Use of [18F] Fluoroethyl-L-tyrosine PET/MRI for Identifying Small Functional Pituitary Adenomas

Who May Qualify: - Patients 18 to 75 years of age with biochemically proven CD, Acromegaly, or tumor hyperprolactinemia as per current Endocrinology guidelines. - Clinical DCE-MRI protocol that is negative or equivocal for identifiable tumor. - Patient willing to have surgery if lesion found, or already scheduled for surgery and lesion identification would be helpful. - Able to provide willing to sign a consent form and be capable of completing the imaging protocols. - Female subjects of childbearing potential (women of childbearing potential \[WOCBP\]) must have a negative urine pregnancy test ≤48 hours prior to the 18F-FET injection. Who Should NOT Join This Trial: - Patients with contraindications to MRI or PET scans. - Patients with known allergies to contrast agents or other imaging-related materials. - Patients with severe medical conditions that preclude participation in the study (e.g. inability to lie supine for 30-60 minutes). - Patients with successful MRI localization of the adenoma. Always talk to your doctor about whether this trial is right for you.