Comparison of standard reading and computer aided diagnosis (CAD) on a proficiency test of screening mammography.

PURPOSE: To evaluate the role of computer aided diagnosis (CAD) to improve screening mammograms interpretation. MATERIALS AND METHODS: Six radiologists underwent a screening mammography proficiency test first by conventional, then by CAD assisted reading. Sensitivity and recall rate at conventional and CAD reading were compared. Independent conventional double reading was simulated (15 pair combinations) and compared to single CAD reading. RESULTS: CAD marked 31 of 32 cancers (case-based sensitivity=96.8%). On a film and lesion basis, CAD identified 31 of 32 (96.8%) malignant calcifications and 29 of 42 (69.0%) malignant opacities, the only cancer not identified by CAD being depicted as an isolated opacity. CAD marked 348 areas (153 microcalcifications and 195 opacities) in 88 of 108 non cancer cases, with a case-based specificity of 18.5% (20/108). Considering all six readings, cancer was identified in 164 or 174 of 192 readings (85.4 vs 90.6%, c2 2.03, df=1, p=0.15) and recalls of non-cancer cases were 108 or 159 of 648 readings (16.6 vs 24.5%, c2 11.7, df=1, p<0.001) at conventional or CAD reading, respectively. CAD reading (average of 6 readings, 192 cancer, 648 non-cancer readings) was slightly, non significantly less sensitive (sensitivity 90.6 vs 92.9%, c2 0.73, df=1, p=0.39) and slightly, but not significantly more specific (recall rate 24.5 vs 26.1%, c2 0.56, df=1, p=0.45) as compared to simulated independent double reading (average of 15 combinations, 480 cancer, 1620 non-cancer readings). CONCLUSION: CAD seems to allow for a limited absolute increase (+5.2%) in sensitivity and for a limited absolute increase (+7.9%) in recall rate, the latter difference only reaching statistical significance. CAD reading showed no significant difference in diagnostic accuracy as compared to conventional (simulated) double reading, although further studies are needed to confirm it as possible alternative to double reading in the current screening practice.