Abstracts of the Royal College of Radiologists Breast Group Annual Scientific Meeting. Belfast, Northern Ireland. November 1-3, 2009.

Introduction

Digital breast tomosynthesis (DBT) may improve the accuracy of mammography by enabling visual separation of overlapping tissues (Andersson et al. 2008, Poplack et al. 2007).

Methods

Following local research ethics approval, all women attending the assessment clinic for evaluation of a mammographic abnormality found on routine screening (film-screen) were invited to take part in the study subject to informed consent. Participants underwent bilateral two-view two-dimensional (2D) digital mammography and bilateral two-view DBT. Mammography scores using the RCR Breast Group classification were sequentially obtained for the screening mammogram, 2D digital and DBT, and these were each compared with the final assessment outcome.

Results

Ninety-one percent of eligible women participated. Results from the first 300 participants are presented in Table 1 below.

Table 1

	Imaging score	Screening mammogram	2D digital mammogram	DBT
Assessment outcome = normal or benign (n = 238)	M1 or M2	44 (18.4%)	130 (54.6%)	174 (73.1%)
Assessment outcome = malignant (n = 62)	M5	22 (35.4%)	25 (40.3%)	33 (53.2%)

Indeterminate scores (M3) were assigned to 197 (65.7%) screening mammograms, 108 (36.0%) 2D digital mammograms and 62 (20.7%) DBT.

Kappa coefficients for agreement of each imaging method with final assessment outcome were calculated. Screening mammograms had the lowest agreement with the final outcome (Kappa = 0.02; P = 0.22), 2D digital mammography was better (Kappa = 0.26; P = 0.0000) and DBT had the highest score (Kappa = 0.37; P = 0.0000).

Conclusion

The preliminary results of this ongoing study show that DBT increases the diagnostic confidence of the radiologist. This supports the need for a larger multicentre study.