This research investigated the state of art of computer aided detection systems for digital mammograms, and evaluated the related techniques in image pre-processing, feature extraction and classification of digital mammograms. Furthermore, this paper explored the further research directions for next generation CAD for mammograms. It was identified that computer-aided detection techniques for masses and microcalcifications have been extensively studied, but the detection techniques for architectural distortion and asymmetry in mammograms still are challenges
