68Ga-DOTATATE PET/CT Imaging for Ectopic Cushing Syndrome

* INCLUSION CRITERIA: To be eligible to participate in this study, an individual must meet all of the following criteria: * 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 * Stated willingness to comply with all study procedures and availability for the duration of the study EXCLUSION CRITERIA: An individual who meets any of the following criteria will be excluded from participation in this study: * 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. * Body weight over 136 kg, which is the limit for the tables used in the scanning areas. * Combined blood withdrawal during the six weeks preceding the study greater than 450 ml. * Subjects who previously underwent ten or more F-DOPA PET/CT scans and ten or more DOTATATE scans.