Quantitative diffusion weighted imaging (DWI) improves the diagnostic accuracy of the O-RADS MRI scoring system in indeterminate adnexal lesions.

Background: Despite the overall high accuracy of the O-RADS MRI scoring system for characterization of indeterminate adnexal lesions, a non-negligible percentage of adnexal lesions remains indeterminate. Given this, the main objective of this study was to evaluate the value of adding quantitative diffusion-weighted imaging (DWI) to Ovarian-Adnexal Reporting and Data System (O-RADS) MRI to improve the diagnostic accuracy of the scoring system in a cohort of indeterminate adnexal lesions according to International Ovarian Tumor Analysis Group Simple Rules (IOTA-SR).

Methods: Seventy-nine women with 81 pelvic lesions classified as indeterminate according to IOTA-SR underwent 3-Tesla MRI with a conventional multiparametric protocol. DWI was quantitatively analyzed. Lesions were surgically removed or followed-up, according to a local protocol. Sensitivity, specificity, positive and negative predictive values and accuracy were determined for conventional multiparametric MRI and quantitative DWI-derived data.

Results: Twenty masses in 72 patients (27.8%) were malignant. An apparent diffusion coefficient (ADC) cut-off value of 1.30 × 10-3 mm2/s had 89% sensitivity and 80% specificity for malignancy. Overall, adding quantitative DWI to O-RADS MRI increased the specificity (98.08%, P < .001), positive predictive value (94.12%, P < .001), and accuracy (93.06%, P = .05). In the specific O-RADS MRI score 4 subgroup, an ADC cut-off value of 1.22 × 10-3 mm2/s had 86% sensitivity and 67% specificity for distinguishing benign from malignant lesions.

Conclusions: In IOTA-SR indeterminate adnexal lesions, quantitative DWI significantly improves the diagnostic performance of conventional multiparametric MRI in all O-RADS MRI score groups.