Results of this study show that readers are able to improve detection performance when they use CAD for interpretation of mass lesions in an interactive way. The beneficial effect of CAD can be attributed fully to improvement of interpretation, because traditional CAD prompts to avoid perceptual oversights were not shown. The effectiveness was remarkable given that the readers in this study used the interactive system for the first time and had limited training. It is noted that in a previous experiment using a similar observer study design and dataset no significant improvement with traditional CAD prompting was found when readers had limited training [23]. This suggest that for mass detection interactive CAD may be more effective than traditional CAD. This is in accordance with studies suggesting that interpretation errors are more common than perception errors [10, 11].