Tiny pituitary lesions can hide. Was your scan dynamic? Did you get a surgeon to read films?
I also had an ocreotide scan. They could test you for neuro endocrine tumors.
Had pet scan nothing there still have high cortisol. What test is there for a tiny pituary tumor that's missed by the MRI? The fatigue is awful.
Usual endocrine issues are not associated with cancer... I did get a pet scan but only after my ACTH skyrocketed where it could have been an ectopic source.
Your doc must have a reason for the test hope all is well.
Post back when you know more.