[68Ga]Ga-DOTATATE PET/CT and PET/MR enhances the detection of pituitary ACTH-secreting adenomas in cushing’s disease

Introduction This study aimed to evaluate the diagnostic performance of [ 68 Ga]Ga-DOTATATE PET/CT or PET/MR in comparison to dynamic MR (dMR) in locating ACTH-secreting pituitary adenomas in Cushing's disease (CD). The utility of PET and MR semi-quantitative parameters was additionally explored as non-invasive biomarkers for tumor characterization. Methods Aretrospective analysis was conducted in 14 patients with CD and 16 controls with ectopic ACTH syndrome. Surgical pathology and post-operative follow-up served as reference standard. All patients underwent [ 68 Ga]Ga-DOTATATE PET/CT or PET/MR, dMR; some also underwent [ 18 F]F-FDG PET. Imaging interpretation included visual and semi-quantitative (SUVmax and ADCmin) assessment. Results [ 68 Ga]Ga-DOTATATE PET demonstrated a 100% sensitivity indetecting ACTH-secreting pituitary adenomas, superior to dMR with a sensitivity of 85.7%. [ 18 F]F-FDG PET showed a sensitivity of 80%. Combining [ 68 Ga]Ga-DOTATATE PET with functional tests (high dose dexamethasone-suppression test and/or inferior petrosal sinus sampling) achieved specificity up to 100%, whereas the specificity of PET alone was only 50% due to pituitary structural abnormalities. Semi-quantitative analysis confirmed significantly reduced [ 68 Ga]Ga-DOTATATE SUVmax and ADCmin in adenomas. Diagnostic efficacy ranked as follows: G-SUVmax from PET/MR was optimal (AUC1.0), followed by ADCmin (AUC 0.96) and G-SUVmax from PET/CT (AUC 0.87). Discussion G-SUVmax and ADCmin can be used as reliable diagnostic predictors. [ 68 Ga]Ga-DOTATATE PET/MR may facilitate the preoperative localization of CD.