Last updated on February 2019

Evaluation of 68Ga-DOTATATE PET/CT Octreotide and F-DOPA PET Imaging in Patients With Ectopic Cushing Syndrome


Brief description of study

Between 10% and 15% of patients with endogenous hypercortisolism (Cushing syndrome) have ectopic (non-pituitary) production of adrenocorticotropin hormone (ACTH) that causes cortisol excess. In approximately 50% of these patients, the tumoral source of ACTH cannot be found initially despite very detailed and extensive imaging, including studies such as computed tomography, magnetic resonance imaging, and octreotide scan (Octreoscan) using the standard dose of indium-111 pentetreotide ([(111)In-DTPA-D-Phe]-pentetreotide). The sensitivity and specificity of structurally based imaging studies depends on anatomic alterations and the size of the tumor. In contrast, positron emission tomography (PET) and somatostatin ligand (like octreotide) imaging detect pathologic tissue based on physiologic and biochemical processes within the abnormal tissue. This protocol tests the ability of [(18)F]-L-3,4-dihydroxyphenylalanine ((18)F-DOPA) PET, Octreoscan and another somatostatin imaging analogue, (68)Ga-DOTATATE-PET, to localize the source of ectopic ACTH production. The study also examines whether administration of the glucocorticoid antagonist mifepristone can improve the sensitivity of the (68)Ga-DOTATATE PET/CT.

Detailed Study Description

Between 10% and 15% of patients with endogenous hypercortisolism (Cushing syndrome) have ectopic (non-pituitary) production of adrenocorticotropin hormone (ACTH) that causes cortisol excess. In approximately 50% of these patients, the tumoral source of ACTH cannot be found initially despite very detailed and extensive imaging, including studies such as computed tomography, magnetic resonance imaging, and octreotide scan (Octreoscan) using the standard dose of indium-111 pentetreotide ([(111)In-DTPA-D-Phe]-pentetreotide). The sensitivity and specificity of structurally based imaging studies depends on anatomic alterations and the size of the tumor. In contrast, positron emission tomography (PET) and somatostatin ligand (like octreotide) imaging detect pathologic tissue based on physiologic and biochemical processes within the abnormal tissue. This protocol tests the ability of [18F]-L-3,4-dihydroxyphenylalanine (18F-DOPA) PET, Octreoscan and another somatostatin imaging analogue, 68Ga-DOTATATE-PET, to localize the source of ectopic ACTH production. The study also examines whether administration of the glucocorticoid antagonist mifepristone can improve the sensitivity of the 68Ga-DOTATATE PET/CT.

Clinical Study Identifier: NCT02019706

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