Background: Cushing s disease is caused by a pituitary gland tumor. Patients with Cushing s disease suffer obesity, diabetes, osteoporosis, weakness, and hypertension. The cure is surgery to remove the pituitary tumor. Currently, MRI is the best way to find these tumors. But not all tumors can be seen with an MRI. Researchers hope giving the hormone CRH before a PET scan can help make these tumors more visible. Objective: To test whether giving CRH before a PET scan will help find pituitary gland tumors that might be causing Cushing s disease. Eligibility: People ages 8 and older with Cushing s disease that is caused by a pituitary gland tumor that cannot be reliably seen on MRI Design: Participants will be screened with their medical history, a physical exam, an MRI, and blood tests. Participants will have at least one hospital visit. During their time in the hospital, they will have a physical exam and a neurological exam. They will have a PET scan of the brain. A thin plastic tube will be inserted into an arm vein. A small amount of radioactive sugar and CRH will be injected through the tube. Participants will lie in a darkened room for about an hour and be asked to urinate. Then they will lie inside the scanner for about 40 minutes. After the scan, they will be asked to urinate every 2-3 hours for the rest of the day. Blood will be drawn through a needle in the arm. Participants will have surgery to remove their tumor within 3 months after the scan. Participants will then continue regular follow-up in the clinic.
Study Description: This study is designed as a single institution trial. The study utilizes safe and clinically-validated tools for preoperative workup of subjects with small pituitary tumors. DDAVP stimulation and 18F-labeled fluorodeoxyglucose (FDG) uptake for PET-imaging will be used to detect MRInegative pituitary adenomas in subjects with Cushing s disease. Subjects who have MRI-negative pituitary microadenomas will undergo FDG PETimaging with DDAVP stimulation. Intravenous FDG will be given approximately four hours following DDAVP administration. Within 24 weeks after completion of the FDG high-resolution PET scan, subjects 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. Objectives: Cushing s disease (CD) affects 3,000 people in the United States every year and results in significant morbidity and early mortality. The disease is caused by millimeter sized pituitary microadenomas (corticotropinomas) that secrete adrenocorticotropic hormone (ACTH). Surgical resection of corticotropinomas remains the most effective treatment strategy. Preoperative magnetic resonance imaging (MRI) can detect microadenomas in approximately 50-80% of subjects. Subjects with microadenomas invisible on MR imaging are exposed to more invasive explorations of the sella with fewer instances of hormone remission and higher complications. Corticotropinomas can be detected by FDG positron emission tomography (PET) in 50% of subjects. Prior work by us suggests that secretagogue stimulation with corticotropin-releasing hormone (CRH) leads to increased FDG uptake and improved PET detection of pituitary microadenomas. Since, CRH is no longer available, we will use DDAVP which has a similar biological activity to CRH. If validated, DDAVP-stimulated FDG-PET imaging could provide a complementary imaging modality to improve visualization of ACTH-secreting microadenomas and surgical planning. Primary Objective: The primary objective of this study is to determine the detection rate of MRI-negative pituitary adenomas in subjects with Cushing's disease by DDAVP-stimulated FDG PET imaging. We will analyze whether or not DDAVP-stimulated PET imaging demonstrates tumor in MRI-negative cases by assessing the accuracy and sensitivity of high-resolution FDG PET-imaging detection of ACTH-adenomas that could not be reliably detected on MR-imaging. Secondary Objectives: To assess the accuracy of FDG high-resolution PETimaging localization of ACTH-adenomas in CD compared to surgical and histologic localization. This will be achieved by comparing actual tumor location confirmed by histological findings during surgical resection to the location predicted by PET- and MR-imaging within subjects. Endpoints: Primary Endpoint: The primary outcome measure will be defined as whether or not DDAVP-stimulated PET imaging demonstrates tumor in MRI-negative cases. This will be demonstrated by assessing the accuracy and sensitivity of FDG high-resolution PET-imaging detection of ACTH-adenomas that could not be reliably detected on MR-imaging. Secondary Endpoints: Location of tumor on preoperative PET-imaging and location of tumor during surgery. Histopathological confirmation of ACTH-adenoma will be the gold-standard to measure the primary and secondary endpoints.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
22
Intravenous administration of ovine CRH (Acthrel (Registered Trademark) 1 mcg/kg up to a maximum dose of 100 mcg) results in selective increase in ACTH activity of pituitary adenomas within two minutes and peaks between 10-15 minutes.
National Institutes of Health Clinical Center
Bethesda, Maryland, United States
CRH-stimulated PET imaging demonstrates tumor in MRI-negative cases.
The primary outcome measure will be defined as whether or not CRH- stimulated PET imaging demonstrates tumor in MRI-negative cases. This will be demonstrated by assessing the accuracy and sensitivity of 18F-FDG high-resolution PET-imaging detection of ACTH-adenomas that could not be reliably detected on MR-imaging. Measures will include determining the rate of true tumor detection using PET-imaging compared to histologically-confirmed tumor location.
Time frame: Baseline
Elevation of SUV of 18F-FDG
To measure the elevation of SUV of 18F-FDG within adenomas compared to surrounding normal gland following CRH stimulated PET imaging.
Time frame: Baseline
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