MRI evaluation and characterization of adnexal lesions using a modified, non-DCE O-RADS MRI Scoring System: A prospective diagnostic accuracy study

Abstract

ABSTRACT

Background: Ovarian cancer is a major global health issue and a leading cause of cancer-related deaths among women. While ultrasound is the primary imaging tool, up to 25% of cases remain indeterminate. Magnetic Resonance Imaging (MRI) serves as a crucial second-line tool, and the Ovarian-Adnexal Reporting and Data System (O-RADS) MRI scoring system provides a structured framework for risk stratification.

Objectives: To evaluate and characterize adnexal lesions using the O-RADS MRI scoring system and correlate findings with histopathological results.

Methods: A single-center prospective diagnostic accuracy study enrolled 100 patients with adnexal lesions between December 2023 and December 2024 at Nepalgunj Medical College, Nepal. All patients underwent MRI on a 1.5 Tesla scanner. Lesions were classified using the O-RADS MRI scoring system and results were correlated with histopathological diagnosis.

Results: Of 100 adnexal lesions evaluated, 77 were benign and 23 were malignant. Using O-RADS ≥4 as the threshold for malignancy, the O-RADS MRI system demonstrated an overall accuracy of 93% (95% CI: 88–98%), sensitivity of 87% (95% CI: 73.1–100%), and specificity of 94.8% (95% CI: 89.9–99.7%). All O-RADS 2 lesions were benign, and all O-RADS 5 lesions were malignant. The negative predictive value was 96.1%.

Conclusion: Using a modified, non-DCE-based O-RADS MRI protocol, this scoring system was a reliable and accurate method for distinguishing benign from malignant adnexal lesions, with strong histopathological correlation. Its structured framework supports improved diagnosis, reduced unnecessary surgeries, and optimized patient management, even in settings where DCE-MRI is unavailable.

Keywords: Adnexal lesions; Diagnostic accuracy; Histopathology; O-RADS MRI; Ovarian cancer; Risk stratification