1. A method comprising: obtaining a plurality of x-ray tomosynthesis projection images of a patient's breast; reconstructing the plurality of x-ray tomosynthesis projection images into a three dimensional reconstructed image comprising a plurality of slices; and synthesizing a two-dimensional mammogram using at least a subset of the three-dimensional reconstructed image, wherein the step of synthesizing includes projecting at least one tomosynthesis slice image having a pixel spacing that differs from a pixel spacing of a mammogram onto a mammogram coordinate system; and displaying the synthesized mammogram on a display device.