Dynamic CT of the laterosellar extradural venous spaces.

We evaluated the ability of dynamic CT scanning to accurately demonstrate the laterosellar extradural venous spaces. Careful examination of 680 consecutive patients with this technique has permitted us to describe four main venous groups: the veins of the lateral wall (present in 98% of cases), the vein of the inferolateral group located beneath cranial nerve VI (present in 92% of cases), the medial vein located between the internal carotid artery and the pituitary gland (present in 20-30% of cases), and the vein of the carotid sulcus located between the intracavernous internal carotid artery and the lateral wall of the sphenoid bone (present in 65% of cases). The vein of the carotid sulcus is absent only when the internal carotid artery lies close to the sphenoid bone. In 12 patients with suspected cavernous sinus invasion, dynamic CT scanning demonstrated obliteration of the vein of the carotid sulcus. In five patients with huge tumors of the temporal region, dynamic CT scanning of the cavernous sinus permitted demonstration of normal laterosellar extradural venous spaces, thus permitting exclusion of intracavernous sinus invasion. We believe dynamic CT is the imaging technique best suited for studying the laterosellar extradural venous spaces. Its spatial resolution and dynamic capacity make it superior to MR, and it should be the first procedure when invasion of the cavernous sinus by a pituitary tumor is suspected.