Sabee Y. Molloi PhD, Presenter: Nothing to Disclose

Huanjun Ding, Abstract Co-Author: Nothing to Disclose

Justin Ducote, Abstract Co-Author: Nothing to Disclose

Michael Klopfer, Abstract Co-Author: Nothing to Disclose

Stephen Albert Feig MD, Abstract Co-Author: Nothing to Disclose

Volumetric breast density (VBD) techniques based on standard mammograms require estimation of breast thickness, which is difficult to accurately measure. By comparison, calculation of VBD using dual energy mammography does not require measurement of breast thickness. The purpose of this study is the in-vivo validation of VBD measurement with dual energy mammography using chemical analysis as the gold standard. Comparisons were also made with visual assessment and different image segmentation techniques.

40 postmortem breasts were imaged with a full field digital mammography system. Low energy images were acquired at 28 kVp with a 50 μm rhodium filter at 60 mAs. High energy images were acquired at 49 kVp with a 300 μm copper filter at 30 mAs. Measurements of glandular and adipose tissue thicknesses for each pixel were obtained using dual energy decomposition based on previous calibrations with glandular and adipose equivalent phantoms. VBD was calculated as the ratio of glandular thickness over the total thickness. Areal breast density measurements were also made using standard image thresholding and Fuzzy k-mean clustering techniques. Furthermore, four-category BI-RADS density rankings were independently assigned by two radiologists. As a gold standard, each postmortem breast was chemically decomposed into water, lipid and protein. The fibroglandular ratio (FGR) was calculated from the chemical analysis data as the volumetric ratio of the sum of water and protein contents over the total volume. Correlations between FGR and breast densities estimated from all four methods were analyzed individually using linear regression.

Large inter-observer variation was found in breast density evaluation using BI-RADS and single threshold segmentation. When compared to the results of chemical decomposition as the gold standard, the Pearson correlation coefficients increased monotonically in order of BI-RADS ranking (0.80), standard single threshold segmentation (0.83), Fuzzy k-mean clustering (0.85), and dual energy mammography (0.99).

The results indicate that breast density can be accurately measured using dual energy mammography. This can potentially enhance the significance of breast density in breast cancer risk models.

An accurate quantification of volumetric breast density (VBD) is crucial for its potential application to breast cancer risk models.

Molloi, S, Ding, H, Ducote, J, Klopfer, M, Feig, S, Quantification of Volumetric Breast Density Using Dual Energy Mammography.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12043673.html