Prospective trial comparing full-field digital mammography (FFDM) versus combined FFDM and tomosynthesis in a population-based screening programme using independent double reading with arbitration

Abstract

Objectives: To compare double readings when interpreting full field digital mammography (2D) and tomosynthesis (3D) during mammographic screening.

Methods: A prospective, Ethical Committee approved screening study is underway. During the first year 12,621 consenting women underwent both 2D and 3D imaging. Each examination was independently interpreted by four radiologists under four reading modes: Arm A-2D; Arm B-2D + CAD; Arm C-2D + 3D; Arm D-synthesised 2D + 3D. Examinations with a positive score by at least one reader were discussed at an arbitration meeting before a final management decision. Paired double reading of 2D (Arm A + B) and 2D + 3D (Arm C + D) were analysed. Performance measures were compared using generalised linear mixed models, accounting for inter-reader performance heterogeneity (P < 0.05).

Results: Pre-arbitration false-positive scores were 10.3 % (1,286/12,501) and 8.5 % (1,057/12,501) for 2D and 2D + 3D, respectively (P < 0.001). Recall rates were 2.9 % (365/12,621) and 3.7 % (463/12,621), respectively (P = 0.005). Cancer detection was 7.1 (90/12,621) and 9.4 (119/12,621) per 1,000 examinations, respectively (30 % increase, P < 0.001); positive predictive values (detected cancer patients per 100 recalls) were 24.7 % and 25.5 %, respectively (P = 0.97). Using 2D + 3D, double-reading radiologists detected 27 additional invasive cancers (P < 0.001).

Conclusion: Double reading of 2D + 3D significantly improves the cancer detection rate in mammography screening.

Key points: • Tomosynthesis-based screening was successfully implemented in a large prospective screening trial. • Double reading of tomosynthesis-based examinations significantly reduced false-positive interpretations. • Double reading of tomosynthesis significantly increased the detection of invasive cancers.

Fig. 1

Flow chart showing the number of women attending the screening programme during the study period, the number of women excluded from analysis and the study material

Fig. 2

Flow chart showing the positive scores, the recalls and the cancers detected in the 2D arm and the combined 2D + 3D (combo mode) for the study population

Fig. 3

A 68-year-old woman. a Right breast cranio-caudal view (2D) shows a non-specific density. Enlargement of the 2D (b) and synthesised 2D (c) shows a suspicious but non-conclusive irregular density. On tomosynthesis (3D) cranio-caudal view, however, a spiculated mass consistent with invasive cancer is clearly seen (d). The cancer was missed by both readers in the 2D arm. Histology revealed an 8-mm invasive lobular carcinoma grade 2

Fig. 4

A 64-year-old woman. a Right breast medio-lateral-oblique view (2D) shows a round benign mass shown in the upper right portion of the marked region, but no suspicious findings. Enlargement of 2D (b) and synthesised 2D (c) does not show any suspicious findings. Tomosynthesis (3D) (d) medio-lateral-oblique view clearly shows a spiculated mass ventro-caudal of the benign round mass and in the centre of the marked region. The cancer was missed by both readers in the 2D arm. Histological examination showed a 6-mm tubular carcinoma