DDAVP for Pituitary Adenoma

This study is designed as a single institution trial. The study utilizes safe and clinically-validated tools for preoperative workup of patients with small pituitary tumors. DDAVP stimulation and 18F-labeled fluoro-deoxyglucose (FDG) uptake for PET-imaging will be used to detect MRI-negative pituitary adenomas in patients with Cushing s disease. Patients who have MRI-negative pituitary microadenomas will undergo FDG PET-imaging with DDAVP stimulation. Intravenous FDG will be given approximately four hours following DDAVP administration. Within 12 weeks after completion of the FDG high-resolution PET scan, patients will undergo surgical resection of the pituitary adenoma. Surgical and histological confirmation of adenoma location will be noted. All images will be read independently by neuroradiologists blinded to clinical and histopathological outcomes. The diagnostic and localization accuracy of PET-imaging will be assessed by comparing the PET findings with histopathology.