Comparison of the Detection Rate of Simulated Microcalcifications in Full-Field Digital Mammography, Digital Breast Tomosynthesis, and Synthetically Reconstructed 2-Dimensional Images Performed With 2 Different Digital X-ray Mammography Systems

Audit of data from examination image headers collected for quality assurance in the ECOG-ACRIN EA1151 tomosynthesis mammographic imaging screening trial (TMIST)

PURPOSE

A comprehensive, centrally-monitored physics quality control (QC) program was developed for the Tomosynthesis Imaging Screening Trial (TMIST), a randomized controlled trial of digital breast tomosynthesis (TM) versus digital mammography (DM) for cancer screening. As part of the program, in addition to a set of phantom-based tests, de-identified data on image acquisition and processing parameters were captured from the DICOM headers of all individual patient images in the trial. These data were analyzed to assess the potential usefulness of header data from digital mammograms and tomosynthesis images of patients for quality assurance in breast imaging.

METHODS

Data were automatically extracted from the headers of all de-identified patient mammograms and tomosynthesis images in the TMIST study. Image acquisition parameters and estimated radiation doses were tracked for individual sites, systems and across system types. These parameters included (among others) kV, target/filter use, number of acquired views per examination, AEC mode, compression thickness and force and detector temperature. Consistency of manually entered study data parameters (subject ID, screening time-point) from TMIST was evaluated. Preliminary observations from the program are presented.

RESULTS

We report on data from 812 651 images from 135 525 examinations acquired between October, 2017 and December, 2022. Data came from 6 system models from 3 manufacturers. There was greater variability both in the number of views used and in the estimated (proxy) doses received in DM exams compared to TM. Mean proxy doses per examination varied among manufacturers from 2.76-4.54 mGy for DM and 3-4.84 mGy for the tomosynthesis component in the TM arm with maximum examination proxy doses of 20 and 26 mGy for DM and TM respectively. Mean proxy doses per examination for the combination examination in TM (tomosynthesis plus digital mammography) varied from 6.6 to 7.6 mGy among manufacturers with a maximum of 44.5 mGy.

CONCLUSIONS

Overall, modern digital mammography and tomosynthesis systems used in TMIST have operated very reliably. Doses vary considerably due to variation in the number of views per examination, thickness and fibro-glandularity of the breast, and choices in the use of synthesized versus actual 2D mammography in the TM examination. These data may also be useful in predicting equipment problems. Header information is valuable not only for automated QC, but also for cross-checking accuracy and consistency of data in a clinical study.

Stepwise Implementation of 2D Synthesized Screening Mammography and Its Effect on Stereotactic Biopsy of Microcalcifications

RATIONALE AND OBJECTIVES

Information evaluating the efficacy of 2D synthesized mammography (2Ds) reconstructions in microcalcification detection is limited. This study used stereotactic biopsy data for microcalcifications to evaluate the stepwise implementation of 2Ds in screening mammography. The study aim was to identify whether 2Ds + digital breast tomosynthesis (DBT) is non-inferior to 2D digital mammography (2DM) + 2Ds + DBT, 2DM + DBT, and 2DM in identifying microcalcifications undergoing further diagnostic imaging and stereotactic biopsy.

MATERIALS AND METHODS

Retrospective stereotactic biopsy data were extracted following 151,736 screening mammograms of healthy women (average age, 56.3 years; range, 30-89 years), performed between 2012 and 2019. The stereotactic biopsy data were separated into 2DM, 2DM + DBT, 2DM + 2Ds + DBT, and 2Ds + DBT arms and examined using Fisher's exact test to compare the detection rates of all cancers, invasive cancers, DCIS, and ADH between modalities for patients undergoing stereotactic biopsy of microcalcifications.

RESULTS

No statistical significance in cancer detection was seen for 2Ds + DBT among those calcifications that underwent stereotactic biopsy when comparing the 2Ds + DBT to 2DM, 2DM + DBT, and 2DM + 2Ds + DBT imaging combinations.

CONCLUSION

These data suggest that 2Ds + DBT is non-inferior to 2DM + DBT in detecting microcalcifications that will undergo stereotactic biopsy.

Prospective Comparison of Synthesized Mammography with DBT and Full-Field Digital Mammography with DBT Uncovers Recall Disagreements That may Impact Cancer Detection

RATIONALE AND OBJECTIVES

Synthesized mammography with digital breast tomosynthesis (SM+DBT) and full-field digital mammography with DBT were prospectively evaluated for recall rate (RR), cancer detection rate (CDR), positive predictive value 1 (PPV1), lesion recall differences, and disagreements in recall for additional imaging.

