Diffusion and apparent diffusion coefficient in BI-RADS 6 lesions: Correlation with histopathological findings

Abstract

Objective: To assess the diagnostic value of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) in BI-RADS (Breast Imaging Reporting and Data System) category 6 breast lesions and their correlation with histopathological findings in patients at Policlínica Metropolitana, January 2024–August 2025. Materials and methods: Observational, descriptive, retrospective study including 78 patients with BI-RADS 6 lesions evaluated by MRI with DWI sequences and ADC maps, confirmed histologically. Demographic data, tumor distribution, diffusion restriction, ADCmean values, and histological type were recorded. Results: Most patients were aged 60–74 years (35.9 %), with lesions predominantly in the left breast (57.7 %). All lesions exhibited diffusion restriction. ADC values mainly ranged 0.92–1.29 ×10⁻³ mm²/s. Invasive ductal carcinoma was the most common subtype (64.1 %), followed by invasive lobular carcinoma (21.8 %). No significant associations were observed between ADC values, histology, tumor distribution, or recurrence. Conclusions: DWI and ADC demonstrated high diagnostic value in BI-RADS 6 lesions, showing universal diffusion restriction and values typical of malignancy. Although they do not differentiate histological subtypes or predict recurrence, they remain essential functional imaging tools. Future studies should include BI-RADS 4 and 5 lesions to further evaluate diagnostic performance