Study To Investigate the Feasibility and Safety of A Dedicated High Resolution Nuclear Breast Imaging Camera

Inclusion Criteria: * Females ≥18 years of age * Undergoing annual breast MRI because of a high risk of breast cancer due to any of the following: * Known BRCA1 or BRCA2 mutation carriers, or is untested for BRCA but is a first degree relative of a BRCA mutation carrier * History of radiation to the chest between 10-30 years of age (e.g. Hodgkin's Disease) * History of Cowdens or Li Fraumeni Syndrome * A first degree relative with Cowdens or Li Fraumeni Syndrome * Prior breast biopsy positive for lobular carcinoma in situ (LCIS) or atypical lobular hyperplasia or atypical ductal hyperplasia (ADH) * Family history consistent with a hereditary breast cancer syndrome and estimated personal lifetime cancer risk ≥25% using the IBIS risk evaluator Exclusion Criteria: * Pregnant or lactating * History of invasive breast cancer or ductal carcinoma in situ (DCIS) * Unable to undergo MRI because of: * Renal dysfunction with an estimated creatinine clearance of \< 30 ml/min calculated using the Cockcroft-Gault formula * Implanted ferrous metal prostheses * Claustrophobia * Medical or psychological conditions that on assessment, make them unable to complete the procedure * Known allergies to Gadolinium-DTPA * Known allergies to Sestamibi (Miraluma or Cardiolite) * Prior bilateral mastectomy * Prior breast biopsy or surgery within 3 months