MATERIALS AND METHODS

From December 15, 2015 to January 15, 2017, after informed consent was obtained for this Health Insurance Portability and Accountability Act compliant study, each enrolled patient's SM+DBT and FFDM+DBT were interpreted sequentially by one of eight radiologists. RR, CDR, PPV1, and imaging findings (asymmetry, focal asymmetry, mass, architectural distortion, and calcifications) recalled were reviewed.

RESULTS

For SM+DBT and FFDM+DBT in 1022 patients, RR was 7.3% and 7.9% (SM+DBT vs. FFDM+DBT: diff= -0.6%; 90% CI= -1.4%, 0.1%); CDR was 6.8 and 7.8 per 1000 (SM+DBT vs. FFDM+DBT: diff= -1.0, 95% CI= -5.5, 2.8, p = 0.317); PPV1 was 9.3% and 9.9% (relative positive predictive value for SM+DBT vs. FFDM+DBT: 0.95, 95% CI: 0.73-1.22, p = 0.669). FFDM+DBT detected eight cancers; SM+DBT detected seven (missed 1 cancer with calcifications). SM+DBT and FFDM+DBT disagreed on patient recall for additional imaging in 19 patients, with majority (68%, 13/19 patients) in the recall of patients for calcifications. For calcifications, SM+DBT recalled six patients that FFDM+DBT did not recall, and FFDM+DBT recalled seven patients that SM+DBT did not recall, even though the total number of calcifications finding recalled was similar overall for both SM+DBT and FFDM+DBT.

CONCLUSION

Disagreement in recall of patients for calcifications may impact cancer detection by SM+DBT, warranting further investigation.

Performance of 2D Synthetic Mammography Versus Digital Mammography in the Detection of Microcalcifications at Screening

OBJECTIVE. The purpose of this study is to compare the performance of 2D synthetic mammography (SM) to that of full-field digital mammography (FFDM) in the detection of microcalcifications and to evaluate radiologists' preference between the two imaging modalities for assessing calcifications. MATERIALS AND METHODS. A fully crossed, mode-balanced, paired-case (n = 160), retrospective, multireader (n = 3) performance study was implemented to compare screening mammograms acquired with digital breast tomosynthesis and both FFDM and SM between 2015 and 2017. The study cohort included 70 patients with mammograms recalled for microcalcifications (35 with malignant findings and 35 with benign findings) and was supplemented with 90 patients with mammograms with negative findings. In separate sessions, readers interpreted SM or FFDM images by recording a BI-RADS assessment and the probability of malignancy. In a final session that included 70 mammograms with microcalcifications, readers recorded their subjective assessment of microcalcification conspicuity and diagnostic confidence. RESULTS. There was no difference in diagnostic accuracy as assessed by comparing the likelihood of malignancy based on the AUC of plotted ROCs, with AUCs of 91% (95% CI, 83-97%) and 88% (95% CI, 79-95%) observed for SM and FFDM, respectively (p = 0.392), and with noninferiority of SM compared with FFDM (p = 0.011). No significant difference was observed between SM and FFDM in terms of sensitivity (77% vs 73%, respectively; p = 0.366) or negative predictive value (84% vs 82%, respectively; p = 0.598). The specificity and positive predictive value of SM were lower than those of FFDM (91% vs 98%, respectively [p = 0.034], and 87% vs 96%, respectively [p = 0.034]). All readers found calcifications to be more conspicuous on SM (p < 0.0001); however, no significant difference in subjective diagnostic confidence was seen. CONCLUSION. SM is noninferior to FFDM in the detection of microcalcifications. Despite the increased conspicuity of microcalcifications on SM, the subjective diagnostic confidence in the two modalities is comparable.

Comparative analysis between synthetic mammography reconstructed from digital breast tomosynthesis and full-field digital mammography for breast cancer detection and visibility

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2D synthetic mammography images from the DBT dataset do not require additional radiation exposure.

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We compare observer performance between 2DSM and FFDM for breast cancer detection and visibility.

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Diagnostic performances of 2DSM and FFDM images were comparable for detecting breast cancers.

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2DSM may eliminate the need for additional FFDM during DBT-based imaging.

