Reversal of the hanging protocol of Contrast Enhanced Mammography leads to similar diagnostic performance yet decreased reading times

Abstract

Objectives: Contrast-enhanced mammography (CEM) was found superior to Full-Field Digital Mammography (FFDM) for breast cancer detection. Current hanging protocols show low-energy (LE, similar to FFDM) images first, followed by recombined (RC) images. However, evidence regarding which hanging protocol leads to the most efficient reading process and highest diagnostic performance is lacking. This study investigates the effects of hanging-protocol ordering on the reading process and diagnostic performance of breast radiologists using eye-tracking methodology. Furthermore, it investigates differences in reading processes and diagnostic performance between LE, RC and FFDM images. Materials and methods: Twenty-seven breast radiologists were randomized into three reading groups: LE–RC (commonly used hangings), RC-LE (reversed hangings) and FFDM. Thirty cases (nine malignant) were used. Fixation count, net dwell time and time-to-first fixation on malignancies as visual search measures were registered by the eye-tracker. Reading time per image was measured. Participants clicked on suspicious lesions to determine sensitivity and specificity. Area-under-the-ROC-curve (AUC) values were calculated. Results: RC-LE scored identical on visual search measures, t(16)= -1.45, p =.17 or higher-p values, decreased reading time with 31%, t(16)= -2.20, p =.04, while scoring similar diagnostic performance compared to LE-RC, t(13.2)= -1.39, p -.20 or higher p-values. The reading process was more efficient on RC compared to LE. Diagnostic performance of CEM was superior to FFDM; F (2,26)= 16.1, p <.001. Average reading time did not differ between the three groups, F (2,25)= 3.15, p =.06. Conclusion: The reversed CEM hanging protocol (RC-LE) scored similar on diagnostic performance compared to LE-RC, while reading time was a third faster. Abnormalities were interpreted quicker on RC images. A RC-LE hanging protocol is therefore recommended for clinical practice and training. Diagnostic performance of CEM was (again) superior to FFDM.