FET-PET/MRI to locate small hormone-producing pituitary adenomas

Use of [18F] Fluoroethyl-L-tyrosine PET/MRI for Identifying Small Functional Pituitary Adenomas

Phase 1 Interventional Mayo Clinic · NCT07456878

This trial tests whether a special PET/MRI scan called FET-PET/MRI can find small hormone-producing pituitary adenomas in adults whose standard MRI is negative or unclear.

Quick facts

PhasePhase 1
Study typeInterventional
Enrollment5 (estimated)
Ages18 Years to 75 Years
SexAll
SponsorMayo Clinic Academic / other
Locations1 site (Jacksonville, Florida)
Trial IDNCT07456878 on ClinicalTrials.gov

What this trial studies

This Phase 1 protocol uses the investigational PET tracer 18F-fluoroethyl-L-tyrosine (FET) combined with MRI to try to identify small functional pituitary adenomas that are occult or equivocal on clinical dynamic contrast-enhanced MRI. Adults aged 18–75 with biochemically confirmed Cushing disease, acromegaly, or tumor-related hyperprolactinemia and a negative or unclear MRI will undergo FET-PET/MRI. Scans are reviewed for focal tracer uptake and the imaging results are used to inform clinical and surgical decision-making, including whether to proceed with targeted resection. Primary outcomes include diagnostic yield and the degree to which imaging changes management or surgical planning.

Who should consider this trial

Good fit: Adults 18–75 with biochemical confirmation of Cushing disease, acromegaly, or tumor-related hyperprolactinemia whose dynamic contrast MRI is negative or equivocal and who can undergo PET/MRI and are willing to have surgery if a lesion is found.

Not a fit: Patients with successful MRI localization of the adenoma, contraindications to MRI or PET (including pregnancy), or severe medical issues preventing imaging are unlikely to benefit.

Why it matters

Potential benefit: If successful, FET-PET/MRI could help locate tumors that standard MRI misses, enabling more targeted surgery and improved hormone control.

How similar studies have performed: Amino-acid PET tracers have shown promise in small case series for detecting occult pituitary lesions, but use of 18F-FET PET/MRI for this purpose is relatively novel with limited prior data.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Patients 18 to 75 years of age with biochemically proven CD, Acromegaly, or tumor hyperprolactinemia as per current Endocrinology guidelines.
* Clinical DCE-MRI protocol that is negative or equivocal for identifiable tumor.
* Patient willing to have surgery if lesion found, or already scheduled for surgery and lesion identification would be helpful.
* Able to provide informed consent and be capable of completing the imaging protocols.
* Female subjects of childbearing potential (women of childbearing potential \[WOCBP\]) must have a negative urine pregnancy test ≤48 hours prior to the 18F-FET injection.

Exclusion Criteria:

* Patients with contraindications to MRI or PET scans.
* Patients with known allergies to contrast agents or other imaging-related materials.
* Patients with severe medical conditions that preclude participation in the study (e.g. inability to lie supine for 30-60 minutes).
* Patients with successful MRI localization of the adenoma.

Where this trial is running

Jacksonville, Florida

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Pituitary Adenoma
Last reviewed 2026-06-10 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.