Apparent Diffusion Coefficient in Estrogen Receptor–Positive Invasive Ductal Breast Carcinoma: Correlations with Tumor-Stroma Ratio

PURPOSE: To determine whether apparent diffusion coefficient (ADC) values vary according to tumor-stroma ratio, dominant stroma type, or presence of central fibrosis in estrogen receptor-positive breast cancer. MATERIALS AND METHODS: Institutional review board approval was obtained, and patient consent was waived. Sixty-one patients with estrogen receptor-positive invasive ductal carcinoma-not otherwise specified who underwent breast magnetic resonance (MR) imaging with diffusion-weighted (DW) imaging were included in this study. The ADC values of the lesions were measured. Two pathologists evaluated the tumor-stroma ratio, dominant stroma type (collagen, fibroblast, lymphocyte), and central fibrosis. Detectability on DW images was compared between the two groups according to the tumor-stroma ratio (stroma rich or stroma poor). Mean ADC values were retrospectively compared with the tumor-stroma ratio, dominant stroma type, and presence of a central fibrosis. Multiple linear regression analysis was performed to determine variables independently associated with ADC. RESULTS: On DW images, detectability was not significantly different between stroma-rich and stroma-poor groups (P = .244). ADC values were significantly lower in the stroma-poor group (P < .001). The mean ADC values in the collagen-dominant type were lower than in fibroblast-dominant or lymphocyte-dominant types (P = .021). In multiple linear regression analysis, tumor-stroma ratio (P = .007), tumor size (P = .007), and dominant stroma type (collagen dominant, P = .029) were independently correlated with ADC. CONCLUSION: In estrogen receptor-positive breast cancers, ADC values showed significant differences according to the tumor-stroma ratio and dominant stroma type.