Correspondence between different view breast X rays using curved epipolar lines

In this paper, we propose a method for matching a deformable object between time-varying stereo images. This method has been developed primarily to find correspondences between a cranio-caudal (CC) (head to toe) and a medio-lateral oblique (MLO) (shoulder to the opposite hip) X-ray mammogram of the same breast. The two mammograms are taken while the breast is compressed between the cassette and plate of the X-ray machine. This results in a different amount of compression in each direction. The deformations of the breast caused by the different compressions cause corresponding points to appear far from straight "epipolar lines" familiar from binocular stereo vision. The method developed in this paper calculates the curve in a MLO image corresponding to a point in the CC image through simulation of the differential deformation and the projection of a 3D curve corresponding to the point. Experiments on real data show that the method predicts well the corresponding position in the other image. We also illustrate the program's ability to estimate the 3D position of a lesion in the uncompressed breast. (C) 2001 Academic Press.