Prospective Trial of [18F]AlF-FAPI-74 for PET Imaging of Fibroblast Activation Protein in Patients With Endometriosis

The goal of this clinical trial is to learn whether \[18F\]AlF-FAPI-74 PET/CT can help detect endometriosis in adult women who are already scheduled for laparoscopy due to suspicion of deep infiltrating endometriosis or superficial peritoneal endometriosis. The main aims are: (i) How well does \[18F\]AlF-FAPI-74 PET/CT identify endometriosis lesions compared with findings during laparoscopy? (ii) Can PET/CT identify additional lesions that may not be seen on ultrasound or MRI? (iii) Can ultra-high-resolution NeuroEXPLORER PET/CT improve the detection of small lesions compared with standard PET/CT? Participants will: (i) Receive an intravenous injection of \[18F\]AlF-FAPI-74 followed by a PET/CT scan before their planned laparoscopy. (ii) Undergo their planned laparoscopy, during which PET findings will be compared with the surgical findings and where tissue is removed with laboratory analysis. (iii) Optionally undergo an additional NeuroEXPLORER PET/CT scan after the same tracer injection. (iv) Optionally undergo a second \[18F\]AlF-FAPI-74 PET/CT if participants started gonadotropin-releasing hormone (GnRH) treatment after their first scan to investigate whether tracer uptake in endometriosis lesions changes during treatment.

Inclusion Criteria: * Voluntary written informed consent of the participant has been obtained prior to any screening procedures. * At least 18 years of age at the time of signing the Informed Consent Form (ICF). * At least one of the following to be eligible for the DE cohort: (i) Clinical suspicion of DE, defined as the presence of deep nodule(s) during vaginal examination determined by a clinician who is an expert in endometriosis. (ii) Diagnostic suspicion of DE, defined as an ultrasound and/or MRI that shows lesions suspicious for DE. * At least one of the following to be eligible for the SPE cohort: (i) Clinical suspicion of SPE, defined as clinical symptoms suspicious of SPE determined by a clinician who is an expert in endometriosis. These clinical symptoms include dysmenorrhea, deep dyspareunia, dysuria, dyschezia, painful rectal bleeding or haematuria, shoulder tip pain, catamenial pneumothorax, cyclical cough/haemoptysis/chest pain, cyclical scar swelling and pain, fatigue, and infertility. (ii) Diagnostic suspicion of SPE, defined as an ultrasound and/or MRI that shows lesions suspicious for SPE. * Planned laparoscopy for suspected endometriosis. Exclusion Criteria: * For SPE cohort: (i) Ultrasound and/or MRI with lesions suspicious of ovarian endometriosis and/or DE. (ii) Clinical symptoms suspicious of ovarian endometriosis and/or DE, determined by a clinician who is an expert in endometriosis. * Prior abdominal surgery less than one year ago. * Female who is pregnant, breastfeeding or is of childbearing potential and not using an adequate, highly effective contraceptive or no usage of contraception when sexually active are not accepted. * Participant is mentally or legally incapacitated, does not understand the study design or is not willing or capable to undergo all study-specific procedures. * Any disorder or condition, which in the Investigator's opinion might jeopardise the participant's safety or compliance with the protocol, or may influence the result of the study. * Any prior or concomitant treatment(s) that might jeopardise the participant's safety or that would compromise the integrity of the Trial. * Participation in an interventional Trial with an investigational medicinal product (IMP) or device when the trial designs are not considered compatible by the study team. * Participation in a clinical scientific study in the last 12 months with a radiation exposure caused by the experimental procedures greater than 1 mSv. * Participant has a known hypersensitivity to \[18F\]AlF-FAPI-74 or the used excipients.