Mixture Modeling for Digital Mammogram Display and Analysis

We have devised a mammogram modeling system which greatly simplifies the development of, and can improve the accuracy and consistency of, computer-aided display and analysis algorithms for digital mammography. Our system segments the five major components of a mammogram: background, uncompressed-fat, fat, dense, and muscle. Differences in the amount and distribution of these components account for much of the variation between mammograms. Via segmentation, the corresponding variations are isolated; automated algorithms can consider the components independently or adapt their parameters based on component-specific statistics. In this paper, we present our system and demonstrate its versatility. Our system is able to segment a wide variety of digital mammograms because of its combined use of geometric (i.e., gradient magnitude ridge traversal) and statistical (i.e., Gaussian mixture modeling) techniques. Using images from Fischer, General Electric, and Trex digital mammography units, we define and evaluate automated, component-based algorithms for (1) "general" intensity windowing, i.e., displaying a digital mammogram such that it resembles a screen-film mammogram for breast cancer screening; (2) componentspecific intensity windowing for breast lesion characterization; and (3) breast density estimation for breast cancer risk assessment.