Macroadenoma (Extrasellar Extension) (MRI/CT)	

Extrasellar extension of macroadenoma has important clinical and surgical implications. Suprasellar extension may produce a ‘waist’ due to compression by the diaphragma sellae (Fig. 24. 11). CT best evaluates erosion of the sellar floor and inferior extension into the sphenoid sinus and sphenoid extension is suggested by the appearance of a convex inferior margin of the mass on CT and MR images. However, cavernous sinus extension, particularly when early, is difficult to detect. Unilateral encasement of the carotid artery and distortion of the lateral margins of the cavernous sinus are the most reliable signs (see Fig. 24.11 (b) & (c)). 

Fig. 24.11 Extrasellar extension of macroadenomas. Sagittal T1-weighted MR image (a) showing suprasellar extension with a ‘waist’ caused by the diaphragma sellae. Coronal T1-weighted MR image (b) demonstrating suprasellar and left cavernous sinus extension, encasing the left cavernous carotid artery. Coronal CT image (c) showing suprasellar, cavernous sinus, and sphenoid sinus extension.