Figure 4a. Obscured mass due to infiltrating ductal carcinoma and branching and/or fine linear calcifications due to infiltrating ductal carcinoma and ductal carcinoma in situ in a 71-year-old woman. (a) Craniocaudal routine mammogram shows partially obscured mass (arrow) and several groupings of calcifications (arrowheads). (b) Mediolateral oblique spot-compression mammographic view of the mass (arrow) again shows partially obscured or indistinct margins. Since the participants were told to assume that all masses were solid, biopsy was the appropriate recommendation, made prospectively by two of the three experienced imagers. Initially, 68% of participants considered this benign or probably benign. With training, 64% recommended biopsy. (c) Craniocaudal spot-magnification mammogram of the outer right breast better demonstrates the cluster of branching and/or fine linear calcifications (arrow) suggestive of malignancy. The mass and calcifications were considered separate lesions, although participants were aware that the lesions were in the same breast. All participants initially recognized the morphology as either pleomorphic or branching and/or fine linear. In spite of this, 17% of participants initially classified the calcifications as benign or probably benign. After training, all participants recommended biopsy. The more posterior group of hazy calcifications (unlabeled) to the left of those marked with an arrow was due to ductal carcinoma in situ and was not part of the quiz.