A Computer-Aided Diagnosis (CAD) system is a set of automatic or semi-automatic tools developed to assist radiologists in the detection and/or classification of abnormalities presented in diagnostic images of different modalities. Although on the early phase of research and development CAD systems were criticized by some computer scientists; regardless of this criticism, nowadays’ experimental evidence indicates that success rates of radiologists increase significantly when they are helped by these systems: In mammography, researchers have reported results from prospective studies on a large number of screenees, regarding the effect of CAD on the detection rate of breast cancer. Although there is a large variation in the results, it is important to note that all of these studies indicated an increase in the detection rates of breast cancer with the use of CAD; as a consequence of this, using CAD contributes to decrease cancer-related deceases due to the early detection of cancer signs.