Does Breast Imaging Experience During Residency Translate Into Improved Initial Performance in Digital Breast Tomosynthesis?

A randomized controlled trial of digital breast tomosynthesis versus digital mammography in population-based screening in Bergen: interim analysis of performance indicators from the To-Be trial

Objectives

To describe a randomized controlled trial (RCT) of digital breast tomosynthesis including synthesized two-dimensional mammograms (DBT) versus digital mammography (DM) in a population-based screening program for breast cancer and to compare selected secondary screening outcomes for the two techniques.

Methods

This RCT, performed in Bergen as part of BreastScreen Norway, was approved by the Regional Committees for Medical Health Research Ethics. All screening attendees in Bergen were invited to participate, of which 89% (14,274/15,976) concented during the first year, and were randomized to DBT (n = 7155) or DM (n = 7119). Secondary screening outcomes were stratified by mammographic density and compared using two-sample t-tests, chi-square tests, ANOVA, negative binomial regression and tests of proportions (z tests).

Results

Mean reading time was 1 min 11 s for DBT and 41 s for DM (p < 0.01). Mean time spent at consensus was 3 min 12 s for DBT and 2 min 12 s for DM (p < 0.01), while the rate of cases discussed at consensus was 6.4% and 7.4%, respectively for DBT and DM (p = 0.03). The recall rate was 3.0% for DBT and 3.6% for DM (p = 0.03). For women with non-dense breasts, recall rate was 2.2% for DBT versus 3.4% for DM (p = 0.04). The rate did not differ for women with dense breasts (3.6% for both). Mean glandular dose per examination was 2.96 mGy for DBT and 2.95 mGy for DM (p = 0.433).

Conclusions

Interim analysis of a screening RCT showed that DBT took longer to read than DM, but had significantly lower recall rate than DM. We found no differences in radiation dose between the two techniques.

Key Points

• In this RCT, DBT was associated with longer interpretation time than DM

• Recall rates were lower for DBT than for DM

• Mean glandular radiation dose did not differ between DBT and DM

A Simulation Screening Mammography Module Created for Instruction and Assessment: Radiology Residents vs National Benchmarks

RATIONALE AND OBJECTIVES

To improve mammographic screening training and breast cancer detection, radiology residents participated in a simulation screening mammography module in which they interpreted an enriched set of screening mammograms with known outcomes. This pilot research study evaluates the effectiveness of the simulation module while tracking the progress, efficiency, and accuracy of radiology resident interpretations and also compares their performance against national benchmarks.

MATERIALS AND METHODS

A simulation module was created with 266 digital screening mammograms enriched with high-risk breast lesions (seven cases) and breast malignancies (65 cases). Over a period of 27 months, 39 radiology residents participated in the simulation screening mammography module. Resident sensitivity and specificity were compared to Breast Cancer Surveillance Consortium (BCSC data through 2009) national benchmark and American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) acceptable screening mammography audit ranges.

RESULTS

The sensitivity, the percentage of cancers with an abnormal initial interpretation (BI-RADS 0), among residents was 84.5%, similar to the BCSC benchmark sensitivity of 84.9% (sensitivity for tissue diagnosis of cancer within 1 year following the initial examination) and within the acceptable ACR BI-RADS medical audit range of ≥75%. The specificity, the percentage of noncancers that had a negative image interpretation (BI-RADS 1 or 2), among residents was 83.2% compared to 90.3% reported in the BCSC benchmark data, but lower than the suggested ACR BI-RADS range of 88%-95%.

CONCLUSIONS

Using simulation modules for interpretation of screening mammograms is a promising method for training radiology residents to detect breast cancer and to help them achieve competence toward national benchmarks.