[Breast MRI: the usefulness of diffusion-weighted sequences for differentiating between benign and malignant lesions]

To evaluate the usefulness of diffusion-weighted MRI sequences and of the apparent diffusion coefficient (ADC) to differentiate between benign and malignant breast lesions.

We prospectively studied 88 patients (aged 31 to 79 years) with 94 lesions (80 malignant and 14 benign) who were referred for preoperative local staging. All patients underwent dynamic MRI examination after intravenous contrast administration and a diffusion-weighted sequence with ADC calculation. The results obtained at diffusion-weighted imaging were correlated with those obtained at histological examination.

The mean value of the ADC for malignant lesions (1.12+/-0.25x10(-3)mm(2)/s) was significantly lower (p<0.001) than for benign lesions (1.61+/-0.52x10(-3)mm(2)/s). No significant differences in ADC values were found between the different subtypes of invasive carcinomas or between intraductal carcinoma and invasive carcinoma (p>0.05). Using an ADC lower than 0.95x10(-3)mm(2)/s as a threshold for malignancy, the sensitivity is 52% and the specificity is 100%.

Diffusion-weighted sequences provide additional information in breast MRI that is useful for differentiating between benign and malignant lesions, thus improving the specificity of the technique.