Molecular Imaging Agent Shows Promise for Endometriosis Detection and Monitoring

Diagnosing endometriosis remains challenging, particularly for superficial peritoneal endometriosis, the most common subtype, which is often missed on conventional imaging and typically requires laparoscopic surgery for confirmation. These limitations can prolong symptoms, delay treatment, and hinder long-term monitoring. Clinicians also lack reliable tools to assess disease activity and treatment response over time. To help address these gaps, researchers have developed a non-invasive molecular imaging approach designed to visualize lesions and support longitudinal disease assessment.

The Nuffield Department of Women’s & Reproductive Health at the University of Oxford (Oxford, UK), working with Serac Healthcare Limited (London, UK), evaluated 99mTc‑maraciclatide for endometriosis imaging. The agent is a gamma‑emitting radiotracer that binds the αvβ3 integrin, which is upregulated during angiogenesis, a cardinal feature of inflammatory diseases. The findings indicate potential use for diagnosis, disease monitoring, and as a marker of treatment response.

Image:The novel molecular imaging agent shows strong potential for diagnosing and monitoring superficial peritoneal endometriosis, the most common and hardest form to detect (photo courtesy of Adobe Stock)

In the exploratory, open‑label, single‑center Phase 2 DETECT study, 20 individuals with suspected or confirmed pelvic or thoracic endometriosis underwent single‑photon emission computed tomography–computed tomography (SPECT‑CT) after intravenous 99mTc‑maraciclatide. The primary outcome was alignment of radiologic findings with surgical reports among those who completed both imaging and surgery. Imaging was compared with operative lesion type and location to determine concordance.

The scan visualized endometriosis and detected disease missed by conventional imaging. Results were concordant with the surgical presence or absence of disease in 16 of 19 evaluable cases, including visualization in 14 of 17 surgically positive participants and two cases of thoracic involvement. No false positives were reported. The tracer detected lesions across all endometriosis subtypes, was well tolerated, and demonstrated high patient acceptability.

In superficial peritoneal endometriosis—the earliest stage, present in 80% of laparoscopically diagnosed cases—the technique showed particular promise. Among 10 participants with this subtype who had prior transvaginal ultrasound and/or magnetic resonance imaging within 12 months, none of the conventional studies detected superficial peritoneal disease. These observations support further evaluation of 99mTc‑maraciclatide as a non‑invasive diagnostic tool and longitudinal biomarker.

The Phase 2 data were published in The Lancet Obstetrics and Gynaecology. The work was co‑led by the Endometriosis CaRe Centre in Oxford within the Nuffield Department of Women’s & Reproductive Health, with involvement from the National Institute for Health and Care Research Oxford Biomedical Research Centre’s Surgical Innovation Theme. International, multicenter Phase III studies are due to begin later this year.

“The completion and publication of this clinical study marks a pivotal achievement for Serac Healthcare. These data, from a representative patient population, including women receiving hormone therapy, provide evidence of maraciclatide's anticipated real-world performance. With FDA Fast Track Designation and agreed Phase III study designs, we are now advancing to validate these findings in larger trials and progress to regulatory submission,” stated David Hail, CEO of Serac Healthcare.

"These exciting findings indicate that maraciclatide offers a highly promising diagnostic and monitoring tool, particularly for superficial peritoneal endometriosis, which is the most common and yet the hardest type of endometriosis to identify," said Dr. Tatjana Gibbons, lead author on the paper and investigator on the study from the Nuffield Department of Women’s and Reproductive Health, University of Oxford. "We are hugely grateful to the patients who have participated in the DETECT study, without whom investigating this diagnostic approach would not have been possible."

Related Links
Nuffield Department of Women’s & Reproductive Health at the University of Oxford
Serac Healthcare Limited