An interventional study of [18F]FET PET-MRI in Cushing Disease, sponsored by University Hospital, Basel, Switzerland. Enrolling by invitation at 2 sites in 2 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-06.
Sponsored by University Hospital, Basel, Switzerland · Not applicable, Interventional, and Diagnostic
In ACTH-dependent hypercortisolism it is important to distinguish between Cushing's disease (CD), with ACTH production by a pituitary neuroendocrine tumour (PitNET) and Cushing's syndrome (CS), with ectopic ACTH production. Bilateral inferior petrosal sinus sampling (IPSS) is the gold standard for this distinction, with a diagnostic accuracy of 98%. However, IPSS is an invasive procedure and an indi-rect diagnostic method, rarely providing reliable data on the exact location of the PitNET. This has a major impact on the therapeutic approach, short and long-term remission rates, and other outcomes. Hybrid Positron-emission tomography-Magnetic Resonance Imaging (PET-MRI) using O-(2-[18F]-fluo-roethyl)-L-tyrosine ([18F]FET) is promising in this respect. Recent data published by our research group demonstrate a a sensitivity of 100% a high accuracy in in the precise localization of ACTH-secreting PitNETs. We hypothesize that [18F]FET PET-MRI could become the new non-invasive diagnostic stand-ard, but data regarding a direct comparison between the diagnostic impact of [18F]FET PET-MRI versus IPSS in the differentiation between CD and ectopic CS are lacking. In addition, there are currently no other reliable biomarkers to distinguish the two disorders. The investigators hypothesize that the ACTH-dependent biomarker copeptin could be a valuable addition in this regard. The aim of this prospective diagnostic study is to compare the diagnostic accuracy of [18F]FET-PET-MRI and IPSS in differentiating CD from ectopic CS in patients with ACTH-dependent hypercortisolism.
Exclusion Criteria:
Participants will undergo both \[18F\]FET-PET-MRI and inferior petrosal sinus sampling (IPSS) to evaluate their diagnostic performance in differentiating Cushing's disease from ectopic ACTH secretion. Results of both procedures will be made available to the treating medical team and participants as they become available.
Diagnostic Test: [18F]FET PET-MRI
All participants will undergo both \[18F\]fluoroethyltyrosine positron emission tomography-magnetic resonance imaging (\[18F\]FET-PET-MRI) and inferior petrosal sinus sampling (IPSS) as part of the diagnostic work-up for ACTH-dependent hypercortisolism. The purpose is to compare the diagnostic accuracy of these two modalities in distinguishing Cushing's disease from ectopic ACTH secretion. The results from both diagnostic tests will be communicated to the treating medical team and the participant to guide further clinical management.
Comparison of the proportion of correct distinctions between CD and ectopic CS in patients with ACTH-dependent hypercortisolism using [18F]FET PET-MRI versus IPSS
The difference in the proportion of correct distinction between CD and ectopic CS in patients with ACTH-dependent hypercortisolism using \[18F\]FET PET-MRI versus IPSS
Time frame: Patients will receive standard surgical or radiotherapeutic treatment. The study will collect follow-up data 3-6 months post-treatment without influencing clinical management or requiring study-specific visits.
Copeptin values during IPSS
Best fit of diagnostic copeptin values for differentiation between CD and ectopic CS with the inferior petrosal sinus sampling (IPSS) after desmopressin injection,
Time frame: During the IPSS
ACTH values during IPSS
Best fit of diagnostic ACTH values for differentiation between CD and ectopic CS with the inferior petrosal sinus sampling (IPSS) after desmopressin injection
Time frame: During the IPSS
Comparison of the diagnostic accuracy between [18F]FET PET-MRI and IPSS for differentiating between CD and ectopic CS in patients with ACTH-dependent hy-percortisolism
ROC AUC of the \[18F\]FET PET-MRI and IPSS in differentiating CD from ectopic CS Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the \[18F\]FET PET-MRI and IPSS for differentiation between CD and ectopic CS
Time frame: Follow-up data 3-6 months post-treatment
Exact localization of small functional PitNETs in patients with CD using the [18F]FET PET-MRI
Stated as left, central or right side, assessed by an experienced nuclear medicine physician and neuroradiologist Sensitivity, specificity, PPV and NPV of the \[18F\]FET PET-MRI for the exact localization of small functional PitNETs in patients with CD
Time frame: perioperative
Exact localization of small functional PitNETs in patients with CD using the inferior petrosal sinus sampling (IPSS)
Sensitivity, specificity, PPV and NPV of the IPSS for the exact localization of small functional PitNETs in patients with CD
Time frame: perioperative
Exact localization of small functional PitNETs in patients with CD using the structural MRI
Sensitivity, specificity, PPV and NPV of the structural MRI for the exact localization of small functional PitNETs in patients with CD
Time frame: perioperative
Plan to share: No
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Pituitary ACTH Hypersecretion→
University Hospital, Basel, Switzerland