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

This study tests whether a specialized type of PET/MRI scan—using a radioactive tracer called F-18 FET (a marker taken up by active cells)—can find small, hard-to-see tumors in the pituitary gland. Pituitary gland tumors can cause too much production of certain hormones, and sometimes regular MRI scans cannot clearly show where the tumor is located. **You may be eligible if...** - You are between 18 and 75 years old - You have been diagnosed with a pituitary condition causing too much cortisol (Cushing's disease), too much growth hormone (acromegaly), or elevated prolactin due to a tumor - Your standard MRI scan was negative or inconclusive for finding the tumor - You are willing to have surgery if the scan finds the tumor, or you are already scheduled for surgery **You may NOT be eligible if...** - You have a contraindication to MRI or PET scans - You have a known allergy to contrast agents used in imaging - You have severe medical conditions that prevent you from lying still for 30–60 minutes - Your MRI scan already clearly identified the tumor Talk to your doctor to see if this trial is right for you.