Evaluation of Positron Emission Tomography (PET) With [18F]FET for the Detection of ACTH-Secreting Corticotroph Pituitary Neuroendocrine Tumors. (PiTFET)

Evaluation of [18F]FET PET for the Detection of ACTH-Secreting Corticotroph Pituitary Neuroendocrine Tumors

Cushing's disease results from adrenocorticotropic hormone (ACTH) secretion by corticotroph pituitary neuroendocrine tumors (PitNETs). Magnetic resonance imaging (MRI) is the reference modality for etiological diagnosis but may to visualize small corticotroph microadenomas in up to 30% of the cases, and false positives may occur.

The study hypothesis is that positron emission tomography (PET) using [18F]fluoroethyl-L-tyrosine ([18F]FET) improves localization of ACTH-secreting corticotroph microadenomas compared with MRI and could inform surgical planning and reduce reliance on invasive inferior petrosal sinus sampling.

This observational cohort (retrospective and prospective data) will assess the diagnostic performance of [18F]FET PET for tumor localization using postoperative histopathology as the gold standard.

Secondary aims include:

1. assessing cases in which PET modifies localization relative to MRI and is correct by gold standard;
2. inter-reader agreement between two nuclear medicine physicians;
3. correlations between PET signal and biochemical markers of hypercortisolism
4. uni- and multivariable analyses of clinical and imaging parameters influencing PET results;
5. association between PET findings and subsequent biological remission.

Study Overview

• Status: Recruiting
• Conditions: Cushing Disease; ACTH-producing Pituitary Tumour
• Intervention / Treatment: Other: Data-only evaluation of [18F]FET PET, pituitary MRI, and biomarkers

• Study Type: Observational
• Enrollment (Estimated): 20

Contacts and Locations

• Study Contact: Name: Anthime FLAUS, MD; Phone Number: +33 4 72 35 69 99; Email: anthime.flaus@chu-lyon.fr

Study Locations

• France
  • Bron, France, 69500
    • Recruiting
    • Hôpital Louis Pradel - Service de Médecine Nucléaire

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Adults treated at a tertiary academic hospital with biochemically confirmed Cushing's disease, evaluated by pituitary MRI and [18F]FET PET as part of diagnostic work-up, and discussed for surgery.

Description

Inclusion Criteria:

• Adults (≥18 years).
• Biochemical diagnosis of Cushing's disease as part of initial management.
• Pituitary MRI performed; if visible, microadenoma <10 mm in diameter.
• Indication for discussion in multidisciplinary tumor board for surgical management.

Exclusion Criteria:

• Minor (age <18 years).
• Macroadenoma of the pituitary.
• ACTH-dependent hypercortisolism secondary to ectopic secretion.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Adults with Cushing's disease evaluated for pituitary surgery; Adults (≥18 years) with biochemically confirmed Cushing's disease with negative or doubtlful or microadenoma on pituitary MRI and are discussed for surgical management; who benefited from a[18F]FET PET in their clinical work-up.	Other: Data-only evaluation of [18F]FET PET, pituitary MRI, and biomarkers; No study-specific procedures. The study evaluates existing [18F]FET PET imaging pituitary MRI, and routine biochemical markers collected as part of standard care.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
[18F]FET PET Performance for Localizing Corticotroph Pituitary Adenomas	Proportion (%) of correct localization of the adenoma by [18F]FET PET, using postoperative histopathological examination of the surgical specimen as the reference standard.	3 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Effect of PET on Tumor Localization Versus MRI	Among cases in which the PET-suggested localization differs from MRI, the proportion (%) in which PET correctly localizes the adenoma (per the primary endpoint definition).	3 months
Inter-Reader Agreement of [18F]FET PET Interpretation	Proportion (%) agreement between the two nuclear medicine physicians' PET interpretations (inter-reader agreement).	1 month
Correlation Between PET SUV and Hypercortisolism Biomarkers	Correlation between [18F]FET PET and biochemical markers	3 months
Determinants of PET Performance (Clinical/Biological/Imaging)	Univariable and multivariable analyses of variables that may influence PET results.	3 months
Prognostic Value of PET Findings for Biological Remission	Correlation between PET results and the patient's biological status at follow-up (biological remission-e.g., corticotroph inertia or normalization of urinary free cortisol (UFC)-versus active hypercortisolism).	3 months

Collaborators and Investigators

• Sponsor: Hospices Civils de Lyon

Study record dates

Study Major Dates

• Study Start (Actual): November 23, 2023
• Primary Completion (Estimated): November 23, 2027
• Study Completion (Estimated): November 23, 2028

Study Registration Dates

• First Submitted: February 2, 2026
• First Submitted That Met QC Criteria: March 10, 2026
• First Posted (Actual): March 11, 2026

Study Record Updates

• Last Update Posted (Actual): March 11, 2026
• Last Update Submitted That Met QC Criteria: March 10, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: MRI; PET; Pituitary; ACTH; Cushing disease; Amino-acid; Corticotroph adenoma; [18F]FET; PitNET
• Additional Relevant MeSH Terms: Endocrine System Diseases; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neoplasms by Site; Neoplasms; Neoplasms by Histologic Type; Endocrine Gland Neoplasms; Neoplasms, Glandular and Epithelial; Adenoma; Hypothalamic Diseases; Hyperpituitarism; Pituitary Neoplasms; ACTH-Secreting Pituitary Adenoma; Pituitary Diseases; Pituitary ACTH Hypersecretion; Biological Factors; Biomarkers
• Other Study ID Numbers: 25-5027

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No