Junctional zone thickness on magnetic resonance imaging - a non-invasive diagnostic method for adenomyosis and beyond

BACKGROUND AND OBJECTIVES: Adenomyosis is a prevalent gynecologic disorder involving ectopic endometrial tissue within the myometrium. Magnetic resonance imaging (MRI) enables non-invasive diagnosis, yet the role of junctional zone (JZ) thickness in predicting coexisting intrauterine pathologies remains uncertain. This study evaluated the diagnostic and predictive value of MRI-based JZ thickness in hysterectomy-confirmed adenomyosis. MATERIALS AND METHODS: This retrospective study included 420 patients who underwent hysterectomy with preoperative MRI between 2020 and 2025. JZ thickness was measured on sagittal T2-weighted images, and histopathological findings were recorded. Logistic regression analyses were performed to identify independent predictors of intrauterine pathologies. Diagnostic accuracy was assessed using receiver operating characteristic (ROC) curves. RESULTS: The mean JZ thickness was 17.5 ± 3.8 mm. Histopathological evaluation confirmed adenomyosis in 97.1% of cases, with coexisting lesions including myomas (44.5%), endometrial polyps (7.9%), simple hyperplasia (6.2%), atypical hyperplasia (1.9%), and endometrial cancer (2.4%). JZ thickness demonstrated strong positive correlations with polyps (R = 0.46; P < 0.001), simple hyperplasia (R = 0.55; P < 0.001), atypical hyperplasia (R = 0.49; P < 0.001), and myomas (R = 0.38; P < 0.001). Logistic regression identified JZ thickness as the most consistent independent predictor of intrauterine lesions, with an odds ratio of 1.70 for atypical hyperplasia (95% CI 1.11-2.60; P = 0.014). ROC analysis revealed excellent discriminative ability for simple hyperplasia (AUC = 0.842), atypical hyperplasia (AUC = 0.888), and polyps (AUC = 0.840), while predictive performance for myomas was moderate (AUC = 0.661). CONCLUSIONS: MRI-based measurement of JZ thickness is a reliable, non-invasive biomarker for adenomyosis, demonstrating an additional predictive value for coexisting premalignant intrauterine pathologies. Incorporating JZ thickness thresholds into routine imaging evaluation may enhance risk stratification, reduce unnecessary invasive procedures, and inform about personalized management strategies in women with adenomyosis.