Apparent diffusion coefficient on 3.0 Tesla magnetic resonance imaging and prognostic factors in breast cancer.

Aim: The aim of the study was to evaluate whether the apparent diffusion coefficient (ADC) provided by 3.0 Tesla diffusion-weighted imaging (3T DWI) varies with the prognostic factors Ki67 and grading in invasive breast cancer.
Materials and Methods: Seventy-three patients with 75 invasive breast cancer lesions who had undergone 3.0 Tesla magnetic resonance imaging (MRI) for local staging were enrolled. All lesions were confirmed by histologic and immunohistochemical analysis. MRI included both dynamic contrast-enhanced and DWI sequences. ADC value was obtained for each lesion. Histologic tumor grade was established according to the Nottingham Grading System (NGS), while Ki67 expression was evaluated by MM1 clone IgG1 mouse anti-human monoclonal antibody. Patients were divided into the following groups: grade 1 (G1), grade 2 (G2), grade 1 plus grade 2 (G1+G2) and grade 3 (G3), and low Ki67 (< or = 14%), intermediate Ki67 (15%-30%), and high Ki67 (> or = 30%). ADC values were compared with the G and Ki67 groups. Statistical comparison was carried out using the Mann-Whitney U and the Kruskal-Wallis H test.
Results: ADC values were significantly higher in G3 than in G1+G2 tumors; no significant difference was observed when G1, G2, and G3 were compared. There was no statistically significant correlation between ADC values and Ki67 percentage (p > 0.05).
Discussion: ADC values obtained on 3T DWI correlate with low (G1+G2) and high-grade (G3) invasive breast carcinomas.
Conclusion: ADC may be a helpful tool for identifying high-grade invasive breast carcinoma.