Differentiating malignant from benign breast lesions with type 2 or 3 kinetic curves using an apparent diffusion coefficient cutoff value on MRI

Introduction: A low apparent diffusion coefficient (ADC) value is associated with breast lesions suspected of malignancy.This study aimed to determine the optimal ADC cutoff value to differentiate malignant from benign breast lesions with kinetic curve types 2 or 3 on breast magnetic resonance imaging (MRI).Material and methods: This cross-sectional study included women with breast lesions classified as Breast Imaging Reporting and Data System (BI-RADS) category 4 or 5. ADC was measured using diffusion-weighted imaging (DWI) MRI, and the kinetic curve was assessed with dynamic contrast-enhanced (DCE) MRI.A receiver operating characteristic (ROC) curve was used to determine the optimal ADC cutoff for differentiating malignant from benign breast lesions.Histopathological diagnosis of the breast lesion served as the gold standard.Results: A total of 65 women with breast lesions exhibiting kinetic curve types 2 or 3 were included.An optimal ADC cutoff of ≤1.099 × 10 -3 mm 2 /s differentiated malignant from benign lesions, yielding a sensitivity of 88.5% (95% CI, 76.6-95.6), a specificity of 84.6% (95% CI, 54.6-98.1), a PPV of 95.8% (95% CI, 85.7-99.5), a NPV of 64.7% (95% CI, 38.3-85.8),and an accuracy of 87.7% (95% CI, 77.2-94.5).The accuracy of kinetic curve types 2 and 3 alone ranged from 49.2% to 50.8%, indicating limited diagnostic performance for each kinetic curve type and significantly lower accuracy than that of the optimal ADC cutoff value (87.7%) for predicting malignant breast lesions.Conclusion: The optimal ADC value of ≤1.099 × 10 -3 mm 2 /s demonstrated high diagnostic performance in differentiating malignant from benign breast lesions in patients with kinetic curve types 2 or 3. Incorporating it into clinical practice provides a quantitative parameter that complements the qualitative interpretation of the kinetic curve.