Purpose

To compare observer performance between synthetic mammography (2DSM) and full-field digital mammography (FFDM) for breast cancer detection and visibility.

Method

A retrospective analysis was conducted on 136 histopathologically proven cases of breast cancer in patients who underwent FFDM and digital breast tomosynthesis (DBT). 2DSM images were reconstructed from DBT data, and 2DSM and FFDM images were reviewed and evaluated for mammographic features, probability of malignancy (BI-RADS classification), and lesion conspicuity. DBT images were not reviewed. Statistical differences in cancer detection rates between 2DSM and FFDM images were analyzed using the McNemar test, agreement on BI-RADS assessment between 2DSM and FFDM was assessed using Cohen’s kappa test, and the Wilcoxon’s signed rank test was used to compare visibility scores.

Results

Mean cancer detection rates with 2DSM and FFDM images were 84.6 % and 87.8 %, respectively. In subgroup analyses, differences in breast density, tumor size, and presence of calcifications were not statistically significant. Agreement between 2DSM and FFDM images for BI-RADS classification was graded as good with Cohen’s k-coefficient of 0.78 ± 0.05. Visibility scores in both modalities of images were similar for all lesions combined; however, 2DSM had significantly better visibility scores for calcified cancers (p < 0.01), and in dense breast tissue (p < 0.01).

Conclusions

Diagnostic performances of 2DSM and FFDM images were comparable for detecting breast cancers, and it is possible that 2DSM may eliminate the need for additional FFDM during DBT-based imaging due to advances in image reconstruction methods.

Digital Variance Angiography as a Paradigm Shift in Carbon Dioxide Angiography

OBJECTIVES

Our aim was to investigate the feasibility of digital variance angiography (DVA) in lower extremity CO2 angiography and to compare the quantitative and qualitative performance of the new image processing technique with that of the current reference standard digital subtraction angiography (DSA).

MATERIALS AND METHODS

This prospective study enrolled 24 patients (mean age ± SD, 65.5 ± 9.2 years; 14 males, 65.1 ± 7.5 years; 10 females, 66.1 ± 11.6 years) undergoing lower-limb CO2 angiography between December 2017 and April 2018 at 2 clinical centers: The Heart and Vascular Center (HVC) of Semmelweis University, Budapest (7 patients), and the Bács-Kiskun County Hospital (BKCH) in Kecskemét (17 patients). The interventional protocol was similar at both sites, but the image acquisition instruments and protocols were different, which allowed us to investigate DVA in different settings. For comparison, the signal-to-noise ratio (SNR) of DSA and DVA images were calculated. The visual quality of DSA and DVA images were compared by independent clinical specialists using an online questionnaire. Interrater agreement was characterized by percent agreement and Fleiss kappa. The specialists also evaluated in a random and blinded manner the individual DSA and DVA images on a 5-grade scale ranging from poor (1) to outstanding (5) image quality, and the mean ± standard error of mean (SEM) was calculated.

RESULTS

A total of 4912 regions of interest were carefully selected in 110 image pairs to determine the SNRs. The ratio of SNRDVA/SNRDSA was calculated. At HVC, it ranged between 2.58 and 4.16 in the anatomical regions (abdominal, iliac, femoral, popliteal, crural, talar), and the overall median value was 3.53, whereas at BKCH the range was 2.71 to 4.92 and the overall median value was 4.52. During the visual evaluation, 120 DSA and DVA image pairs were compared. At HVC in 78%, although at BKCH in 90% of comparisons, it was judged that DVA provided higher quality images. The interrater agreement was 88% (P < 0.001) and 90% (P < 0.01), respectively. DVA images received consistently higher individual rating than DSA images, regardless of the research site and anatomical region. At HVC, the overall DSA and DVA scores (mean ± SEM) were 2.75 ± 0.12 and 3.23 ± 0.16, respectively (P < 0.05), whereas at BKCH these values were 2.49 ± 0.10 and 3.03 ± 0.09, respectively (P < 0.001).

CONCLUSIONS

These data show that lower-limb CO2 angiography DVA, regardless of the image acquisition instruments and protocols, produces higher SNR and significantly better image quality than DSA; therefore this new image processing technique might help the widespread use of CO2 as a safer contrast agent in clinical practice.

