ABSTRACT
Early diagnosis improves prognosis, and this can be augmented in association with appropriate therapy, for example, drugs such as tamoxifen (Nolvadex®). Based on this observation, many countries, including most European countries, Australia, and New Zealand, now have government-funded, population-based screening programs in which asymptomatic women within a certain age range (e.g., 50-75 in the United Kingdom) are invited every 2 or 3 years to have a
Sir Michael Brady, Ralph Highnam, and Nico Karssemeijer
5.1 Introduction 75 5.2 Recognition of the Importance of Breast Density 77 5.3 Measuring Breast Density from Images 80
5.3.1 Absolute Physics Models of Image Acquisition 80 5.3.2 3D from 2D Using a Calibration Device 83 5.3.3 Relative Physics Model of Image Acquisition 84
5.4 Experiments on Measuring Breast Density Using Relative Physics Model 85 5.4.1 Phantom Study 85 5.4.2 Dierent X-Ray Detectors 85 5.4.3 Volumetric Density vs. BI-RADS 86 5.4.4 Volumetric Density on Dierent Manufacturer’s Mammography Units 87 5.4.5 Comparison of Volumetric Density Estimated Using Commercial Software
with at Estimated from MRI 87 5.4.6 Kopans’s Reader Study 87 5.4.7 Population Breast Density Change over Time 88
5.5 Direct 3D Estimation of the Volume of Breast Density 88 5.5.1 Breast CT 88 5.5.2 Breast MRI 89 5.5.3 Breast Ultrasound 90
5.6 Discussion 90 Acknowledgments 91 References 91
mammogram (x-ray image of the tightly compressed breast). In the United States, even without the centralized screening programs, there are still 8,700 breast imaging centers staed by just 2,500 specialist mammography radiologists, augmented by 15,000 general radiologists, who use mammography to screen 43 million women each year. Currently, every screening program is based on mammography since it optimizes the trade-o between sensitivity, specicity, and cost, including the time to image the woman. Screening is proven to save lives. For example, the UK Breast Screening Programme reports that “For every 400 women screened regularly by the NHS Breast Screening Programme over a 10 year period, one woman fewer will die from breast cancer than would have died without screening.” e current NHS Breast Screening Programme saves an estimated 1400 lives each year in England (BSP61 2006). However, mammographic screening is far from perfect: only 20% of all diagnosed breast cancers are caught by screening. Of the cancers that are present at screening, 20% are missed, and 50%–80% of biopsies nd only benign disease. Why is this so?
