EP13.35: Radiomic analysis of endometriomas: predicting volumetric and symptomatic response to hormonal therapy

Objectives: To evaluate whether second-line magnetic resonance imaging (MRI) improves diagnostic accuracy beyond expert transvaginal sonography (TVS) in the preoperative assessment of deep endometriosis (DE), and if prior surgery influences diagnostic performance.Methods: In this prospective observational cohort study, women with suspected DE scheduled for surgery after expert ultrasound were included.TVS was performed according to the International Deep Endometriosis Analysis (IDEA) protocol, with MRI as a second-line investigation.Surgical and histopathological findings served as the reference standard.Diagnostic performance (sensitivity, specificity, predictive values, likelihood ratios, and Cohen's κ) was assessed for TVS, MRI, and their combination, stratified by prior surgical status.Results: Among 221 women with suspected DE, 189 underwent surgery, of whom 107 had both TVS and MRI and were available for analysis, 55 had previous abdominal surgery.Combined imaging improved sensitivity for rectosigmoid (+10.3%) and uterosacral ligament involvement (+29.2%),but reduced specificity for endometriomas (-19.0%),obliteration of the pouch of Douglas (-13.3%), and uterosacral ligaments (-20.3%).Accuracy for the urinary bladder and ureters decreased with addition of MRI (88/107, 82.2% to 81/107, 75.7%).Sensitivity for rectosigmoid lesions was higher with the combined method in patients with prior surgery, while TVS alone showed higher specificity for urinary tract DE in those without prior surgery.Conclusions: In a tertiary-care setting, MRI adds value to expert TVS by improving sensitivity for rectosigmoid and uterosacral ligament lesions, but at the cost of reduced specificity, making its benefit location-dependent.Diagnostic performance is influenced by prior surgery, with the combined approach improving detection of rectosigmoid lesions in previously operated patients, while TVS alone more reliably excludes urinary tract DE in those without prior surgery.EP13.