20 September 2020
Lång, K., Dustler, M., Dahlblom, V. et al.
Identifying normal mammograms in a large screening population using artificial intelligence
Lång K, Dustler M, Dahlblom V, Åkesson A, Andersson I, Zackrisson S.
To evaluate the potential of artificial intelligence (AI) to identify normal mammograms in a screening population.
In this retrospective study, 9581 double-read mammography screening exams including 68 screen-detected cancers and 187 false positives, a subcohort of the prospective population-based Malmö Breast Tomosynthesis Screening Trial, were analysed with a deep learning–based AI system. The AI system categorises mammograms with a cancer risk score increasing from 1 to 10. The effect on cancer detection and false positives of excluding mammograms below different AI risk thresholds from reading by radiologists was investigated. A panel of three breast radiologists assessed the radiographic appearance, type, and visibility of screen-detected cancers assigned low-risk scores (≤5). The reduction of normal exams, cancers, and false positives for the different thresholds was presented with 95% confidence intervals (CI).
If mammograms scored 1 and 2 were excluded from screen-reading, 1829 (19.1%; 95% CI 18.3–19.9) exams could be removed, including 10 (5.3%; 95% CI 2.1–8.6) false positives but no cancers. In total, 5082 (53.0%; 95% CI 52.0–54.0) exams, including 7 (10.3%; 95% CI 3.1–17.5) cancers and 52 (27.8%; 95% CI 21.4–34.2) false positives, had low-risk scores. All, except one, of the seven screen-detected cancers with low-risk scores were judged to be clearly visible.
The evaluated AI system can correctly identify a proportion of a screening population as cancer-free and also reduce false positives. Thus, AI has the potential to improve mammography screening efficiency.
• Retrospective study showed that AI can identify a proportion of mammograms as normal in a screening population.
• Excluding normal exams from screening using AI can reduce false positives.