Breast cancer screening is an important part of routine medical care for women around the world. The modern standard screening method is Full Field Digital Mammography (FFDM) in which two- dimensional, digital x-ray images are created of the entire thickness of the breast. Digital Breast Tomosynthesis (DBT) is an important advance that creates a 3D volume of images, consisting of a set of x-ray slices through the breast. DBT has been shown to improve accuracy - both the sensitivity and specificity - of breast cancer screening over FFDM alone, but clinical adoption has been relatively slow, in part because exams with DBT take significantly longer to interpret than do FFDM alone. The proposed studies will use medical image perception experiments to improve search strategies for DBT images, with the goal of increasing the speed and accuracy of breast cancer screening. There are three aims.
Aim 1 : To examine the pattern of eye movements and their relationship to errors when radiologists read DBT images in order to determine which search strategies are significantly faster and/or more accurate than others. Eye movements will be measured while three groups of radiologists read DBT: radiologists prior to DBT training, just after DBT training, and DBT experts. These data will reveal whether the strategies, taught by experts, are the same as the strategies used by experts in practice and whether, after training, trainees do what the experts recommend.
Aim 2 : Typically, a radiologist would use the FFDM image to guide subsequent search of DBT images.
In Aim 2, this will be reversed. The hypothesis is that an initial preview of a DBT ?movie? will improve speed and/or accuracy of breast cancer screening by guiding the reader to important loci in the FFDM image and by aiding further examination of the DBT images.
Aim 3 : Compared to FFDM, DBT greatly increases the number of images that are available to be searched. It would be extremely time consuming and unnecessary to scrutinize every pixel of every slice. How many regions does a reader need to fixate upon in order to be reasonably sure that some sign of cancer, if present, will attract attention? To answer this question, we need to know the distance away from fixation at which different signs of cancer can be detected. A combination of studies with expert and non-expert observers will enable us to measure these distances. Combined with the eye tracking data from Aim 1, these data can be used to determine if error rates can be reduced by training radiologists to use specific search patterns. This program of research will yield low-cost interventions that can improve the use of DBT and, thus, enhance the life-saving effectiveness of breast cancer screening
Digital Breast Tomosynthesis (DBT) is a new 3-dimensional breast cancer imaging modality that has better sensitivity and specificity than 2-dimensional digital mammography. Reading the tomosynthesis images requires that radiologists develop new search strategies that may differ from their optimized 2-D strategy for Full Field Digital Mammography (FFDM), so that they can read efficiently and accurately. The medical image perception experiments in this proposal will address the lack of knowledge about optimal search strategies and will lead to recommendations for low- cost interventions that can improve the use of DBT and, thus, the effectiveness of breast cancer screening.
