Patients with suspected endometriosis scheduled for surgery will be identified. They will be asked to participate in a study evaluating the feasibility of FAPI PET-CT in diagnosing endometriosis. The results will be compared with surgical findings, pathology, and other imaging techniques if available (i.e., MRI, US).

This study investigates FAPI PET-CT imaging in endometriosis diagnosis using a standardized protocol. Participants will undergo two imaging sessions after a single FAPI injection:

First Session:

Initial scan at 10 minutes post-injection Follow-up scan at 30 minutes

Second Session:

Additional scans at 60 and 80 minutes post-injection

The protocol is designed to minimize radiation exposure through:

Single FAPI injection Two ultra-low dose CT scans Limited field of view to suspected areas. Nuclear medicine physicians will review PET-CT images independently, blinded to other imaging findings (MRI, US). Results will be shared with surgeons to guide the removal of suspicious lesions during surgery. All removed tissue will undergo pathological examination for confirmation.

The study incorporates safety monitoring:

Observation during and after FAPI administration Follow-up contact at 24-48 hours post-scan Documentation of any adverse events Immediate reporting of unexpected findings. This research could potentially provide evidence for a novel, non-invasive method to comprehensively map endometriotic lesions, improving pre-operative planning.

Inclusion Criteria:

• Female participants aged 18-45 years
• Clinical suspicion of endometriosis based on symptoms
• Scheduled for diagnostic/therapeutic laparoscopic surgery
• Ability to understand and provide written informed consent
• Completed and signed Radiation Exposure Documentation Form

Exclusion Criteria:

• Pregnant women or women who are breastfeeding
• History of pelvic radiation therapy
• Known active malignancy
• Exposure to ionizing radiation for medical purposes within 12 months prior to enrollment

Individual participant data (IPD) that underlie the results reported in published articles will be shared after deidentification. Data will be available beginning 9 months and ending 36 months following article publication. Data will be shared with researchers who provide a methodologically sound scientific proposal. Proposals should be directed to [israels@ziv.gov.il]. Data requestors will need to sign a data access agreement. Data will include deidentified participant data related to FAPI PET-CT findings and surgical/pathological outcomes.

Start: "9 months after publication" End: "36 months following publication"

Qualified researchers can submit a proposal to access de-identified IPD and supporting documents. The proposal should include: research objectives, statistical analysis plan, research team qualifications, and funding source. Upon approval, researchers must sign a data access agreement. Data will be shared via a secure institutional platform.

Open label study. The surgeon operates based on PET-CT findings, and the pathologist examines specimens from lesions detected on PET-CT