Fig. 24.10 
Cystic macroadenoma.
 Sagittal T1-weighted MR image (a) showing a large pituitary macroadenoma with suprasellar extension, compressing the optic chiasm. The low signal intensity of the mass is similar to the CSF signal in the lateral ventricles suggesting the predominantly cystic nature of the mass. A coronal CT (b) in the same patient showing the mass to be of low density, like the CSF in the lateral ventricles.