An observational study in Endometriosis, sponsored by University of Edinburgh. Recruiting at 1 site in United Kingdom. Open to female participants aged 18 Years to 60 Years. Per ClinicalTrials.gov, last updated 2026-05-27.
Sponsored by University of Edinburgh · Observational
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.
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
901 studies on the registry are indexed under Endometriosis; 259 are open to participants now.
This study's planned enrollment of 30 is below the median of 128 across 344 observational studies indexed under Endometriosis.
Browse Endometriosis studies →University of Edinburgh is the lead sponsor of 393 studies on the registry; 64 are open to participants now.
Counted across the registry records on this site, refreshed daily.
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.
Exclusion Criteria:
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 · Diagnostic Test: PET/MRI · Drug: Buscopan 20 MG/ML Injectable Solution
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
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
IV injection prior to PET/MRI
Also known as: 20mg
In vivo uptake of 18F-GP1 and 68Ga-FAPI in endometriosis
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.
Time frame: within 3 months post surgery
Non-invasive in vivo imaging-based characterisation of thrombosis and fibrosis characterisation in superficial, ovarian and deep endometriosis lesions
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.
Time frame: within 3 months post surgery
Acceptability of PET imaging for characterisation of endometriosis
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.
Time frame: within 3 months post surgery
Plan to share: Undecided — 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
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University of Edinburgh