# A Comparative Analysis of Digital Mammography and Digital Breast Tomosynthesis in Japanese Women

## TL;DR

This study compares digital mammography and digital breast tomosynthesis in Japanese women, finding that tomosynthesis improves accuracy for dense breasts but increases reading time.

## Contribution

The study introduces a novel focus on breast density, reader experience, and workflow efficiency in Japanese women.

## Key findings

- DM+DBT improved diagnostic accuracy for dense breasts in screening settings (AUC 0.766 vs. 0.684).
- Reading times increased significantly with DBT (71.3-113.8 seconds vs. 32.5-82.5 seconds).
- Inter-reader agreement was higher with DM+DBT but not statistically significant.

## Abstract

Introduction

Digital breast tomosynthesis (DBT) addresses the limitations of digital mammography (DM). While DM+DBT is gradually replacing DM in the United States and other Western countries, its adoption in Japan has been limited. This study assessed and compared the diagnostic performance of DM and DM+DBT, with a novel focus on breast density, reader experience, and workflow efficiency in Japanese women who underwent examinations during our early experience shortly after the introduction of DBT.

Methods

A retrospective review of 48 patients (19 with breast cancer and 29 with benign lesions) who underwent both DM and DBT at Jyoban Hospital was conducted. Five readers (two physicians, one medical resident, and two radiologic technologists) assessed the images. Diagnostic accuracy was evaluated using receiver operating characteristic (ROC) curve analysis for breast density and reader experience in both screening and clinical settings. Inter-reader agreement and reading times were assessed, with paired t-tests used to analyze differences in reading times.

Results

DM+DBT achieved higher inter-reader agreement than DM (Kappa: 0.708, 95% CI: 0.567-0.849 vs. 0.661, 95% CI: 0.511-0.811), though this difference was not statistically significant (p = 0.653). In screening settings, DM+DBT significantly improved the area under the curve (AUC; 0.750, 95% CI: 0.717-0.784 vs. 0.709, 95% CI: 0.675-0.743; p = 0.005); in clinical settings, the increase was not significant (0.878, 95% CI: 0.834-0.921 vs. 0.844, 95% CI: 0.797-0.891; p = 0.153). For dense breasts, AUC improved notably with DBT (screening: 0.766, 95% CI: 0.699-0.833 vs. 0.684, 95% CI: 0.612-0.756; p = 0.007; clinical: 0.936, 95% CI: 0.883-0.990 vs. 0.827, 95% CI: 0.740-0.914; p = 0.023), but no significant differences were observed in non-dense breasts. All readers improved with DBT, except the medical resident. Reading times increased significantly, from 32.5-82.5 seconds (DM) to 71.3-113.8 seconds (DM+DBT) (p = 0.006).

Conclusion

DM+DBT improves diagnostic accuracy, particularly for dense breasts in Japanese women, but longer reading times and reader experience may limit its widespread adoption.