The cavenous sinuses are apparently uninvolved. MRI may be useful for evaluating pituitary macro adenomas. Its usefulness in micro adenomas is limited due to spatial resolution and problems with contrast resolution. MR is particularly useful in macro adenomas as it allows assessment of cavernous sinus invasion, carotid artery encasement and involvement of the optic chiasm. CT on the other hand, is better suited to evaluating small tumours and for assessing the presence of sellar-floor erosion.
Pituitary adenomas are usually isointense with and also with normal pituitary gland.
Use of GD-DIPA may allow MR evaluation of smaller lesions.