Synthetic 2-Dimensional Mammography Can Replace Digital Mammography as an Adjunct to Wide-Angle Digital Breast Tomosynthesis

OBJECTIVES

The aim of this study was to evaluate the detection rate and diagnostic performance of 2-dimensional synthetic mammography (SM) as an adjunct to wide-angle digital breast tomosynthesis (WA-DBT) compared with digital mammography (DM) alone or to DM in combination with WA-DBT.

MATERIALS AND METHODS

There were 205 women with 179 lesions included in this retrospective reader study. Patients underwent bilateral, 2-view (2v) DM and WA-DBT between March and June 2015. The standard of reference was histology and/or 1-year stability at follow-up. Four blinded readers randomly evaluated images according to the BI-RADS lexicon from 3 different protocols: 2v DM alone, 2v DM with 2v WA-DBT, and 2v SM with 2v WA-DBT. Detection rate, sensitivity, specificity, and accuracy were calculated and compared using multivariate analysis. Readers' confidence and image quality were evaluated.

RESULTS

The detection rate ranged from 68.7% to 79.9% for DM, 76.5% to 84.4% for DM with WA-DBT, and 73.2% to 84.9% for SM with WA-DBT. Sensitivity and accuracy were significantly higher when DBT was available (P < 0.001). Specificity did not differ significantly between DM only, DM with WA-DBT, or SM with WA-DBT (P ≥ 0.846). Wide-angle DBT combined readings did not differ between SM and DM in terms of sensitivity, specificity, and accuracy (P ≥ 0.341). Readers' confidence and image quality was rated good to excellent.

CONCLUSIONS

Wide-angle DBT combined with DM or SM increases sensitivity and accuracy without reducing specificity compared with DM alone. Wide-angle DBT combined readings did not differ between SM and DM; therefore, SM should replace DM for combined readings with WA-DBT.

A comparison of full-field digital mammograms versus 2D synthesized mammograms for detection of microcalcifications on screening

OBJECTIVES

To compare the observer agreement of microcalcification detection on synthetic 2D images to full field digital mammography (FFDM) at screening and determine if calcifications can be detected to the same degree and given the same BI-RADS assessment.

MATERIAL AND METHODS

Two-experienced radiologists retrospectively reviewed synthetic 2D images and FFDM, in separate sessions, to detect microcalcifications and provide a BIRADS assessment. A third experienced breast radiologist reviewed the cases that were disagreed upon and gave a final assessment. Between March 2016-December 2016, 414 women obtained a screening mammogram with tomosynthesis and acquisition of FFDM. 71 cases had combined FFDM and tomosynthesis images, calcifications visible on FFDM or no calcifications present, which comprised the study group. Synthetic 2D images were constructed from the DBT images. During session 1, all synthetic 2D images for the 71 cases were reviewed. During session 2, all the FFDM images for the 71 cases were reviewed. Tomosynthesis images were not reviewed. The agreement of detection of calcifications and BIRADS assessment between radiologists for FFDM and synthetic 2D images were assessed using Cohen's kappa test. Fisher's exact test was used to detect the differences in calcification identification among various breast densities on FFDM and synthetic 2D images.

RESULTS

For the detection of calcifications between synthetic 2D images and FFDM, there was moderate to substantial agreement (p-values < 0.0001) for the two radiologist. For the BIRADS assessments, the agreement between synthetic 2D imaging and FFDM was moderate (p-values < 0.0001). The inter-reader agreement for detection of calcifications was fair for using synthetic 2D and moderate for using FFDM (p-value < 0.0001). The final inter-reader agreement between FFDM and synthetic 2D images for the detection of calcifications was moderate (p-values < 0.0001) with the addition of the third reader. For the final BI-RADS assessment, there was moderate agreement between synthetic 2D imaging and FFDM (p-value < 0.0001). The two readers did not demonstrate a significant difference in the detection of microcalcifications for those who were dense or non-dense (p-value range 0.076-0.302).

CONCLUSION

Radiologist interpreting synthetic 2D imaging and FFDM have similar frequency for detection of calcifications and BIRADS assessment. A synthetic 2D mammogram may be a sufficient replacement for FFDM at screening.

Comparison of synthetic and digital mammography with digital breast tomosynthesis or alone for the detection and classification of microcalcifications

OBJECTIVE

To compare the performance of synthetic mammography (SM) and digital mammography (DM) with digital breast tomosynthesis (DBT) or alone for the evaluation of microcalcifications.

