Comparison of readers' detection of right-sided and left-sided breast cancers and microcalcifications.

Introduction: Aim of this study was to determine if there is a statistically and clinically significant difference in diagnostic performance (cancer diagnosis) and perceptual performance (microcalcification detection) when detecting left-sided or right-sided breast cancers and microcalcifications.

Methods: Eight radiologist readers (8-20 years experience in radiology, five current BreastScreen readers) read a set of 100 digital mammograms (23/100 had proven malignancies and 52/100 had confirmed microcalcifications) for three reads (random case order in each read). The same mammograms were presented on two reads, serving as the baseline reads. The data from these reads were used to calculate intra-observer variability (presented in an earlier study). The experimental read consisted of left-right mirror images of the original mammograms. In each read, the radiologists were requested to 'clear' or 'call-back' cases and to indicate if any microcalcifications (benign and malignant) were present on the mammograms. Reading conditions were standardised.

Results: Comparison of intra-reader performance difference for left-sided versus right-sided breast cancers and microcalcifications with intra-observer variability for breast cancer diagnosis and microcalcification detection, respectively, revealed no clinically significant difference between left-sided and right-sided detections. Per-case analysis showed more left-sided breast cancers and microcalcifications correctly detected. This left-right difference in detection did not reach statistical significance, P-value of 0.28 for cancer diagnosis and 0.74 for microcalcification detection.

Conclusion: There is no statistically or clinically significant difference between left-sided and right-sided breast cancer diagnosis and microcalcification detection in a group of experienced radiologists. Individual reading patterns do not affect detection rates of left-sided and right-sided cancers and microcalcifications.