Breast cancer has become a major health problem affecting each twelfth of all women during their lifetime; it is now the most frequently occurring malignant disease in women. Breast cancer can occur in men, although the incidence is much lower, amounting to around 1% of all breast cancers.Although the X-ray mammography is the primary diagnostic tool in breast cancer today, it does have limitations, and so does ultrasound which is a valuable tool to use with mammography. Accordingly, the metabolic information provided by FDG-PET has emerged as a useful tool in non-invasive characterization of indeterminate lesions.