Mammographic density measurements are not affected by mammography system

Abstract

Mammographic density (MD) is a significant risk factor for breast cancer and has been shown to reduce the sensitivity of mammography screening. Knowledge of a woman's density can be used to predict her risk of developing breast cancer and personalize her imaging pathway. However, measurement of breast density has proven to be troublesome with wide variations in density recorded using radiologists' visual Breast Imaging Reporting and Data System (BIRADS). Several automated methods for assessing breast density have been proposed, each with their own source of measurement error. The use of differing mammographic imaging systems further complicates MD measurement, especially for the same women imaged over time. The purpose of this study was to investigate whether having a mammogram on differing manufacturer's equipment affects a woman's MD measurement. Raw mammographic images were acquired on two mammography imaging systems (General Electric and Hologic) one year apart and processed using VolparaDensity™ to obtain the Volpara Density Grade (VDG) and average volumetric breast density percentage (AvBD%). Visual BIRADS scores were also obtained from 20 expert readers. BIRADS scores for both systems showed strong positive correlation ([Formula: see text]; [Formula: see text]), while the VDG ([Formula: see text]; [Formula: see text]) and AvBD% ([Formula: see text]; [Formula: see text]) showed stronger positive correlations. Substantial agreement was shown between the systems for BIRADS ([Formula: see text]; [Formula: see text]), however, the systems demonstrated an almost perfect agreement for VDG ([Formula: see text]; [Formula: see text]).

Keywords: Breast Imaging Reporting and Data System; General Electric; Hologic; Volpara; mammographic density.

Fig. 1

A scatter plot demonstrating BIRADS correlation for GE versus Hologic imaging systems. The systems showed strong positive correlation ($\rho =0.904$; $p<0.001$). The size of the dot indicates the number of data points it contains.

Fig. 2

A scatter plot demonstrating VDG correlation for GE versus hologic imaging systems. The systems showed stronger positive correlation ($\rho =0.978$; $p<0.001$) for VDG than BIRADS. The size of the dot indicates the number of data points it contains.

Fig. 3

A scatter plot demonstrating AvBD% correlation for GE versus Hologic imaging systems. The systems showed stronger positive correlation ($\rho =0.973$; $p<0.001$) for AvBD% than BIRADS. The size of the dot indicates the number of data points it contains.