[Indications of MRI in the initial local staging of early-stage breast cancer]. / Mise au point sur la place de l'IRM dans le bilan initial du cancer du sein localisé

MR Imaging is the most sensitive technique for detecting breast cancer. In patients with breast cancer, the additional value of MRI is validated in patients candidates for a breast-conserving surgery and when: cancer is occult, size evaluation is difficult at standard imaging, parietal involvement is suspected, and before neoadjuvant chemotherapy. In fatty breasts, MRI is not routinely recommended, because of same performances as in standard imaging. In dense breasts, MRI becomes significantly more sensitive than mammography for detecting multifocality and multicentricity with a positive predictive value of 60% for detected additional foci. Thus, a decision of mastectomy should not be made solely on the basis of MRI and may require additional tissue sampling of areas of concern identified by breast MRI. The additional value of breast MRI is particularly useful in patients with dense breasts and high risk factors for local recurrence: young age (< 40 years), familial high risk, or because of a high-grade invasive cancer greater than 2 cm in size. Performing breast MRI in such patients underlies requirements: an expert breast imaging team, optimal MRI protocols, and radiologists working in concert with the multidisciplinary treatment team.