Desmopressin (DDAVP) Stimulation for 18F-FDG-PET Detection of Pituitary Adenoma in Cushing's Disease
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.
• Children: Children age 8 and older are included in this protocol. More than half of the subjects with CD requiring transsphenoidal surgery at the NIH are children. The knowledge gained by the use of DDAVP PET imaging in children with MR-invisible tumors will provide generalizable knowledge in the treatment of CD in this population. Children under the age of 8 usually require anesthesia for a PET scan, which involves greater risk. Therefore, children under the age of 8 will be excluded from participation.
• Pregnant or lactating women: Pregnant and lactating women will be excluded from participation. The PET radiopharmaceutical used in this study can be harmful to a developing fetus. Therefore women who are able to become pregnant will have a pregnancy test performed within 24 hours before PET imaging. Individuals will not be able to participate in PET scanning if the pregnancy test results positive.