NCT06377553

PET/MRI for Evaluation of Endometriosis

PET/MRI Evaluation of Endometriosis Using Intercellular Matrix Radiopharmaceuticals

• Status: Enrolling By Invitation
• Phase: —
• Study type: Observational
• Enrollment: 60 (estimated)
• Sponsor: Massachusetts General Hospital · Academic / Other
• Sex: Female
• Age: 18 Years – 70 Years
• Healthy volunteers: —

Summary

This study aims to determine if PET/MRI can detect endometriosis and potentially improve upon currently available non-invasive diagnostic capabilities. Specifically, the authors will investigate the ability of PET/MRI to detect and quantify endometriosis, as well as differentiate among subcategories such as inflammatory peritoneal lesions, fibrotic deep infiltrating endometriosis lesions (DIE), and ovarian endometriomas. The authors will compare \[68Ga\]CBP8 or \[18F\]-FAPI-74 PET/MRI imaging versus the current gold standard diagnostic methods, including laparoscopic surgery, clinical follow-up, and follow-up imaging.

Detailed description

Several imaging techniques, including ultrasound, computed tomography and magnetic resonance imaging (MRI), have been used for the detection of DIE, for mapping and staging endometriosis. Currently, the modalities most commonly used are transvaginal ultrasound (TVS) and magnetic resonance imaging MRI. TVS is generally considered a first-line technique.TVS, in highly experienced hands, meets the criteria for mapping DIE to the uterosacral ligaments, rectovaginal septum, vaginal wall, pouch of Douglas and rectosigmoid; however it is limited by its operator dependance and by the small field of view (FOV). MRI is commonly used for mapping lesions within the Douglas pouch and rectovaginal septum and rectosigmoid. MRI has shown acceptable diagnostic values, with pooled sensitivity and specificity for pelvic endometriosis of 94% and 77%, respectively. For rectosigmoid endometriosis, MRI's pooled sensitivity and specificity were 92% and 96%, respectively. However, MRI has limitations, specially in the evaluation of chronic fibrotic endometriosis and for assessing the peritoneum and extension beyond the pelvis as well as DIEs. There is a growing body of literature examining the role of PET/MRI in pelvic and abdominal malignancies and its potential superiority to MRI alone. However, there are no studies that used PET/MRI to investigate endometriosis. This study aims to use \[68Ga\]CBP8- or \[18F\]FAPI PET/MRI to diagnose and quantify endometriosis. The novel radiopharmaceutical collagen-binding probe 8 labeled with Gallium-68 selectively binds to collagen type I, the predominant extracellular protein in fibrosis. \[68Ga\]CBP8 has already been investigated in patients affected by pulmonary fibrosis with success. Fibroblast activation protein (FAP) is a type II transmembrane serine protease that is overexpressed in CAFs and, to a lesser extent, in benign processes. It is associated with extracellular matrix remodeling, for example, chronic inflammation, degenerative bone and spine disease, arthritis, and cardiac remodelling after myocardial infarction. Quinolone-based FAP inhibitors (FAPIs) constitute a class of molecules with high affinity to FAP deployed to assess many types of solid tumors and some benign pathologies. 68Ga-FAPIs and, to a lesser extent, 18F-FAPI are being extensively studied in oncologic and non-oncologic positron emission tomography/computed tomography (PET/CT) and, to a lesser extent, PET/MRI, both in Europe and Asia. In this single-arm, single-center, open label prospective study, the authors will recruit 60 patients with clinical diagnosis of endometriosis who candidate for laparoscopic surgery. Patients will be referred to FAPI- or CBP8-PET/MRI by their primary treating gynecologist physicians. Laparoscopy will serve as primary standard of reference; clinical and imaging follow up, as well as prior diagnostic imaging studies (CT, MRI, US), will serve as secondary standard of reference. In the case patients will not undergo laparoscopy, then clinical and imaging follow up, as well as prior diagnostic imaging studies (CT, MRI, US), will serve as primary standard of reference. Board-certified radiologists will evaluate \[18F\]-FAPI-74 or \[68Ga\]CBP8-PET/MR images and standalone MR images in a blinded fashion on separate occasions. Assessment of of endometriosis will be performed according to consolidated published criteria for MRI. For endometriosis staging, the readers will follow rASRM criteria. Then, the authors will compare the sensitivity, specificity, and accuracy of regional/whole-body staging using FAPIor CBP-PET/MRI versus regional/wholebody MRI, with the standard reference set as pathology results, when available, or clinical and imaging follow-up otherwise. Hypothesis testing will be performed using McNemar's test for matched pairs testing.

Conditions

• Endometriosis
• Endometrioma

Interventions

Type	Name	Description
DRUG	Radiotracer Injection	An intravenous catheter will be placed in an arm or hand vein for injection of \[68Ga\]CBP8; 6-10 mCi of \[68Ga\]CBP8 or 5-9 mCi of FAPI will be injected into the Biograph mMR system. The injected dose and the time of injection will be recorded; The catheter will be flushed with 0.9% saline solution; The subjects will then be positioned on the scanner table; support devices under the back or legs will be used to enable the patient to maintain his/her position throughout the scan comfortably.
DIAGNOSTIC_TEST	Imaging	MRI and PET scanner to be used: 3.0 T Laboratory (Bay 7) Siemens Biograph mMR. Magnetic resonance images of the pelvis and abdomen will be acquired using the Martinos Center's combined 3 Tesla PET/MRI scanner. The image quality on these 3 Tesla devices will be very high, equivalent to or better than any other standard clinical MRI system. PET images of the target body site will be acquired when necessary, the data acquisition will be started shortly before radiotracer injection; Coincidence event data will be acquired and stored in list mode or compressed (i.e., sinogram space) format. Subjects will be asked to lie still for the duration of the study. The entire imaging session will last up to 120 minutes
OTHER	Rectal Ultrasound Gel Injection	About 50ml of ultrasound gel will be placed into the vagina using the blunt end of the ultrasound gel tube or a Foley catheter or a syringe with a blunt Christmas tree end. No ultrasound probe will be inserted into the vagina, no external ultrasound probe will be used. No ultrasound study will be performed. The ultrasound gel will only be used to distend the vagina and improve the quality of MRI images; this is standard of practice in MRI for endometriosis and for several other gynecological diseases.

Timeline

• Start date: 2025-01-06
• Primary completion: 2028-01-03
• Completion: 2029-05-03
• First posted: 2024-04-22
• Last updated: 2026-03-12

Locations

1 site across 1 country: United States

Regulatory

• FDA-regulated drug study