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[Evaluation of venous system with 3D-CTA--from the viewpoint of treatment to cerebral aneurysm].

BACKGROUND AND PURPOSE
Recently, many reports have suggested that cerebral aneurysms can be treated under diagnoses based only on the information obtained from three-dimensional CT angiography (3D-CTA). However, these reports have mainly emphasized the excellence of the stereoscopic images of aneurysms and the relationships with the arteries, and almost never discuss the venous information. The present study used 3D-CTA images to evaluate potential problems in the venous system which may affect the pterional approach.


PATIENTS AND TECHNIQUE
This study included 500 sides of 250 patients who underwent screening for cerebrovascular diseases by 3D-CTA. The voxel-transmission method was used for 3D reconstruction. 3D-CTA images in axial stereoscopic views were mainly evaluated, with views in other directions.


RESULTS
The variations of the superficial middle cerebral vein draining the sphenoparietal sinus and cavernous sinus were related to the operative view to assess the potential for venous damage. Potential locations of venous damage to the basal vein include the veins of the first segment draining from the frontal base, the direct communication of the basal vein with the sphenoparietal sinus or cavernous sinus, and the veins of the first segment which independently form the uncal vein draining the sphenoparietal sinus or cavernous sinus.


CONCLUSION
3D-CTA demonstrates the venous system and the spatial relationships with other structures clearly. Such information will help neurosurgeons to construct a better and safer microdissection plan, which will preserve the venous system and help prevent postoperative neurological deficits.