In 1993 Engelbert Knosp et al. offered the Knosp grade system for showing invasion of cavernous sinus by pituitary macroadenoma. Briefly, the much laterally adenoma grows and surrounds the internal carotid artery (ICA), the more grade level is. The grading defined by the relation of carotid lines with the limits of invasion. These lines passes through supra- and intracavernous internal carotid artery in coronal view. There are medial, median and lateral carotid lines 1).