The sensitivity of conventional mammography for evaluation of extent of disease, detection of multifocal breast cancers and contralateral breast cancers is poor. Molecular Breast Imaging (MBI) is a new nuclear medicine technique that permits the breast to be imaged in a manner similar to mammography, utilizing a Cadmium-Zinc-Telluride (CZT) gamma camera. We have developed the first dual-head MBI system in the world and preliminary results from this system indicate a high sensitivity (~90%) for the detection of breast cancers < 10mm.