The general objective of the study is to verify the diagnostic accuracy of contrast-enhanced mammography (CEM) compared to breast magnetic resonance imaging in patients undergoing preoperative staging for breast neoformations that have already been diagnosed and in patients undergoing neoadjuvant chemotherapy. In addition to performing a preoperative breast resonance imaging, which is always performed in these patients, one contrast-enhanced mammography per patient is planned. In patients undergoing neoadjuvant chemotherapy, which usually undergo MRI examination at the beginning, mid-cycle and at the end of chemotherapy treatment, a CEM will also be acquired same way at the beginning, mid-cycle and at the end of chemotherapy treatment. The study requires, for the execution of the contrast-enhanced mammography exam, the administration of an iodinated contrast medium that is completely analogous to that used in computed tomography.