The earliest form remains nearly invisible to standard imaging
For generations, endometriosis has hidden behind the limits of conventional medicine, forcing millions of women to choose between unresolved suffering and invasive surgery before receiving a diagnosis. Researchers at Oxford University have now published Phase 2 evidence that a radiotracer imaging agent — 99mTc-maraciclatide — can illuminate the disease's biological signature non-invasively, detecting lesions that ultrasound and MRI routinely miss. The findings, published in The Lancet Obstetrics and Gynaecology, represent a quiet but consequential shift in how medicine might finally see what it has long overlooked.
- Endometriosis affects millions of women worldwide, yet its most common form — superficial peritoneal disease — is effectively invisible to standard imaging, leaving patients trapped in diagnostic limbo for years.
- The Oxford DETECT study found that 99mTc-maraciclatide correctly identified endometriosis in 14 of 17 surgically confirmed cases, with zero false positives — a precision that conventional scans have never achieved for this disease.
- The tracer works by binding to a protein activated during new blood vessel formation, making active lesions visible on SPECT-CT scans and catching even rare thoracic endometriosis that standard tools routinely miss.
- The study was small and single-centre, meaning its promise remains conditional — Phase 3 international trials launching this year will determine whether these results hold across diverse patient populations.
- With FDA Fast Track Designation already secured, the path from research to clinical availability is accelerating, offering women who have spent years seeking answers a realistic horizon for change.
For millions of women, endometriosis is not just a medical condition — it is a years-long ordeal of pain, misdiagnosis, and the eventual surrender to invasive surgery before anyone confirms what is wrong. The disease, caused by tissue similar to the uterine lining growing outside the uterus, produces inflammation, scarring, and infertility, yet remains stubbornly hidden from conventional imaging. Researchers at Oxford's Nuffield Department of Women's & Reproductive Health, working with Serac Healthcare, have now published Phase 2 data pointing toward a way out of that diagnostic trap.
The tool is a radiotracer called 99mTc-maraciclatide, which binds to a protein that surges during angiogenesis — the formation of new blood vessels that marks active inflammatory disease. Injected intravenously and scanned with a SPECT-CT camera, it reveals where endometriosis is active in the body. In the DETECT study, 20 patients with suspected or confirmed endometriosis underwent the scan before surgery. The imaging correctly predicted disease presence or absence in 16 of 19 completed cases, detected endometriosis in 14 of 17 surgically confirmed patients, and produced no false positives. It also identified two cases of thoracic endometriosis — a rare variant that conventional imaging routinely misses.
The most striking finding involved superficial peritoneal endometriosis, the earliest and most common form of the disease, accounting for roughly 80 percent of laparoscopically diagnosed cases. Ten study participants had undergone ultrasound or MRI within the previous year — none of those scans had found anything. The maraciclatide imaging found it in all of them, offering the first non-invasive window into the disease at its most elusive stage.
Lead author Dr. Tatjana Gibbons described the results as a potential turning point for women whose symptoms have long been dismissed. Professor Christian Becker of Oxford's Endometriosis CaRe Centre noted that without reliable imaging tools, women have historically faced a stark choice between uncertainty and surgery. Phase 3 multi-centre international trials are set to begin later this year, with FDA Fast Track Designation already granted. If those results confirm what Oxford has found, maraciclatide could reach clinical availability within a few years — and for women who have spent a long time waiting to be believed, that represents something close to hope.
For millions of women, endometriosis arrives as a diagnosis only after months or years of pain, failed treatments, and invasive surgery. The condition—tissue similar to the uterine lining growing outside the uterus—causes inflammation, scarring, and infertility, yet remains stubbornly difficult to identify without putting a patient under anesthesia and threading a camera into her abdomen. Now researchers at Oxford's Nuffield Department of Women's & Reproductive Health, working with the company Serac Healthcare, have published Phase 2 data suggesting a way out of that diagnostic trap.
The tool is a radiotracer called 99mTc-maraciclatide, a molecular imaging agent that lights up the biological signature of endometriosis. The tracer binds to a protein called αvβ3 integrin, which surges during angiogenesis—the formation of new blood vessels—a hallmark of inflammatory disease. When injected intravenously and scanned with a SPECT-CT camera, the agent reveals where endometriosis is active in the body. The findings, published in The Lancet Obstetrics and Gynaecology, suggest the scan could replace or at least delay the need for laparoscopic surgery, the current gold standard for definitive diagnosis.
