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Objective We aimed to investigate self-reported pain during screening with digital breast tomosynthesis (DBT). Methods The study was approved by the Regional Committee for Medical and Health Research Ethics in the South East of Norway (2015/424). Women completed a questionnaire about experienced pain directly after the examination, August–November 2019. A numeric rating scale (NRS, 0–10) was used. Data on compression force (N), pressure (kPa), and compressed breast thickness (mm) were obtained from the Digital Imaging and Communication in Medicine header and density assessment software. Stepwise ordinary least-squares regression was used to estimate mean self-reported pain score with 95% confidence interval (CI) for values of compression force, pressure, and compressed breast thickness. Results The mean pain score was 1.9, whereof 19.3% (822/4266) of the women reported moderate or severe pain. The mean pain score of 2.6 (95% CI: 2.4–2.7) was observed at a compression force of 60 N, decreasing to 1.3 (95% CI: 1.2–1.4) at 130 N. The mean pain score of 1.3 (95% CI: 1.1–1.4) was at a compression pressure of 6 kPa, increasing to 2.9 (95% CI: 2.7–3.1) at 16 kPa. The mean pain score was 0.6 (95% CI: 0.4–0.6) at a compressed breast thickness of 20 mm, increasing to 2.9 (95% CI: 2.7–3.1) at 90 mm. Conclusion The mean pain score was low, 1.9 on NRS, for women screened with DBT. A compression force of 60–130 N and a pressure 6–16 kPa were associated with no or mild pain.

Background Several studies in Europe and the US have shown promising results favouring digital breast tomosynthesis compared to standard digital mammography (DM). However, the costs of implementing the technology in screening programmes are not yet known. Methods A randomised controlled trial comparing the results from digital breast tomosynthesis including synthetic mammograms (DBT) vs. DM was performed in Bergen during 2016 and 2017 as a part of BreastScreen Norway. The trial included 29,453 women and allowed for a detailed comparison of procedure use and screening, recall and treatment costs estimated at the individual level. Results The increased cost of equipment, examination and reading time with DBT vs. DM was €8.5 per screened woman (95% CI 8.4−8.6). Costs of DBT remained significantly higher after adding recall assessment costs, €6.2 (95% CI 4.6−7.9). Substantial reductions in either examination and reading times, price of DBT equipment or price of IT storage and connectivity did not change the conclusion. Adding treatment costs resulted in too wide confidence intervals to draw definitive conclusions (additional costs of tomosynthesis €9.8, 95% CI –56 to 74). Performing biopsy at recall, radiation therapy and chemotherapy was significantly more frequent among women screened with DBT. Conclusion The results showed lower incremental costs of DBT vs. DM, compared to what is found in previous cost analyses of DBT and DM. However, the incremental costs were still higher for DBT compared with DM after including recall costs. Further studies with long-term treatment data are needed to understand the complete costs of implementing DBT in screening.

Background No evidence-based guidelines regarding optimal breast compression in mammography exist, neither for standard digital mammography nor for digital breast tomosynthesis. Purpose To compare breast compression parameters and mean glandular dose in a randomized controlled trial with digital mammography versus digital breast tomosynthesis. Material and Methods We used information from 21,729 women aged 50–69 years, who participated in the To-Be trial, as part of BreastScreen Norway, 2016–2017. Information was obtained from the DICOM header and by assessing the images in an automated software for density estimation (VolparaDensity). Using linear regression, we investigated the effect of screening technique on breast compression parameters; compression force (N), compression pressure (kPa), and compressed breast thickness (mm), and mean glandular dose (mGy), by view (craniocaudal [CC] and mediolateral oblique [MLO]). We adjusted for age, breast volume and fibroglandular volume. Results A total of 11,056 (50.9%) women were screened with digital mammography and 10,673 (49.1%) with digital breast tomosynthesis. Adjusted regression analysis showed that women undergoing digital mammography received higher compression forces than women undergoing digital breast tomosynthesis (CC: –4.7 N; MLO: –1.1 N, P Conclusion Women undergoing digital breast tomosynthesis received lower compression force, compression pressure, and compressed breast thickness in MLO view, compared to women undergoing digital mammography. Further studies should investigate the impact of breast compression on image quality, screening outcome, and radiation dose for digital mammography and digital breast tomosynthesis in order to establish evidence-based guidelines for breast compression.

Objectives To determine the agreement between artificial intelligence software (AI) and radiographers in assessing breast positioning criteria for mammograms from standard digital mammography and digital breast tomosynthesis. Methods Assessment of breast positioning was performed by AI and by four radiographers in pairs of two on 156 examinations of women screened in Bergen, April to September 2019, as part of BreastScreen Norway. Ten criteria were used; three for craniocaudal and seven for mediolateral-oblique view. The criteria evaluated the appearance of the nipple, breast rotation, pectoral muscle, inframammary fold and pectoral nipple line. Intraclass correlation and Cohen’s kappa coefficient (κ) were used to investigate the correlation and agreement between the radiographer’s assessments and AI. Results The intraclass correlation for the pectoral nipple line between the radiographers and AI was >0.92. A substantial to almost perfect agreement (κ > 0.69) was observed between the radiographers and AI on the nipple in profile criterion. We observed a slight to moderate agreement for the other criteria (κ = 0.06–0.52) and generally a higher agreement between the two pairs of radiographers (mean κ = 0.70) than between the radiographers and AI (mean κ = 0.41). Conclusions AI has great potential in evaluating breast position criteria in mammography by reducing subjectivity. However, varying agreement between radiographers and AI was observed. Standardized and evidence-based criteria for definitions, understandings and assessment methods are needed to reach optimal image quality in mammography.

