Breast cancer detection in digital breast tomosynthesis and digital mammography-a side-by-side review of discrepant cases

Abstract

Objective: To analyse discrepant breast cancer detection in digital breast tomosynthesis (DBT) and digital mammography (DM).

Methods: From a previous detection study comparing DBT and DM, 26 discrepant cases were extracted, 19 detected by DBT only and 7 by DM only. An expert panel of three radiologists reviewed these cases and documented the level of discrepancy, lesion visibility, radiographic pattern and lesion conspicuity and assessed the reason for non-detection. Differences between groups were tested using the Wilcoxon rank sum test, the Kruskal-Wallis test and visual grading characteristics.

Results: The proportion of lesion periphery in fatty tissue was statistically significantly larger, and there were significantly more spiculated masses in DBT compared with DM in the DBT only group (p = 0.018; p = 0.015). The main reasons for missing a lesion were poor lesion visibility when using DM and interpretative error when using DBT.

Conclusion: Lesion visualization is superior with DBT, particularly of spiculated tumours. A major reason for non-detection in DBT seems to be interpretative error, which may be due to lack of experience.

Advances in knowledge: Our findings suggest that DBT is better than DM in visualizing breast cancer and that non-detection when using DBT is related to interpretative error regarding clearly visible lesions.

Figure 1.

Four examples of breast cancers bordering on tissues with different density. Inserts show estimated proportion of lesion periphery bordering on tissue with pre-dominately fatty attenuation: (a) <25%, (b) 25–50%, (c) 50–75% and (d) >75%.

Figure 2.

Discrepant lesions classified as Breast Imaging Reporting and Data System (BI-RADS) 3, 4 or 5 by all readers in digital breast tomosynthesis (DBT) and classified as BI-RADS 1 or 2 by all readers in digital mammography (DM), with a radiographic pattern of a spiculated mass in DBT but no findings in concurrent DM. (a) A case of an symptomatic 76-year-old female with a 10-mm invasive lobular carcinoma, grade 2. (b) A case of an asymptomatic 49-year-old female with a 10-mm invasive tubular carcinoma, grade 1. (c) A case of a symptomatic 66-year-old female with a 15-mm invasive ductal carcinoma, grade 1. (d) A case of a 45-year-old female with a palpable mass, in whom histology showed an 18-mm invasive ductal carcinoma, grade 1.

Figure 3.

Cancers classified as Breast Imaging Reporting and Data System (BI-RADS) 3, 4 or 5 in digital mammography (DM) and classified as BI-RADS 1 or 2 in digital breast tomosynthesis (DBT) by at least two readers, most likely because of interpretative error. (a) A case of a 59-year-old female with a cluster of microcalcifications in DBT and DM, classified as BI-RADS 3, 4 or 5 by four readers in DM and classified as BI-RADS 1 or 2 by two readers in DBT. Histology showed a 45 × 25-mm ductal carcinoma in situ, grade 3. (b) A case of a 63-year-old female with a spiculated lesion in DBT and DM, classified as BI-RADS 3, 4 or 5 by all readers in DM and classified as BI-RADS 1 or 2 by two readers in DBT. The lesion was deemed to be less conspicuous in DBT than in DM, but still clearly visible. Microscopy revealed a 10-mm invasive tubular carcinoma, grade 1. (c) A case of a 66-year-old female with a spiculated, retromamillary lesion in DBT and DM craniocaudal (CC) view, classified as BI-RADS 3, 4 or 5 by all readers in DM and classified as BI-RADS 1 or 2 by two readers in DBT. Microscopy revealed a 10-mm invasive ductal carcinoma, grade 2. (d) A case of a 50-year-old female with architectural distortion in DBT and DM mediolateral oblique view, but without any findings in the CC view, classified as BI-RADS 1 or 2 by three readers in both DBT and DM. Histology showed a large multicentric invasive lobular carcinoma within two areas (90 × 40 mm and 10 × 5 mm). MLO, mediolateral oblique.

Figure 4.

A 62-year-old female with a spiculated lesion in digital breast tomosynthesis (DBT) and digital mammography (DM) images, classified as Breast Imaging Reporting and Data System (BI-RADS) 3, 4 or 5 by all readers in DM but classified as BI-RADS 1 or 2 by four readers in DBT, most likely because of uncharacteristic radiographic appearance. Histology showed a 9-mm invasive ductal carcinoma, grade 1. It was deemed to be equally conspicuous in both DM and DBT, but of all the discrepant cases, it was still the most difficult cancer to detect in DBT. This could be explained by the perilesional breast parenchyma, which was organized in coarse bundles, making it more difficult for the lesion to stand out from the background. CC, craniocaudal; MLO, mediolateral oblique.