Development and Evaluation of Artificial Intelligence Tools to Estimate Volumetric Breast Density from Processed 2D Mammograms

Objectives Artificial intelligence (AI) has shown promise for estimating volumetric breast density values from processed, “for presentation”, mammograms. However, previous evaluations have typically used small datasets or focused on a single vendor. In this study we aimed to improve volumetric breast density estimation from processed mammograms for the three main UK vendors with a combination of improved training methods and the utilisation of up-to-date data from the large OPTIMAM Mammography Image Database (OMI-DB). Methods Paired processed/unprocessed mammograms were obtained from OMI-DB. Ground-truth, image-level density values were calculated by passing unprocessed images through a commercial density estimation tool. AI tools, comprising feed-forward convolution neural networks, were then trained to reproduce these values from the corresponding processed mammograms. Results Patient-level AI predictions for volumetric breast density demonstrated strong correlation with ground truth values derived from unprocessed image counterparts (r = 0.954-0.976). Models trained on less prevalent manufacturers performed worse (r = 0.954 compared to 0.976 for the most prevalent manufacturer), highlighting the importance of collecting larger training datasets in future. Error levels were higher in patients with dense breasts. Model performance was generally consistent across screening sites but correlated with patient age, possibly due to the correlation of age and breast density. Conclusions The presented models demonstrated good performance overall and were generally consistent across screening sites. Advances in knowledge The presented AI tools provide a means of estimating breast density from processed mammograms, enabling further research into breast cancer epidemiology and risk where only processed mammograms are available.