Validation of Breast Density Measurement Using Dual Energy Mammography: A Post Mortem Study
J L Ducote*, H Ding, M Klopfer, S Molloi, University of California, Irvine, CATH-A-217BCD-7 Thursday 8:00:00 AM - 9:55:00 AM Room: 217BCD
Purpose: To validate the use of dual energy mammography for the measurement of breast density in 40 post mortem ex vivo breast tissue samples.
Methods: Twenty pairs of post mortem breast samples (n=40) 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. Dual energy decomposition of the low and high energy images yielded individual pixel measurements of glandular and adipose equivalent material thicknesses. The decomposition was based on a previous calibration with glandular and adipose equivalent phantoms. Breast density (BD) was calculated as the ratio of glandular thickness over the sum total thickness. Each post mortem sample was then analyzed by chemical analysis based on desiccation, trituration and fat extraction to determine the weight and subsequent percent composition of water, lipid and lean (i.e. protein + mineral) contents. The fibroglandular ratio (FGR), a surrogate quantity to breast density, was calculated from the chemical analysis data as the ratio of the total volume of water and lean contents over the sum of all three contents.
Results: Linear relationships between breast density and the water, lipid, and lean contents were all highly correlated. BD and FGR data were related by BD = 1.9 FGR - 50 (r>0.99).
Conclusions: The high correlation between breast composition data determined from images and data determined from chemical analysis serve to validate the use of dual energy mammography as a measurement technique. It is thought that more quantitative means of measuring breast density, like the one proposed here, will help to further enhance its use and utility as a marker and risk factor for the development of breast cancer.