The DETECT study enrolled 20 patients with suspected or confirmed pelvic or thoracic endometriosis. Researchers performed the maraciclatide scan before surgery, then compared the imaging results to what surgeons actually found during the operation. The alignment was striking: in 16 of 19 cases where both imaging and surgery were completed, the scan correctly predicted the presence or absence of disease. Among the 17 patients who had endometriosis confirmed surgically, the imaging detected it in 14 cases. Critically, there were no false positives—no patients were told they had disease when they did not. The scan also caught two cases of thoracic endometriosis, a rare variant that conventional imaging often misses entirely.
The real breakthrough lies in what the scan can detect that ultrasound and MRI cannot. Superficial peritoneal endometriosis, the earliest and most common form of the disease, accounts for 80 percent of all laparoscopically diagnosed cases. Yet it remains nearly invisible to standard imaging. Among the study participants, ten women with superficial peritoneal endometriosis had undergone transvaginal ultrasound or MRI within the previous year—and none of those conventional scans had found anything. The maraciclatide imaging found it. For the first time, researchers had a non-invasive way to visualize the disease at its most elusive stage.
Dr. Tatjana Gibbons, the study's lead author, called the results a potential turning point for women whose symptoms have long been dismissed or misdiagnosed. Professor Christian Becker, co-director of Oxford's Endometriosis CaRe Centre, emphasized that the diagnostic challenge of endometriosis is compounded by its vague presentation—pelvic pain, heavy periods, infertility—symptoms that could signal any number of conditions. Without reliable biomarkers or imaging tools, women have historically faced a choice between living with uncertainty or undergoing surgery. If Phase 3 trials confirm these findings, Becker said, maraciclatide could reduce diagnostic delays and provide a validated endpoint for developing new treatments, transforming both clinical practice and drug development.
The study was small and conducted at a single center, which is why the next step matters. Phase 3 multi-centre international trials are scheduled to begin later this year, with FDA Fast Track Designation already granted to accelerate the regulatory pathway. David Hail, CEO of Serac Healthcare, noted that the Phase 2 cohort included women already receiving hormone therapy, suggesting the scan's real-world performance will hold up in diverse patient populations. If the larger trials reproduce these results, the imaging agent could move toward regulatory approval and clinical availability within the next few years. For women who have spent years seeking answers, that timeline represents something close to hope.
Citações Notáveis
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.— Dr. Tatjana Gibbons, lead author, Nuffield Department of Women's and Reproductive Health
If these Phase II results are reproduced in the Phase III studies, maraciclatide has the potential to be an extremely valuable tool, as it could both reduce diagnostic delays and provide a validated endpoint for the development of new therapeutics.— Professor Christian Becker, Co-Director of the Endometriosis CaRe Centre
A Conversa do Hearth Outra perspectiva sobre a história
Why does endometriosis diagnosis require surgery right now? Can't doctors just look inside some other way?
The tissue grows on organs deep in the pelvis—behind the uterus, on the bowel, on the peritoneum. Ultrasound and MRI can see large cysts or scarring, but the earliest form, superficial peritoneal endometriosis, is thin and scattered. It's essentially invisible to those tools. Surgery is the only way to be certain.
So this radiotracer—it's not looking at the tissue itself. It's looking for something the tissue does.
Exactly. Endometriosis triggers new blood vessel growth because the lesions are inflamed and need oxygen. The tracer binds to a protein that marks that new vessel formation. It's like following the inflammation's signature rather than the lesion itself.
And in the study, it found disease that surgery confirmed, but conventional imaging had missed.
In ten cases, women had already had ultrasound or MRI that showed nothing. The radiotracer found the disease in most of them. That's the gap it fills—the cases that fall through the cracks.
What happens if Phase 3 doesn't work as well?
That's the real question. Phase 2 is small, one center, controlled conditions. Phase 3 will test it across multiple hospitals, different populations, real-world messiness. If the accuracy holds, it changes everything. If it doesn't, we're back to surgery.
How long until women could actually get this scan?
If Phase 3 succeeds, probably three to five years before regulatory approval and clinical availability. But the FDA Fast Track designation suggests they're moving quickly. The need is urgent enough that the process is accelerated.