Pituitary adenomas with parasellar invasion.

Pituitary adenomas with extension into the parasellar space, the so called "cavernous sinus" can be demonstrated best using MRI. To improve the delineation from the venous compartments the use of unenhanced and enhanced MRI scans is essential. In 25 pituitary adenomas with surgically proven infiltration into the space of the cavernous sinus we correlated the MRI findings with our surgical observations. When the adenoma encases the intracavernous internal carotid artery or reaches as far as to the lateral aspect of the artery, invasion was present in all cases. The critical area where invasion could not be predicted from MRI is the distance between the medial and the lateral aspect of the intracavernous internal carotid artery. By measurement with the monoclonal antibody KI-67 it could be shown, that pituitary adenomas infiltrating the parasellar space have a statistically significant higher growth rate (p less than 0.001), compared to non-invasive adenomas. This is of special interest, because surgical cure becomes unlikely, when invasion into the space of the cavernous sinus is present.