Diagnostic performance of phase-contrast computed tomography versus digital mammography: A pilot study

Digital mammography (DM) remains the standard for breast cancer screening, but its diagnostic limitations and the discomfort associated with breast compression motivate exploration of alternative imaging technologies. This retrospective pilot study assessed the diagnostic performance of x-ray propagation-based phase-contrast computed tomography (PB-CT) compared with DM at comparable radiation doses and generated parameter estimates to inform the design of future powered diagnostic studies.

Pre-excision screening DM and post-excision breast mastectomy PB-CT images from 30 patients were evaluated. The dataset included malignant, benign, and normal findings. Ten breast radiologists independently reviewed DM and PB-CT images to determine the presence or absence of malignancy and assign a confidence rating. Diagnostic accuracy was quantified using the area under the receiver operating characteristic curve (AUC), with comparisons performed using the Obuchowski-Rockette method, treating readers and cases as random samples.

Images from 30 patients (mean age, 49 ± 11 years; 29 women) were assessed. The reader-averaged AUCs were 0.924 for PB-CT and 0.906 for DM, resulting in a mean difference of 0.018 [p = 0.67; 95 % CI = (-0.066 to 0.102)].

Results of this small, retrospective pilot study provide support to justify a larger, adequately powered study to determine whether PB-CT provides a non-inferior or superior diagnostic performance compared to DM, while offering true three-dimensional imaging. In addition, this study provides the necessary parameter estimates for sizing such a study.

This pilot study demonstrates the feasibility of compression-free, three-dimensional breast imaging using PB-CT at clinically relevant radiation doses. If future studies confirm a diagnostic benefit, such an approach could broaden breast-imaging options and potentially improve patient outcomes.