Breast cancer is the most common cancer in women worldwide, with nearly 1.7 million new cases diagnosed in 2012. This represents about 12% of all new cancer cases and 25% of all cancers in women. The current standard method for detecting non-palpable early stage breast cancer is X-ray mammography. Despite the fact that X-rays provide high-resolution images at low radiation doses, its limitations are well documented. In the U.S., up to 75% of all malignancies identified by X-ray mammography are later found to be benign after biopsies. These false positive conclusions result in unneces- sary biopsies, causing considerable distress to the patient and an unneces- sary financial burden on the health service. Much more worryingly, up to 15% of all breast cancers present at the time of screening are missed by conventional mammography, often delaying treatment to the point where it’s no longer effective. One of the most promising alternative imaging modalities is Microwave Imaging. Microwave Imaging is based on the dielectric contrast between healthy and cancerous breast tissue at micro- wave frequencies. Microwave imaging is non-ionising, non-invasive, does not require uncomfortable breast compression, and is potentially low cost.