Added Value of Quantitative Analysis of Diffusion‐Weighted Imaging in <scp>Ovarian‐Adnexal</scp> Reporting and Data System Magnetic Resonance Imaging

Abstract

Background The ovarian‐adnexal reporting and data system‐magnetic resonance imaging (O‐RADS‐MRI) score decreases the incidence of indeterminate adnexal masses from 18% to 31% with ultrasound till 10.8% to 12.5% with MRI. Further improvement of this score may be useful to improve patients' management. Purpose To evaluate the added value of quantitative diffusion‐weighted imaging (DWI) in the diagnosis of adnexal masses classified according to the O‐RADS‐MRI score. Study type Prospective cohort study with retrospective DWI analysis. Population Among 402 recruited patients, surgery was done only in 163 women (median‐age: 51 years) with 201 indeterminate adnexal masses, which were included in the final analysis. Field strength/sequence Standardized MRI (1.5 and 3‐T) including diffusion and dynamic contrast‐enhanced sequences (diffusion‐weighted single‐shot spin‐echo echo‐planar imaging) were used. Assessment Two radiologists classified the adnexal masses according to O‐RADS‐MRI and they were blinded to the pathology report. Two methods of quantitative analysis were applied using region‐of‐interest apparent‐diffusion‐coefficient (ROI‐ADC) and whole‐lesion ADC‐histogram (WL‐ADC). Statistical tests Fisher's exact and Mann–Whitney‐U tests were used to compare variables among malignant and benign lesions. Receiver‐operating‐characteristic (ROC) curves were constructed to examine the sensitivity/specificity of each parameter. ROI‐ADC and WL‐ADC of lesions with O‐RADS‐MRI score‐4 were plotted to identify thresholds of malignant lesions. The improvement of the O‐RADS‐MRI score after adding these thresholds was assessed by two ROC‐curves. A P &lt; 0.05 was considered to be statistically significant. Results Fifty‐eight of the 201 lesions (28.9%) were malignant. The ROI‐ADC and the WL‐ADC means of malignant lesions were significantly lower than those of benign lesions. Forty‐two lesions (20.9%) had an O‐RADS‐MRI score‐4. In this subgroup, 76% of lesions with ROI‐ADC &lt; 1.7 × 10 −3 mm 2 /sec and WL‐ADC &lt; 2.6 × 10 −3 mm 2 /sec were malignant, whereas only 11.8% with ROI‐ADC ≥ 1.7 × 10 −3 mm 2 /sec or a WL‐ADC ≥ 2.6 × 10 −3 mm 2 /sec were malignant. The overall performance of the O‐RADS‐MRI score combined with these thresholds was improved. Data conclusion Integrating ADC‐thresholds in O‐RADS‐MRI score‐4 may discriminate low‐to‐intermediate and intermediate‐to‐high malignancy risk groups. Level of Evidence 2 Technical Efficacy Stage 2

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