Combining a breast apparent diffusion coefficient category system with Breast Imaging Reporting and Data System...

To investigate the diagnostic performance of the predefined breast apparent diffusion coefficient (ADC-B) category system in differentiating malignant from benign breast lesions and to compare with the Breast Imaging Reporting and Data System (BI-RADS).

This was a single-institution retrospective study of patients who underwent breast MRI between April 2019 and May 2023. Dynamic contrast-enhanced (DCE) MRI and diffusion weighted imaging (DWI) were performed using a 3-T MRI system. Data on lesion morphology (mass, non-mass), size, and ADC were collected. Histology was the standard of reference. The analysis assessed the inter-reader agreement in measuring ADC and ADC-B category using the intraclass correlation coefficient (ICC), as well as the diagnostic performance based on the receiver operating characteristic (ROC) curve.

A total of 376 lesions in 358 women (mean age, 46.29 years; SD, 11.03) with pathologic results (236 malignant and 140 benign) were included. The inter-reader agreement was excellent in measuring ADC (ICC = 0.991) and assessing ADC-B category (ICC = 0.967). Overall diagnostic performance for ADC-B category (area under the curve [AUC], 0.858; 95% CI: 0.816-0.894) was higher than for BI-RADS (AUC, 0.805; 95% CI: 0.759-0.846; P = 0.029). The AUC of ADC-B category combined with BI-RADS reached 0.870 (95% CI: 0.829-0.904) for ADC-measurable lesions and 0.861 (95% CI: 0.822-0.894) for all lesions. The diagnostic combination significantly improves the specificity of BI-RADS (from 17.1% to 49.5% for ADC measurable lesions and from 20% to 45.6% for all lesions; P < 0.001) while maintaining sensitivity.

The combination of predefined ADC-B category and BI-RADS has the potential to enable classification of breast lesion types with high accuracy.

While DWI has been incorporated into clinical MRI protocols at numerous medical centres, it has not been included in the official BI-RADS criteria. Adding ADC-B category system to BI-RADS classification significantly improves the specificity of breast lesion classification without decreasing sensitivity compared to the BI-RADS alone.