Chuang, Hubert H.

Abstract Objectives Localization of ectopic ACTH‐secreting tumours causing Cushing syndrome (ECS) is essential for clinical management, yet often difficult. [ 68 Ga]‐DOTATATE PET/CT ([ 68 Ga]‐DOTA‐(Tyr 3 )‐octreotate)] is an FDA‐approved high‐resolution diagnostic tool for imaging neuroendocrine tumours. Data on the clinical utility of [ 68 Ga]‐DOTATATE in patients with ECS, however, are scarce. The objectives of this study were to determine the efficacy for ECS localization and the clinical benefit of [ 68 Ga]‐DOTATATE imaging. Method We conducted a retrospective review of all cases with ECS evaluated with [ 68 Ga]‐DOTATATE from November 2016 through October 2018 at three referral centres. The clinical benefit of [ 68 Ga]‐DOTATATE was based on detection of new tumours and resultant changes in management. Results Over the study period, 28 patients with ECS underwent [ 68 Ga]‐DOTATATE: 17 for identification of the primary tumour and 11 during follow‐up. [ 68 Ga]‐DOTATATE identified the suspected primary ECS in 11/17 patients (65%). Of these, nine patients underwent surgery: eight with confirmed ECS (5 bronchial, 1 thymic, 1 pancreatic and 1 metastatic neuroendocrine tumour of unknown primary origin) and one patient with a false‐positive scan (adrenal gland). Of the 11 patients with ECS who underwent [ 68 Ga]‐DOTATATE evaluation during follow‐up, the study led to changes in clinical management in 7/11 (64%) patients. Conclusions [ 68 Ga]‐DOTATATE is sensitive in detecting primary and metastatic ECS, often identifies occult tumours after conventional imaging, and impacts clinical care in the majority of patients.