Prompting is utilised in CAD systems to draw attention to regions of potential abnormality within screening mammograms. The benefit of such systems is under debate. Our previous research found that radiologists’ visual search patterns were significantly altered when mammographic prompts were displayed. Visual attention concentrated upon prompted areas, with significantly less attention to unprompted regions. Additionally, prompts caused a reduction in the amount of bi-lateral visual comparisons between the two breasts. Current CAD systems use a variety of prompts (e.g. circle and triangle) that appear incongruous to the mammogram and may inadvertently detract attention from unprompted regions. The aim of this experiment was to determine whether attentional focus would continue when using subtle prompts, without resulting in the insufficient search of unprompted areas. A series of paired medio lateral-oblique view mammographic cases were presented to participants on a monitor. Images were presented as "unprompted" and "prompted"- using various methods to highlight potentially abnormal areas. These included typical prompt shapes and also more novel prompts (e.g. altered brightness and colour). Participants were instructed to scan the images as they normally would when screening for abnormalities and to indicate their confidence that an abnormality was present, using a five-point scale. Eye movements were recorded during the task. Results demonstrated that visual attention was drawn to prompted regions. However, the potentially negative influence of prompts upon normal visual search patterns within mammograms was found to be less pronounced in conditions containing novel prompts. By comparing differing prompts during screening it was possible to establish their consequent impact upon visual search patterns. This research contributes to the establishment of optimal prompt displays in soft copy systems.
A series of studies were carried out to determine the accuracy of transcribing feature locations in a 'reference’ mammogram to a scaled, and sometimes simplified 'copy’ of the same image. A computer monitor displayed two images of a mammogram. The reference image of the mammogram was presented at 256 colors (greyscale) and, adjacent to this, the copy image was presented with height and width scaled to 0.25, 0.50 or 0.75 of the original, and in one of four forms: blank image, outline, 16 colour palette, and 256 color palette. Participants were required to locate a target on the reference image and indicate its location on the copy image. Results demonstrated accuracy in transcription of target location increased with enhanced image detail and scale. Consequently, it is possible to determine which image characteristics are important in situations where a small representational image is used to record patient information, such as the user interface for a tablet device used to record breast screening decisions.