A region-based active contour method for extraction of breast skin-line in mammograms

In this work, we present a novel region-based active contour technique to extract the breast boundary in mammograms. Skin-line extraction in mammograms is non-trivial due to the presence of noise, intensity inhomogeneities, and scanning artifacts. Also, weak contrast near the skin-line boundary, especially in the case of low-density breasts, poses a lot of difficulty in its extraction. Here, we represent the breast boundary by a smooth, parametric curve. The region based data term of the active contour energy is based on the assumption that in a small neighborhood around the skin boundary, the intensity is piece-wise constant. Further, to achieve a good initial guess, we make use of the assumption that at a large scale, the breast image is binary with a fuzzy boundary. A PDE based energy is employed to get the fuzzy membership function. The smoothness term of the above energy allows us to handle noise/ scanning artifacts in mammograms, and allows easy extraction of a single contour, which is then input to the active contour energy. Our experiments on the MIAS database gave promising results as validated by an experienced radiologist.