Diagnostic accuracy of a modified non-contrast O-RADS MRI scoring system: a retrospective study

OBJECTIVE: To develop a modified non-contrast O-RADS MRI scoring system and validate its diagnostic performance. MATERIALS AND METHODS: The modified non-contrast O-RADS MRI scoring system was developed by incorporating the significant signs from the standard O-RADS MRI system. This study retrospectively enrolled the 176 adnexal masses in cohort A. MRI imaging features were compared between benign and malignant tumors within this cohort. The diagnostic performance of the two scoring models was assessed by estimating the area under the curve (AUC), net reclassification improvement (NRI), and integrated discrimination improvement (IDI). In addition, 352 adnexal lesions from cohorts B and C were included to further evaluate the diagnostic ability of the modified scoring system. RESULTS: In cohort A, the papillary projections exhibiting the sea anemone sign were highly indicative of borderline lesions (p = 0.001). Diffusion restriction in solid components significantly distinguished benign from malignant masses (p = 0.001). The apparent diffusion coefficient (ADC) value of cystic components yielded a cutoff of 1.74 (p < 0.05). The DeLong test revealed no statistically significant difference in AUCs between the two systems in cohort A (p > 0.05). The NRI and IDI for the modified non-contrast O-RADS MRI scoring system were -4.13% and -0.04, respectively (all p > 0.05). In cohorts B and C, the AUCs were 0.933 and 0.910. CONCLUSION: The diagnostic efficacy of the modified non-contrast O-RADS MRI scoring system was comparable to that of the standard O-RADS MRI risk stratification system, facilitating the distinction between benign and malignant adnexal neoplasms. KEY POINTS: Question How can a modified non-contrast O-RADS MRI scoring system be developed, and can this scoring system accurately classify adnexal masses? Findings The modified non-contrast O-RADS MRI system demonstrates excellent diagnostic performance and reliable risk stratification of adnexal masses by evaluating key imaging features. Critical relevance statement The modified non-contrast O-RADS MRI scoring system contributes to the risk stratification of adnexal masses, particularly for patients who cannot undergo contrast agent administration. This system provides a reliable tool to optimize treatment strategies and improve patient outcomes.