OBJECTIVE: To study the utility of diffusion-weighted magnetic resonance imaging in the differentiation between benign and malignant breast lesions. MATERIALS AND METHODS: Forty-five women (mean age, 46.1 years) with 52 focal breast lesions underwent diffusionweighted magnetic resonance imaging. The calculation of apparent diffusion coefficient (ADC) was based on the ADC map reflecting five b values (0, 250, 500, 750, and 1000 s/mm²). The mean ADC value of each lesion was correlated with imaging findings and histopathologic results. Cutoff ADC, sensitivity and specificity of diffusion-weighted imaging in the differentiation between benign and malignant lesions were calculated. P < 0.05 was considered as statistically significant. RESULTS: The mean ADC was significantly lower for malignant lesions (0.92 ± 0.26 × 10-3 mm²/s) as compared with benign lesions (1.50 ± 0.34 × 10-3 mm²/s) (P < 0.0001). Diffusion-weighted imaging showed high sensitivity and specificity (both, 92.3%) in the differentiation between benign and malignant lesions. CONCLUSION: Diffusion-weighted imaging is a potential resource as an adjuvant to breast magnetic resonance imaging to differentiate benign from malignant lesions. Such sequence can be easily added to the standard breast magnetic resonance imaging protocol, without implying any significant increase in examination time.

Keywords: Breast cancer, Diffusion-weighted imaging, Magnetic resonance imaging

OBJECTIVE: To review the literature about the positive predictive value of Breast Imaging Reporting and Data System (BI-RADS®) categories 3, 4 and 5. MATERIALS AND METHODS: A research was performed in the online Medline database, entering the terms "predictive value" and "BI-RADS". Eleven studies were included in this review. RESULTS: The positive predictive values ranged respectively between 0% and 8%, 4% and 62%, and 54% and 100% for BI-RADS® categories 3, 4 and 5. Three studies have also evaluated morphological criteria with higher positive predictive value in mammography, mass with spiculated margins being the finding with highest positive predictive value for malignancy. CONCLUSION: A high variability was found in the reviewed literature among positive predictive values of BI-RADS® categories 3, 4 and 5, although methodological differences have been identified, limiting the comparative analysis.

Keywords: Mammography, BI-RADS®, Breast cancer