The role of diffusion-weighted magnetic resonance imaging (DWI) to differentiate breast lesions in vivo was evaluated. Sixty women (mean age, 53 years) with 81 breast lesions were enrolled. A coronal echo planar imaging (EPI) sequence sensitised to diffusion (b value=1,000 s/mm(2)) was added to standard MR. The mean diffusivity (MD) was calculated. Differences in MD among cysts, benign lesions and malignant lesions were evaluated, and the sensitivity and specificity of DWI to diagnose malignant and benign lesions were calculated. The diagnosis was 18 cysts, 21 benign and 42 malignant nodules. MD values (mean +/- SD x 10(-3) mm(2)/s) were (1.48 +/- 0.37) for benign lesions, (0.95 +/- 0.18) for malignant lesions and (2.25 +/- 0.26) for cysts. Different MD values characterized different malignant breast lesion types. A MD threshold value of 1.1 x 10(-3) mm(2)/s discriminated malignant breast lesions from benign lesions with a specificity of 81% and sensitivity of 80%. Choosing a cut-off of 1.31 x 10(-3) mm(2)/s (MD of malignant lesions -2 SD), the specificity would be 67% with a sensitivity of 100%. Thus, MD values, related to tumor cellularity, provide reliable information to differentiate malignant breast lesions from benign ones. Quantitative DWI is not time-consuming and can be easily inserted into standard clinical breast MR imaging protocols.

: MRI largely outperformed mammography, ultrasonography, and their combination for screening high-risk women below and over 50.

Mammography and stereotactic biopsy still remain the only techniques for characterising microcalcifications. MRI cannot be considered a diagnostic tool for evaluating microcalcifications. It is, however, useful for identifying DCIS with more aggressive histological grades. An important application of MRI in patients with DCIS associated with suspicious microcalcifications could be to evaluate disease extension after a microhistological diagnosis of malignancy, as it allows a more accurate presurgical planning.

This preliminary study seems to indicate that low values of pre-chemotherapy MD may identify, before starting treatment, the patients with higher probability of response in terms of percentage of volume reduction of the lesion. MD may represent a complementary parameter useful to correctly select patients for neoadjuvant chemotherapy.

The clinical use of breast magnetic resonance (MR) imaging is increasing, especially for applications requiring paramagnetic contrast-agent injection. This document presents a synthetic list of acceptable indications with potential advantages for women according to evidence from the literature and the expert opinion of the panel that developed this statement. We generally recommend that breast MR imaging be performed in centres with experience in conventional breast imaging [mammography and ultrasonography (US)] and needle-biopsy procedures (under stereotactic or US guidance) as well as in breast MR imaging and second-look US for findings not revealed by conventional imaging performed before MR imaging. In our opinion, there is no evidence in favour of breast MR imaging as a diagnostic tool to characterise equivocal findings at conventional imaging when needle-biopsy procedures can be performed, nor for the study of asymptomatic, non-high-risk women with negative conventional imaging. After a description of technical and methodological requirements, we define the indications and limitations of breast MR imaging for surveillance of high-risk women, local staging before surgery, evaluation of the effect of neoadjuvant chemotherapy, breast previously treated for carcinoma, carcinoma of unknown primary syndrome, nipple discharge and breast implants.