O-RADS US versus IOTA simple rules in the diagnosis of benign and malignant adnexal masses: a prospective study

Although many studies have validated the diagnostic performance of Ovarian-Adnexal Reporting and Data Systems ultrasound (O-‎RADS US), most have been observed by experienced sonologists, and relatively few by junior sonologists. The purpose of this study was to compare the diagnostic performance of the O-RADS US and the International Ovarian Tumor Analysis (IOTA) Simple Rules (SRs) in senior and junior sonologists to determine a more suitable assessment model for general clinical use.

We prospectively recruited 228 patients diagnosed with adnexal masses (AMs). Two senior sonologists acquired images and evaluated them following the O-RADS US and IOTA guidelines, and two junior sonologists reviewed and analyzed images and evaluated them following the same guidelines. In this research, pathological findings were used as the reference standard. Comparisons of categorical variables were made using the chi-square test, and comparisons of continuous variables were made using the two independent-samples t-test. The diagnostic performance of the models was compared by analyzing the receiver operating characteristic (ROC) curve. The kappa value (κ) was used to compare the interobserver agreement between the senior and junior sonologists and the agreement between each ultrasound method and the reference standard.

Of 228 AMs, 176 were benign and 52 malignant. The junior adjusted O-RADS US (> O-RADS 4a represents malignancy) had the highest diagnostic validity, with a sensitivity, specificity, and accuracy of 94.23%, 87.5%, and 89.04%, respectively, and ROC curve of 0.959 (95% CI, 0.924-0.980). Both junior unadjusted (> O-RADS 3 represents malignancy) and adjusted O-RADS US had significantly higher diagnostic performance than the junior SRs (AUC 0.951 and 0.959 vs. 0.840, P = 0.0003, 0.0001, respectively). Interobserver agreement between senior and junior sonologists using O-RADS US was moderate (κ = 0.465), and interobserver agreement between senior and junior sonologists using SRs, unadjusted, and adjusted O-RADS US was good (κ = 0.618, 0.657, and 0.718, respectively). The junior unadjusted O-RADS US, adjusted O-RADS US, and SRs showed good agreement with the pathological results (κ = 0.648, 0.724, 0.716, respectively).

When assisting sonologists in AM diagnosis, the O-RADS US, especially the adjusted O-RADS US, had higher diagnostic performance than the SRs, and it would be more suitable for general clinical application.