DIFFUSION-WEIGHTED IMAGING IN BREAST LESION EVALUATION Belli P, Costantini M, Bufi E, Magistrelli A, La Torre G, Bonomo L.

Purpose. The purpose of this study was to investigate the ability of diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) in the detection and characterisation of breast lesions. Materials and methods. From September 2005 to September 2007, 86 patients with breast lesions who underwent magnetic resonance imaging (MRI) in our department were included in our study. MRI was performed with a 1.5-T unit using a standard protocol including DWI sequence. For each breast lesion, the ADC value was calculated and compared with that of normal breast tissue and to the definitive pathological diagnosis. Mann- Whitney U and Kruskal-Wallis tests were used for statistical analysis. Results. A total of 126 breast lesions were detected. Pathology results revealed 100 malignant and 26 benign lesions. Mean diameter of lesions was 26.02 mm (range 4–90 mm), including 52 lesions ≤15 mm in size. Mean ADC value of normal glandular tissue was 1.55×10–3 mm2/s. Mean ADC value of malignant lesions was 0.97×10–3 mm2/s. Mean ADC value for benign lesions was 1.66×10–3 mm2/s. Benign lesions showed ADC values significantly higher than malignant lesions (p<0.0001). Conclusions. DWI provides reliable information to support MRI diagnosis of breast masses. ADC value appears a promising adjunctive parameter in distinguishing malignant from benign breast lesions.