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Figure 4a. Bilateral screening mammograms in a 68-year-old woman with heterogeneously dense breast tissue were initially interpreted as negative. Two cancers, one in the upper inner and the other in the upper outer portion of the left breast, were detected on screening mammograms obtained 10 months later. (a, b) There is a spiculated dense mass (straight arrow) in the upper inner portion of the left breast. Reasons for possible miss include the location of the lesion at the chest wall, at the edge of the film, and at the edge of glandular tissue. This lesion is more obvious than the subtler spiculated mass in the upper outer quadrant (curved arrow). (c) CAD images show the more subtle spiculated lesion marked by an asterisk on the left CC view only. The denser spiculated lesion near the chest wall (not marked) presents an example of the lower sensitivity of CAD in the posterior portion of the breast. The asterisk in the right MLO view is a false-positive CAD mark in an area of benign-appearing breast density.