Mammographic density measurement: A comparison of automated volumetric density measurement to BIRADS

The aim of this study is to compare mammographic breast density assessment with automated volumetric software with Breast Imaging Reporting and Data System (BIRADS) categorization by radiologists on two imaging systems. A data set of 120 mammograms was classified by twenty American Board of Radiology (ABR) Examiners. The mammograms were of 20 women (mean age, 60 years; range, 42-89 years). These women were image twice once with GE system and the following year with Hologic system. These images also had their volumetric density classified by using Volpara Density Grade (VDG). The radiologists were asked to estimate the mammographic density according to BIRADS categories (1- 4). There was a moderate agreement between VDG classification and radiologist BIRADS density shown with Cohen's Kappa (K=0.45; p<0.001). Radiologists estimated percentage density to be lower by an average of 0.37, the radiologist's BIRADS having a mean of 2.13 and the mean VDG higher at 2.50 (t = -11.99; p<0.001). VDG and radiologist's BIRADS showed a positive strong correlation (r=0.84; p<0.001). Radiologist BIRADS and VDG AvBD% also showed a strong positive correlation (r=0.86; p<0.001). There was a large spread of radiologist's BIRADS categories for each of the VDG AvBD% classifications. Using Volpara, the Hologic system showed a higher meanAvBD% (10.02 vs. 9.97). However using BIRADS the Hologic systems showed a lower mean (2.05 vs. 2.21). Automated systems demonstrated higher internal validity. The results demonstrated a moderate agreement and a strong correlation between VDG classification and radiologist BIRADS density assessment.