Purpose: To compare the distribution of mammographic features among women recalled for further assessment after screening with digital breast tomosynthesis (DBT) versus digital mammography (DM), and to assess associations between features and final outcome of the screening, including immunohistochemical subtypes of the tumour. Methods: This randomized controlled trial was performed in Bergen, Norway, and included 28,749 women, of which 1015 were recalled due to mammographic findings. Mammographic features were classified according to a modified BI-RADS-scale. The distribution were compared using 95 % confidence intervals (CI). Results: Asymmetry was the most common feature of all recalls, 24.3 % (108/444) for DBT and 38.9 % (222/571) for DM. Spiculated mass was most common for breast cancer after screening with DBT (36.8 %, 35/95, 95 %CI: 27.2− 47.4) while calcifications (23.0 %, 20/87, 95 %CI: 14.6− 33.2) was the most frequent after DM. Among women screened with DBT, 0.13 % (95 %CI: 0.08− 0.21) had benign outcome after recall due to indistinct mass while the percentage was 0.28 % (95 %CI: 0.20− 0.38) for DM. The distributions were 0.70 % (95 %CI: 0.57− 0.85) versus 1.46 % (95 %CI: 1.27− 1.67) for asymmetry and 0.24 % (95 %CI: 0.16− 0.33) versus 0.54 % (95 %CI: 0.43− 0.68) for obscured mass, among women screened with DBT versus DM, respectively. Spiculated mass was the most common feature among women diagnosed with non-luminal A-like cancer after DBT and after DM. Conclusions: Spiculated mass was the dominant feature for breast cancer among women screened with DBT while calcifications was the most frequent feature for DM. Further studies exploring the clinical relevance of mammographic features visible particularly on DBT are warranted. This study was funded by the Research Council of Norway (the To-Be trial; project number 247941/H10), the Cancer Registry of Norway, and the Department of Radiology at Haukeland University Hospital.

Objective To investigate whether having the nipple imaged in profile was associated with breast characteristics or compression parameters, and whether it affected selected outcomes in screening with standard digital mammography or digital breast tomosynthesis. Methods In this IRB-approved retrospective study, results from 87 450 examinations (174 900 breasts) performed as part of BreastScreen Norway, 2016–2019, were compared by nipple in profile status and screening technique using descriptive statistics and generalized estimating equations. Unadjusted and adjusted odds ratios with 95% confidence intervals (95% CIs) were estimated for outcomes of interest, including age, breast volume, volumetric breast density, and compression force as covariates. Results Achieving the nipple in profile versus not in profile was associated with lower breast volume (845.1 cm3 versus 1059.9 cm3, P < 0.01) and higher mammographic density (5.6% versus 4.4%, P < 0.01). Lower compression force and higher compression pressure were applied to breasts with the nipple in profile (106.6 N and 11.5 kPa) compared to the nipple not in profile (110.8 N and 10.5 kPa, P < 0.01 for both). The adjusted odds ratio was 0.95 (95% CI: 0.88–1.02; P = 0.15) for recall and 0.92 (95% CI: 0.77–1.10; P = 0.36) for screen-detected cancer for nipple in profile versus not in profile. Conclusion Breast characteristics and compression parameters might hamper imaging of the nipple in profile. However, whether the nipple was in profile or not on the screening mammograms did not influence the odds of recall or screen-detected cancer, regardless of screening technique.

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. 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). 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). 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. • 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

Background Breast compression is used in mammography to improve image quality and reduce radiation dose. However, the compression may lead to discomfort or pain for the women. Breast compression time is longer with digital breast tomosynthesis (DBT) than with digital mammography (DM). We aimed to explore breast compression parameters with DM and DBT. Material and Methods We used information from 16,832 women participating in the Tomosynthesis Trial in Bergen between January 2016 and April 2017. We compared mean values of applied compression force (N), compression pressure (kPa) and compressed breast thickness (mm) for DM and DBT, by view (craniocaudal, CC, and mediolateral-oblique, MLO). Two-sample ttests were used to test statistical significance. Results Number of women screened with DM or DBT were similar (DM: n= 8354 and DBT: n= 8478). Mean compression force was statistically significantly higher for DM compared to DBT (CC: 108.6 N versus 102.7 N; MLO: 122.4 N versus 120.8 N, p Conclusion Radiographers applied less breast compression with DBT compared to DM. However, the observed differences were negligible. Further research should investigate the clinical implications of the differences, such as image quality.