Evaluation of computer-aided detection (CAD) devices.

We present a review of three major UK studies of computer-aided detection (CAD) for mammography. A short account of the motivation, methods and results is given for each of the three. A number of conclusions are drawn, particularly about the merits and difficulties of research in the field. The first two studies measured the impact of CAD on the sensitivity and specificity of film readers interpreting cases with known outcomes displayed on rollers with an artificially high frequency of cancers. In the first study 50 film readers each read 180 cases, including 60 cancers (40 screen-detected and 20 interval). In the second study 35 film readers viewed 120 cases including 44 cancers, of which 40 were selected to be difficult cases that CAD prompted correctly. The third study was carried out prospectively. 6111 films were independently double read by film readers who recorded a judgement before and after viewing CAD prompts. In addition to this, intraobserver measure of the impact of CAD, we compared the cancer detection rate in these cases with that in 1339 cases read over the same period without the benefit of CAD. None of the three studies showed a statistically significant effect attributable to CAD. There is evidence that a high proportion of missed cancers are prompted and that "emphasised" prompts, which have a greater positive predictive value, have a stronger impact on decision-making that other prompts.