexus in 12.5%, the superior petrosal sinus in 1.5%, the transverse sinus via the middle cranial fossa in 1.8%, the transverse sinus via the temporal squama in 2.2%, and others in 8.2%. The BVR flowed into the great vein of Galen in 87.8% of sides, but the anastomoses between the first and second segments were hypoplastic or aplastic in 37.0% of this type. The deep middle cerebral vein in such cases flowed into the cavernous sinus or sphenoparietal sinus. Therefore, typical BVRs with these anastomoses were present in only 53.3% of sides. More than one-fourth of the typical BVRs also entered the anterior sinuses or veins such as the cavernous sinus. Other outflow patterns were the lateral mesencephalic vein in 5.6%, the peduncular vein in 1.5%, and the lateral or medial tentorial sinus in 5.1%.
Understanding of the embryonal venous drainage pathways is essential to evaluate individual variations in veins. The skull base venous system, which courses medially or laterally and longitudinally, is seen best on axial CT scans. 3D-CTA provides multidirectional stereoscopic images of specific vessels and demonstrates the anatomical relationships with the arteries and the bone structure. Therefore, 3D-CTA is useful for the investigation of individual variations and in preoperative planning for skull base surgery to reduce the invasiveness of surgery.