What is the differential on the basis of these images alone? What would you look at to distinguish between them?
The differential is predominantly between a microadenoma and a Rathke cleft cyst. T2 images and delayed T1 post contrast would demonstrate variable signal on T2 (but often not near iso-intense to pituitary) and no delayed enhancement in a Rathke cyst.
A semirounded region of non enhancement is seen standing against the enhancing pituitary gland on these dynamic images.