Figure 7b. Mirror image interpretation. (a) Bilateral mediolateral oblique mammograms reveal an irregular mass posteriorly on the left side with a highly suspect appearance (arrow). In addition, a subtle distortion is noted more inferiorly (arrowhead), a finding that becomes more evident with mirror image interpretation. (b, c) On left craniocaudal spot compression mammograms, the posterior (b) and anterior (c) lesions demonstrate a spiculated appearance (arrowhead in c). Pathologic analysis demonstrated multicentric invasive ductal carcinoma.