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NCT Number: NCT07523997

Imaging of Endometriosis With Total-body PET-CT (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.

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Key information

Conditions

Endometriosis Female Urogenital Diseases Female Urogenital Diseases and Pregnancy Complications Genital Diseases Genital Diseases, Female Urogenital Diseases

Age range

18 year–60 year

Sex eligibility

Female

Study type

Observational

Primary location

Centre for Reproductive Health, Institute for Regeneration and Repair, University of Edinburgh

Edinburgh, City Of Edinburgh, EH16 4UU, United Kingdom

Location status: Recruiting

Location contact

Lucy HR Whitaker, MD

CONTACT

[email protected]

Lucy HR Whitaker, MD

PRINCIPAL_INVESTIGATOR

About this study

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

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

PET/CT

Diagnostic Test

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

PET/MRI

Diagnostic Test

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

Buscopan 20 MG/ML Injectable Solution

Drug

IV injection prior to PET/MRI

Other names: 20mg

Primary outcomes

  1. 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.

Secondary outcomes

  1. 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.

  2. 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.

Study contacts

Contact information is provided by the study sponsor or research team.

Lucy HR Whitaker, MD

CONTACT

[email protected]

01316518321

Sponsors and collaborators

Lead sponsor

University of Edinburgh

Other

Collaborators

  • Life Molecular Imaging Ltd

Registry information

Official study title

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

Acronym: PET-Endo

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Apr 13, 2026
Registry last updated
May 27, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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