PITUITARY-ADENOMAS WITH INVASION OF THE CAVERNOUS SINUS SPACE - A MAGNETIC-RESONANCE-IMAGING CLASSIFICATION COMPARED WITH SURGICAL FINDINGS

WE PRESENT 25 pituitary adenomas that were confirmed surgically to hav e invaded the cavernous sinus space. The surgical results are compared with the preoperative magnetic resonance imaging findings. For compar able radiological criteria, we classified parasellar growth into five grades. This proposed classification is based on coronal sections of u nenhanced and gadolinium diethylene-triamine-pentaacetic acid enhanced magnetic resonance imaging scans, with the readily detectable interna l carotid artery serving as the radiological landmark. The anatomical, radiological, and surgical conditions of each grade are considered. G rades 0, 1, 2, and 3 are distinguished from each other by a medial tan gent, the intercarotid line-through the cross-sectional centers-and a lateral tangent on the intra- and supracavernous internal carotid arte ries. Grade 0 represents the normal condition, and Grade 4 corresponds to the total encasement of the intracavernous carotid artery. Accordi ng to this classification, surgically proven invasion of the cavernous sinus space was present in all Grade 4 and Grade 3 cases and in all b ut one of the Grade 2 cases; no invasion was present in Grade 0 and Gr ade 1 cases. Therefore, the critical area where invasion of the cavern ous sinus space becomes very likely and can be proven surgically is lo cated between the intercarotid line and the lateral tangent, which is represented by our Grade 2. We also measured tumor growth rates, using the monoclonal antibody KI-67, which shows a statistically higher pro liferation rate (P < 0.001) in adenomas with surgically observed invas ion into the cavernous sinus space, as compared with noninvasive adeno mas.