Elizabeth Ann Rafferty MD, Presenter: Research grant, Hologic, Inc

Andrew Paul Smith PhD, Abstract Co-Author: Employee, Hologic, Inc

Loren Thomas Niklason PhD, Abstract Co-Author: Employee, Hologic, Inc Patent holder, Hologic, Inc Patent holder, Breast Tomosynthesis

Compare three methods of estimating breast density. These methods included BI-RADS density scores for full field digital mammography (FFDM) and breast tomosynthesis. In addition, volumetric density based on x-ray transmission of the breast was calculated.

Breast density of 310 subjects was scored by 15 radiologists. The radiologists scored the breast density using the BI-RADS breast density scale for both FFDM (Hologic Selenia FFDM system) and breast tomosynthesis (Hologic tomosynthesis prototype). For 264 cases the volumetric breast density was also measured using x-ray transmission measurements (Hologic R2 Quantra system). Breast composition was categorized as primarily fatty or dense by each method for each case and the results compared.

The average BI-RADS density scores using FFDM and tomosynthesis were nearly identical. Significant inter-reader variability was observed for both methods. The average standard deviation of radiologists’ BI-RADS scores for individual cases was 0.45 and 0.48 for FFDM and Tomosynthesis, respectively. Therefore the estimation and variability of breast density scoring was nearly identical for FFDM and tomosynthesis. A comparison of volumetric density to radiologists’ BI-RADS scoring demonstrated agreement in 83% of cases scored as dense and in 87% of cases scored as fatty.

Increased breast density has been shown to be associated with increased risk of breast cancer and decreased sensitivity of conventional mammography. Currently the standard method of estimating breast density is the BI-RADS score. This study provides evidence that radiologists’ estimates of breast density scored by the BI-RADS system are similar with FFDM and tomosynthesis, although significant inter-reader variability remains. Computer-based categorization of density also yielded similar density scores while offering the advantage of standardized scoring.

Tomosynthesis and FFDM provide a similar estimation of breast density; volumetric breast density may provide an alternative method of determining breast density.

Rafferty, E, Smith, A, Niklason, L, Comparison of Three Methods of Estimating Breast Density: BI-RADS Density Scores Using Full Field Digital Mammography, BI-RADS Density Scores Using Breast Tomosynthesis, and Volumetric Breast Density.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8016645.html