Abstract

Background: The BIRADS score for mammographic density does not currently indicate which breast has the higher density, and may be at higher risk of developing (or having) cancer. A focal density (‘developing’) is a region that is apparent on a recent mammogram, is present in both CC and MLO views, but can only be seen in one breast. Using focal density (FD) quantification, we assign a density score to each breast separately in order to assess breast asymmetry.

Method: Our method, which substantially improves our previous method (RICE) [1], suppresses normal breast parenchyma in order to highlight ROIs (see Figure 1). It embodies the reasonable assumption that the neighborhood typically has a similar tissue density to that of the tissue encompassing the candidate masked tumor. In this preliminary study, the method was applied to 11 patient cases of very dense mammograms, each of which contained at least one cancer. Our method produces a density score for each individual breast and determines asymmetry as a percentage score.

Results: Table 1 summaries our results. Except for a single instance (CL0081 – a marginal case), all asymmetric FD scores indicate the laterality of the cancer. All mammograms were pre-processed with Volpara breast density quantification software [2]. We note that in some cases (i.e. CL0037, CL0077, CL0090) where the volumetric density grade percentage VGD% is very similar for both the left and right breast, our method effectively produces distinct FD scores confirming to the laterality of cancer.

Conclusion: We assessed asymmetric FD in bilateral mammograms using a method based on the actual composition of the breast. In initial experiments, our method shows a promising potential for quantifying breast asymmetry with respect to the laterality of cancer. It works very well in all BIRADS classes, including BIRADS-D.