Inclusion Criteria:  Signed informed consent; Age > 18 years; Proven diagnosis of early BC of any size; Patients candidate to primary systemic therapy (PST); Positive axillary nodes at diagnosis, confirmed by either citology or histology confirmation. Patients with clear overt clinical and radiological nodal involvement might be enrolled as well without FNA or microhystology  Exclusion Criteria:  inflammatory BC; pregnancy; contraindication to PET; distant metastases; no surgery after PST; contraindication to MRI; claustrophobia; allergy to the MR contrast agent; severe renal insufficiency.