Cavernous sinus invasion by pituitary adenoma: MR imaging.

PURPOSE To define magnetic resonance (MR) imaging criteria for the diagnosis of cavernous sinus invasion by pituitary adenoma. MATERIALS AND METHODS The MR images obtained in 106 patients (86 female, 20 male; age range, 16-71 years) were reviewed retrospectively by two physicians. The standard-of-reference criteria for invasion were the surgical findings. A chi(2) analysis was performed, and the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for nine groups of MR imaging signs were computed. RESULTS Invasion of the cavernous sinus was certain (PPV, 100%) if the percentage of encasement of the internal carotid artery (ICA) by tumor was 67% or greater. It was highly probable if the carotid sulcus venous compartment was not depicted (PPV, 95%) or the line joining the lateral wall of the intracavernous and supracavernous ICAs was passed by the tumor (PPV, 85%). It was definitely not invaded (NPV, 100%) if the percentage of encasement of the intracavernous ICA was lower than 25% or the line joining the medial wall of the intracavernous and supracavernous ICAs was not passed by the tumor. CONCLUSION The radiologic diagnosis of cavernous sinus invasion by pituitary adenoma remains difficult, but the above-mentioned criteria may be of assistance.