Diagnostic reliability of O-RADS score based on non-dynamic contrast-enhanced MRI and apparent diffusion coefficient...

To evaluate the diagnostic performance and inter-rater reliability of (O-RADS) MRI based on non-dynamic contrast-enhanced (DCE) MRI and the value of apparent diffusion coefficient (ADC) in the characterization of adnexal masses.

Retrospective analysis was done for 148 patients with 191 adnexal masses who underwent non-DCE MRI and diffusion-weighted imaging (DWI). Two independent radiologists classified the masses into five categories according to O-RADS-MRI and measured ADCmean values for solid and cystic components. The final diagnoses were determined by postoperative histopathology. Logistic regression analysis was performed to detect predictors of malignancy.

There was excellent inter-rater agreement in assessing O-RADS categories (k_w=0.901 and 95% CI = 0.863 to 0.939). Solid tissue enhancement more than the myometrium at 30-40 s at non-DCE MRI was statistically significantly higher in malignant lesions (p < 0.001). There was also excellent reliability (absolute inter-rater agreement) in measuring ADCmean values. The ADCmean of solid and cystic components at cutoff values of ≤ 1.3 × 10 - 3 mm2/s and > 2.07 × 10 -3 mm²/s are perfect and excellent discriminators for differentiating malignant and benign adnexal masses (AUC = 1.000 and 0.952) respectively. Multivariate regression analysis revealed that the presence of simple fluid, low DW signal of cystic component, and ADCmean of cystic component > 2.07 × 10 -3 mm²/s were statistically significant independent predictors of malignancy in an O-RADS-MRI score > 3 adnexal lesions.

O-RADS-MRI score utilizing non-DCE MRI is a reliable system with high PPV. ADCmean value is a non-invasive excellent discriminator for differentiating adnexal lesions that could improve O-RADS-MRI score performance and treatment plan.