Imaging of Endometriosis With Total-body PET-CT (PET-Endo) (PET-Endo)

May 22, 2026 updated by: University of Edinburgh

Novel Non-invasive Imaging of Endometriosis Using Total-body PET-CT Programme (PET-Endo)

Endometriosis is a disease that affects 1 in 10 women and is associated with debilitating pain and infertility. Endometriosis is where cells similar to those lining the womb (the 'endometrium') grow elsewhere in the body, forming 'lesions'. Most commonly the lesions grow on the lining of the pelvic cavity, called 'peritoneal' endometriosis. Lesions can also grow on the ovary, this is called 'ovarian' endometriosis, or form nodules, called 'deep' endometriosis.

At present the only way to confidently identify endometriosis is through surgery, this exposes patient to the risks of surgery and contributes to the diagnostic delay associated with endometriosis.

PET/CT is a specialist scan that is commonly used to identify cancers which cannot be seen on other types of scans. PET/CT uses a 'tracer', a substance given into a vein which then temporarily accumulates in areas of disease.

This project will determine if a new specialist scan, total body PET/CT, and novel tracers that were developed for other conditions can be used to identify some of the key pathways in endometriosis: bleeding and scarring. Being able to identify these processes in endometriosis lesions and being able to track how they change over time would improve our understanding of endometriosis. The investigators also want to know if these pathways are different between superficial, deep and ovarian endometriosis, and what the impact is of the hormones related to the menstrual cycle.

In this study up to 30 people who have suspected endometriosis and are already due to undergo diagnostic surgery will be asked to undergo two total-body PET/CT scans in Edinburgh, one at one visit and one another visit. Participants will also have a PET/MRI scan at visit. Participants will have a different tracer at each visit. The investigators will then compare the scan findings with their subsequent surgical findings.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

This will be an observational cohort study using a prospectively recruited cohorts for both cross-sectional and longitudinal comparison across the spectrum of endometriosis subtypes.

Up to 30 participants with a clinical/radiological diagnosis of likely endometriosis and due to undergo confirmatory laparoscopy in the subsequent four months will be recruited.

Data collected at baseline includes demographics, clinical history including previous imaging. Participants will complete the WERF EPHect questionnaire

Participants will attend two visits for imaging. They will undergo advanced imaging by total-body positron emission tomography and computed tomography (PET/CT), followed by PET/MRI for anatomical reconciliation of lesions and additional information about tracer dynamics. At one visit 68Ga-FAPI will be administered, and at the other 18F-GP1. IV buscopan will be given prior to the PET/MRI.

Following completion of imaging studies, participants will be invited to complete an online acceptability questionnaire, and complete and optional qualitative interview about their experience.

Subsequent surgical findings and associated histopathology will be correlated with tracer uptake

Study Type

Observational

Enrollment (Estimated)

30

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Lucy HR Whitaker, MD
  • Phone Number: 01316518321
  • Email: ETMT@ed.ac.uk

Study Locations

  • United Kingdom
    • City Of Edinburgh
      • Edinburgh, City Of Edinburgh, United Kingdom, EH16 4UU
        • Recruiting
        • Centre for Reproductive Health, Institute for Regeneration and Repair, University of Edinburgh
        • Contact:
        • Principal Investigator:
          • Lucy HR Whitaker, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

30 patients in NHS Lothian with clinically diagnosed endometriosis due to undergo confirmatory laparoscopy in the subsequent four months will be recruited. All subjects recruited for the study will be able to withdraw from the study at any time. The patients will be referred to the study by their treating physicians to investigate clinically diagnosed endometriosis. We will not recruit or enroll healthy volunteers in this study.

Description

Inclusion Criteria:

  • Chronic pelvic pain
  • Clinical/radiological diagnosis of likely endometriosis and due to undergo confirmatory laparoscopy in the subsequent four months

Exclusion Criteria:

  • Inability or unwilling to give informed consent
  • Actively trying to conceive, pregnant or breastfeeding
  • Post menopausal (no periods for >12 months and not taking hormonal treatments to prevent periods or bilateral oophorectomy performed)
  • Previous hysterectomy
  • Confirmed or suspected pelvic malignancy
  • Contraindication to MRI (ferromagnetic material in the body, metallic device implantation or claustrophobia)
  • Contraindication to buscopan (e.g. glaucoma, unstable cardiac disease, arrythmias, myasthenia, previous hypersensitivity to buscopan)
  • Taking part in a CTIMP or interventional non-CTIMP study
  • Previous severe pelvic inflammatory disease
  • Previous peritonitis

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Suspected endometriosis
Women/those assigned female at birth (aged ≥18 years) with chronic pelvic pain and a clinical/radiological diagnosis of likely endometriosis and due to undergo confirmatory laparoscopy in the subsequent four months.
Diagnostic test: PET/CT
Hybrid positron emission tomography and computed tomography will be performed after intravenous administration of the 68Ga-FAPI or the 18F-GP1 radiotracer and images centred on the pelvis. Attenuation-correction CT will be performed before acquisition of PET data
Diagnostic test: PET/MRI
Hybrid PET/MRI will be performed on a 3T scanner with T1 mapping immediately after the PET/CT with images acquired centred on the pelvis after injection of buscopan
Drug: Buscopan 20 MG/ML Injectable Solution
IV injection prior to PET/MRI
Other Names:
  • 20mg

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
In vivo uptake of 18F-GP1 and 68Ga-FAPI in endometriosis
Time Frame: within 3 months post surgery
Tracer uptake will be quantified by determining standardized uptake values (SUVs) and tissue to background ratio (TBR) in areas of increased uptake within the abdomen. This will correlated with surgical findings, specifically presence and location of endometriosis lesions.
within 3 months post surgery

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Non-invasive in vivo imaging-based characterisation of thrombosis and fibrosis characterisation in superficial, ovarian and deep endometriosis lesions
Time Frame: within 3 months post surgery

Tracer uptake will be quantified by determining standardized uptake values (SUVs) and tissue to background ratio (TBR) in areas of increased uptake within the abdomen.

The relative values for the two separate tracers GP1 (activated platelets) and FAPI (fibrosis) will be correlated with the macroscopic appearance of lesions of differing subtypes at surgery.
within 3 months post surgery
Acceptability of PET imaging for characterisation of endometriosis
Time Frame: within 3 months post surgery
Bespoke acceptability questionnaire will be administered following surgery. Acceptability of the overall study and specific aspects will be rated on a 5 point Likert scale, with free text options for further detail. Data will summarised despitative, with thematic analysis of free text where able. Additional acceptability data will be derived from qualitative interviews of a purposive sample of participants and analysed thematically.
within 3 months post surgery

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Edinburgh

Collaborators

Life Molecular Imaging Ltd

Investigators

  • Principal Investigator: Lucy HR Whitaker, MD, University of Edinburgh

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

April 8, 2026

Primary Completion (Estimated)

April 1, 2027

Study Completion (Estimated)

December 31, 2027

Study Registration Dates

First Submitted

April 2, 2026

First Submitted That Met QC Criteria

April 9, 2026

First Posted (Actual)

April 13, 2026

Study Record Updates

Last Update Posted (Actual)

May 27, 2026

Last Update Submitted That Met QC Criteria

May 22, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • AC24225
  • MRC/IAA/017 (Other Grant/Funding Number: MRC IAA)
  • UKRI3897 (Other Grant/Funding Number: UKRI)
  • EPD/24/19 (Other Grant/Funding Number: Chief Scientist Office)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

IPD Plan Description

Requests for anonymised data sharing will be considered on a case by case basis by the trial management team with appropriate data sharing contracts in place

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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