title: Conventional and Nuclear Medicine Imaging in Ectopic Cushing's Syndrome: A Systematic Review.
abstract: BACKGROUND
  Ectopic Cushing's Syndrome (ECS) can be a diagnostic challenge with the hormonal source difficult to find. This study analyzes the accuracy of imaging studies in ECS localization.
  
  
  METHODS
  Systematic review of medical literature for ECS case series providing individual patient data on at least one conventional imaging technique (computed tomography [CT]/magnetic resonance imaging) and one of the following: 111In-pentetreotide (OCT), 131I/123I-metaiodobenzylguanidine, 18Ffluoro-2-deoxyglucose-positron emission tomography (FDG-PET), 18F-fluorodopa-PET (F-DOPA-PET), 68Ga- DOTATATE-PET/CT or 68Ga-DOTATOC-PET/CT scan (68Gallium-SSTR-PET/CT).
  
  
  METHODS
  The analysis comprised 231 patients (females, 50.2%; age, 42.617 y). Overall, 52.4%(121/231) had "overt" ECS,18.6% had "occult" ECS, and 29% had "covert" ECS. Tumors were located in the lung (55.3%), mediastinum-thymus (7.9%), pancreas (8.5%), adrenal glands (6.4%), gastrointestinal tract (5.4%), thyroid (3.7%), and other sites (12.8%), and primary tumors were mostly bronchial neuroendocrine tumors (NETs) (54.8%), pancreatic NETs (8%), mediastinum-thymus NETs (6.9%), gastrointestinal NETs (5.3%), pheochromocytoma (6.4%), neuroblastoma (3.2%), and medullary thyroid carcinoma (3.2%). Tumors were localized byCTin66.2%(137/207), magnetic resonance imaging in 51.5% (53/103), OCT in 48.9% (84/172), FDG-PET in 51.7% (46/89), F-DOPAPET in 57.1% (12/21), 131/123I-metaiodobenzylguanidine in 30.8% (4/13), and 68Gallium-SSTRPET/CT in 81.8% (18/22) of cases. Molecular imaging discovered 79.1% (53/67) of tumors unidentified by conventional radiology, with OCT the most commonly used, revealing the tumor in 64%, followed by FDG-PET in 59.4%. F-DOPA-PET was used in only seven covert cases (sensitivity, 85.7%). Notably, 68Gallium-SSTR-PET/CT had 100% sensitivity among covert cases.
  
  
  CONCLUSIONS
  Nuclear medicine improves the sensitivity of conventional radiology when tumor site identification is problematic. OCT offers a good availability/reliability ratio, and FDG-PET was proven useful. 68Gallium-SSTR-PET/CT use was infrequent, despite offering the highest sensitivity.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Isidori
authors.forename: Emilia
authors.initials: E
authors.lastname: Sbardella
authors.forename: Maria Chiara
authors.initials: MC
authors.lastname: Zatelli
authors.forename: Mara
authors.initials: M
authors.lastname: Boschetti
authors.forename: Giovanni
authors.initials: G
authors.lastname: Vitale
authors.forename: Annamaria
authors.initials: A
authors.lastname: Colao
authors.forename: Rosario
authors.initials: R
authors.lastname: Pivonello
mesh_terms: D003480:Cushing Syndrome / Q000175:diagnosis*; D003952:Diagnostic Imaging / Q000379:methods*; D006801:Humans; D009683:Nuclear Medicine; D015203:Reproducibility of Results