This is a prospective, non-randomised, exploratory study on ≤20 healthy female volunteers (\>18 years), and ≤45 female patients (\>18 years) diagnosed with primary breast cancer. Healthy volunteers (n≤20) will be scheduled to undergo an 23Na-MR examination. Patients scheduled for primary surgery (n≤30) will undergo a single MR examination, involving 23Na-imaging prior to their planned surgery. Immunohistochemical analysis will be performed on surgical tissue specimens to determine tissue markers of interest for correlation with the imaging findings. Patients undergoing neo-adjuvant therapy (n≤15) will undertake up to two (2) combined PET/MR examinations with FDG (18F-2-fluoro-2-deoxy-D-glucose) and 23Na-MRI. Patient imaging will occur at two time points prior to their planned surgery: (i) baseline (prior to initiation of treatment) and (ii) mid-treatment (after 3-4 cycles of chemotherapy). Histopathological analysis will be performed on pre-treatment biopsies for histological markers of interest for correlation with the imaging findings.