Breast tomosynthesis and digital mammography: a comparison of diagnostic accuracy

Abstract

Objective: Our aim was to compare the ability of radiologists to detect breast cancers using one-view breast tomosynthesis (BT) and two-view digital mammography (DM) in an enriched population of diseased patients and benign and/or healthy patients.

Methods: All participants gave informed consent. The BT and DM examinations were performed with about the same average glandular dose to the breast. The study population comprised patients with subtle signs of malignancy seen on DM and/or ultrasonography. Ground truth was established by pathology, needle biopsy and/or by 1-year follow-up by mammography, which retrospectively resulted in 89 diseased breasts (1 breast per patient) with 95 malignant lesions and 96 healthy or benign breasts. Two experienced radiologists, who were not participants in the study, determined the locations of the malignant lesions. Five radiologists, experienced in mammography, interpreted the cases independently in a free-response study. The data were analysed by the receiver operating characteristic (ROC) and jackknife alternative free-response ROC (JAFROC) methods, regarding both readers and cases as random effects.

Results: The diagnostic accuracy of BT was significantly better than that of DM (JAFROC: p=0.0031, ROC: p=0.0415). The average sensitivity of BT was higher than that of DM (∼90% vs ∼79%; 95% confidence interval of difference: 0.036, 0.108) while the average false-positive fraction was not significantly different (95% confidence interval of difference: -0.117, 0.010).

Conclusion: The diagnostic accuracy of BT was superior to DM in an enriched population.

Figure 1

(a) The average alternative free-response receiver operating characteristic curves: breast tomosynthesis (BT)=0.809; digital mammography (DM)=0.706; Δ_BT–DM=0.103. (b) The average receiver operating characteristic curves: BT=0.860; DM=0.766; Δ_BT–DM=0.094. FPF, false-positive fraction; LLF, lesion localisation, fraction; TPF, true-positive fraction.

Figure 2

(a) The distribution of breast cancers by histopathology of 89 diseased cases with a total of 95 breast cancers. (b) The reader-averaged true-positive fraction (TPF; sensitivity) by histopathology with 95% confidence intervals for breast tomosynthesis and digital mammography. DCIS, ductal carcinoma in situ; IDC, invasive ductal carcinoma; ILC, invasive lobular carcinoma; Tub, tubular carcinoma.

Figure 3

(a) Breast tomosynthesis (BT) mediolateral oblique (MLO) view (one-view BT), (b) digital mammography (DM) MLO view and (c) DM craniocaudal (CC) view (two-view DM). (d, e) Close-ups of (a, b). A 69-year-old female with a 15-mm (diameter) spiculated tumour, invasive ductal carcinoma grade 2. Owing to its juxtathoracic position, the tumour was not included in the CC view (c). The tumour, indicated by the arrow in (a, d), was detected on one-view BT by all readers, while on two-view DM (b, c) it was not detected by any of the readers.

Figure 4

(a) Breast tomosynthesis (BT) mediolateral oblique (MLO) view (one-view BT), (b) digital mammography (DM) MLO view and (c) DM craniocaudal (CC) view (two-view DM). (d–f) Close-ups of (a–c). A 79-year-old female with a 10-mm (diameter) spiculated tumour (arrow in a and d), invasive ductal carcinoma grade 3. The tumour was detected on one-view BT by 4/5 readers, while on two-view DM (b, c) the tumour was undetected by all readers.