Contrast-Enhanced Mammography: Does Image Acquisition Time and Projection Order Matter?

To determine reader preference for image order and thus, by inference, image timing after contrast administration that maximizes cancer visualization on contrast-enhanced mammography (CEM).

This IRB-approved reader study includes consecutive CEMs performed for research or clinical care in patients before a diagnosis of unifocal breast cancer, where the cancer was seen on both craniocaudal (CC) and mediolateral oblique (MLO) recombined images. All CEMs started with the side containing cancer and alternated with the nonaffected side of the same projection. From 2016 to 2018, CC projection was performed first (group 1), and from 2019 to 2020, the MLO projection was performed first (group 2). Five readers evaluated cases for background parenchymal enhancement (BPE) and lesion type. Readers assessed cancer visibility, confidence in margins, and cancer conspicuity using a 5-point Likert scale. Contrast-to-noise (CNR) measurements were also taken.

Seventy-eight female patients were included. Group 1 (CC-first) included 40 patients (51%) and group 2 (MLO-first) included 38 patients (49%). Mean age differed between groups by 5 years (P = .031), otherwise there were no differences in group characteristics. There was an overall preference for earlier-obtained images for cancer visibility, confidence in margins, and lesion conspicuity against BPE (P < .001) and preference for CC projection for lesion conspicuity (P = .045). In 35 instances (35/390, 9%), an individual reader reported a different lesion type on images obtained later, with a majority (28/35, 80%) reporting a less discernible lesion on later-obtained imaging (eg, mass changed to nonmass enhancement).

Our study shows significant reader preference for cancer characteristic evaluation of CEM performed at earlier time points.