Radiotracer shows promise for endometriosis imaging

An investigational radiotracer may help visualize endometriosis on SPECT/CT, according to phase 2 results from the DETECT study published in The Lancet Obstetrics, Gynaecology & Women’s Health.

The study evaluated 99mTc-maraciclatide, a gamma-emitting radiotracer that binds to αvβ3 integrins. These integrins are upregulated during angiogenesis, the formation of new blood vessels, which is associated with inflammatory diseases such as endometriosis.

Researchers recruited 20 participants with suspected or confirmed endometriosis between March 2023 and September 2024. Of these, 19 underwent surgery after preoperative SPECT/CT imaging, including 17 who had laparoscopy and 2 who had thoracoscopy, according to the University of Oxford publication record.

Imaging results were concordant with surgical presence or absence of endometriosis in 16 of 19 cases. Endometriosis was imaged in 14 of 17 surgically positive participants, including 2 cases of thoracic endometriosis, and no false positives were reported, according to Serac Healthcare’s study announcement.

The findings are notable because superficial peritoneal endometriosis, the most common subtype, is difficult to detect reliably with conventional imaging such as ultrasound and MRI. Oxford researchers said this subtype represents about 80% of laparoscopically diagnosed disease and often requires surgery for definitive diagnosis.

99mTc-maraciclatide imaging visualized lesions across endometriosis subtypes and detected disease missed by conventional imaging methods, according to the study announcement. The radiotracer was also reported as well tolerated, with high patient acceptability.

“These exciting findings indicate that maraciclatide offers a highly promising diagnostic and monitoring tool, particularly for superficial peritoneal endometriosis,” said Tatjana Gibbons, MBBS, lead author and DETECT investigator at the University of Oxford.

The study remains early stage. It was single-center, exploratory, open-label, nonrandomized, and included a small patient group. Larger studies will be needed to confirm diagnostic performance before the tracer can be considered for routine clinical use.

Serac Healthcare said 99mTc-maraciclatide has received FDA Fast Track designation and that phase 3 study designs have been agreed. The company said it is moving toward larger trials and future regulatory submission.

Christian Becker, co-director of the Endometriosis Care Centre in Oxford and joint senior author, said the tracer could become “an extremely valuable tool” if phase 2 findings are reproduced in phase 3 studies.

For imaging specialists, the study points to a possible molecular imaging role in a condition where conventional imaging can miss early or superficial disease. If validated, SPECT/CT with 99mTc-maraciclatide could support diagnosis, monitoring, and treatment-response assessment in endometriosis.