Breast cancer detection in digital breast tomosynthesis and digital mammography - A side-by-side review of discrepant cases.

Objective: To analyse discrepant breast cancer detection in digital breast tomosynthesis (DBT) and digital mammography (DM). Methods: From a previous detection study comparing DBT and DM, 26 discrepant cases were extracted, 19 detected by DBT only and 7 by DM only. An expert panel of 3 radiologists reviewed these cases and documented level of discrepancy, lesion visibility, radiographic pattern, lesion conspicuity and assessed the reason for non-detection. Differences between groups were tested using the Wilcoxon Rank Sum test, the Kruskal-Wallis test and visual grading characteristics. Results: The proportion of lesion periphery in fatty tissue was statistically significantly larger, and there were significantly more spiculated masses in DBT compared to DM in the DBT Only group (p=0.018; p=0.015). The main reasons for missing a lesion were poor lesion visibility when using DM and interpretative error when using DBT. Conclusion: Lesion visualization is superior with DBT, particularly of spiculated tumours. A major reason for non-detection in DBT seems to be interpretative error, which may be due to lack of experience.