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 (\[111In-DTPA-D-Phe\]-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 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, and the somatostatin imaging analogue, 68Ga-DOTATATE-PET, to localize the source of ectopic ACTH production.
18 - 90 years of age
Medical history of ectopic Cushing syndrome or diagnosed with the possibility of ectopic Cushing syndrome
For females of reproductive potential: agreement to use highly effective contraception for at least 2 weeks before any PET scan
Ability of subject to understand and the willingness to sign a written informed consent document
Pregnancy or lactation; the radiation associated with PET and CT scans may be harmful to a developing fetus. Likewise the ingestion of radionuclides in breast milk has an unknown risk to an infant.
Evidence of severe active infection
Clinically significantly impaired cardiovascular function, abnormal coagulation in the absence of medically-indicated treatment (PT and PTT elevated by 30% above the normal values), hematopoietic (hematocrit less than 30%, hemoglobin below 10 g/dl, white count below 3000 K/UL, and platelets below 100,000 K/mm^3), hepatic (liver enzymes elevated by 4-fold above normal values), or renal function (plasma creatinine level over 2.1).
Based on the clinical judgment of the attending physician, other medical problems may prompt exclusion.
Single group
DOTATATE PET-CT
Radiation68Ga-DOTATATE PET/CT
F-DOPA PET CT
Radiation68Ga-DOTATATE PET/CT
CT scan
Radiationroutine CT scan
Routine MRI scan
Diagnostic testroutine 1.5 or 3T MRI scan
Gated MRI scan
Diagnostic testCardiac gated MRI scan
68Ga-DOTATATE
Drug68Ga-DOTATATE radioligand
18F-DOPA
Drug18F-DOPA radioligand
To determine which imaging technique (F-DOPA PET/CT, 68Ga-DOTATATE PET/CT, CT, and/or MRI) has the best sensitivity.
Subjects will be imaged every 6-12 months until tumor is found
To determine if there is a combination of imaging tests with optimal diagnostic accuracy.
subjects will be imaged every 6-12 months until tumor is found
To evaluate a potential correlation between 18F-DOPA or 68Ga-DOTATATE uptake and the type of tumor, its size, SSTR expression or proliferative activity.
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