Interreader scoring variability in an observer study using dual-modality imaging for breast cancer detection in women with dense breasts.

RATIONALE AND OBJECTIVES

To evaluate variability in the clinical assessment of breast images, we evaluated scoring behavior of radiologists in a retrospective reader study combining x-ray mammography (XRM) and three-dimensional automated breast ultrasound (ABUS) for breast cancer detection in women with dense breasts.

METHODS

The study involved 17 breast radiologists in a sequential study design with readers first interpreting XRM-alone followed by an interpretation of combined XRM + ABUS. Each interpretation included a forced Breast Imaging Reporting and Data System scale and a likelihood that the woman had breast cancer. The analysis included 164 asymptomatic patients, including 31 breast cancer patients, with dense breasts and a negative screening XRM. Of interest were interreader scoring variability for XRM-alone, XRM + ABUS, and the sequential effect. In addition, a simulated double reading by pairs of readers of XRM + ABUS was investigated. Performance analysis included receiver operating characteristic analysis, percentile analysis, and κ statistics. Bootstrapping was used to determine statistical significance.

RESULTS

The median change in area under the receiver operating characteristic curve after ABUS interpretation was 0.12 (range 0.04-0.19). Reader agreement was fair with the median interreader κ being 0.26 (0.05-0.48) for XRM-alone and 0.34 (0.11-0.55) for XRM + ABUS (95% confidence interval for the difference in κ, 0.06-0.11). Simulated double reading of XRM + ABUS demonstrated tradeoffs in sensitivity and specificity, but conservative simulated double reading resulted in a significant improvement in both sensitivity (16.7%) and specificity (7.6%) with respect to XRM-alone.

CONCLUSION

A modest, but statistically significant, increase in interreader agreement was observed after interpretation of ABUS.