MRI diagnosis of cavernous sinus invasion by pituitary adenomas

Several MRI signs are helpful for the preoperative MRI diagnosis of caverno us sinus invasion by an adenoma. The first step is to analyse the percentag e of encasement of the intracavernous ICA by the adenoma. If this percentag e is greater than or equal to 66 %, the cavernous sinus is invaded. If the percentage of encasement of intracavernous ICA is less than 25 %, the caver nous sinus is not invaded. If the percentage of encasement is between 25 an d 66 %, the analysis of the cavernous venous compartment, the drawing of in tercarotid lines and the analysis of the shape and venous compartments of t he cavernous sinus are necessary. The cavernous sinus invasion remains very likely if the carotid sulcus venous compartment is obliterated, or if the lateral intercarotid line is crossed. Conversely, if the median intercaroti d line is uncrossed, the superior venous compartment is visible, the cavern ous sinus is of normal size, or there is no bulging of its lateral dural wa il, invasion of the cavernous sinus space can reliably be excluded.