METHODS

This retrospective study includes 198 mammography cases, all with DM, SM, and DBT images, from January to October 2013. Three radiologists interpreted images and recorded the presence of microcalcifications and their conspicuity scores and final BI-RADS categories (1, 2, 3, 4a, 4b, 4c, 5). Readers' area under the ROC curves (AUCs) were analyzed for SM plus DBT vs. DM plus DBT and SM alone vs. DM alone using the BI-RADS categories for the overall group and dense breast subgroup.

RESULTS

Conspicuity scores of detected microcalcifications were neither significantly different between SM and DM with DBT nor alone (p>0.05). In predicting malignancy of detected microcalcifications, no significant difference was found between readers' AUCs for SM and DM with DBT or alone in the overall group or dense breast subgroup (p>0.05).

CONCLUSIONS

Diagnostic performances of SM and DM for the evaluation of microcalcifications are not significantly different, whether performed with DBT or alone.

KEY POINTS

• In DBT-imaging, SM and DM show comparable performances when evaluating microcalcifications. • For BI-RADS classification of microcalcifications, SM and DM show similar AUCs. • DBT with SM may be sufficient for diagnosing microcalcifications, without DM.

Breast density: why all the fuss?

The term "breast density" or mammographic density (MD) denotes those components of breast parenchyma visualised at mammography that are denser than adipose tissue. MD is composed of a mixture of epithelial and stromal components, notably collagen, in variable proportions. MD is most commonly assessed in clinical practice with the time-honoured method of visual estimation of area-based percent density (PMD) on a mammogram, with categorisation into quartiles. The computerised semi-automated thresholding method, Cumulus, also yielding area-based percent density, is widely used for research purposes; however, the advent of fully automated volumetric methods developed as a consequence of the widespread use of digital mammography (DM) and yielding both absolute and percent dense volumes, has resulted in an explosion of interest in MD recently. Broadly, the importance of MD is twofold: firstly, the presence of marked MD significantly reduces mammographic sensitivity for breast cancer, even with state-of-the-art DM. Recognition of this led to the formation of a powerful lobby group ('Are You Dense') in the US, as a consequence of which 32 states have legislated for mandatory disclosure of MD to women undergoing mammography. Secondly, it is now widely accepted that MD is in itself a risk factor for breast cancer, with a four-to sixfold increased relative risk in women with PMD in the highest quintile compared to those with PMD in the lowest quintile. Consequently, major research efforts are underway to assess whether use of MD could provide a major step forward towards risk-adapted, personalised breast cancer prevention, imaging, and treatment.

Comparison of synthetic mammography, reconstructed from digital breast tomosynthesis, and digital mammography: evaluation of lesion conspicuity and BI-RADS assessment categories

PURPOSE

To compare the interpretive performance of synthetic mammography (SM), reconstructed from digital breast tomosynthesis (DBT), and full-field digital mammography (FFDM) in a diagnostic setting, covering different conditions of breast density and mammographic signs.

METHODS

A retrospective analysis was conducted on 231 patients, who underwent FFDM and DBT (from which SM images were reconstructed) between September 2014-September 2015. The study included 250 suspicious breast lesions, all biopsy proven: 148 (59.2%) malignant and 13 (5.2%) high-risk lesions were confirmed by surgery, 89 (35.6%) benign lesions had radiological follow-up. Two breast radiologists, blinded to histology, independently reviewed all cases. Readings were performed with SM alone, then with FFDM, collecting data on: probability of malignancy for each finding, lesion conspicuity, mammographic features and dimensions of detected lesions.

RESULTS

Agreement between readers was good for BI-RADS classification (Cohen's k-coefficient = 0.93 ± 0.02) and for lesion dimension (Wilcoxon's p = 0.76). Visibility scores assigned to SM and FFDM for each lesion were similar for non-dense and dense breasts, however, there were significant differences (p = 0.0009) in distribution of mammographic features subgroups. SM and FFDM had similar sensitivities in non-dense (respectively 94 vs. 91%) and dense breasts (88 vs. 80%) and for all mammographic signs (93 vs. 87% for asymmetric densities, 96 vs. 75% for distortion, 92 vs. 85% for microcalcifications, and both 94% for masses). Based on all data, there was a significant difference in sensitivity for SM (92%) vs. FFDM (87%), p = 0.02, whereas the two modalities yielded similar results for specificity (SM: 60%, FFDM: 62%, p = 0.21).

CONCLUSIONS

SM alone showed similar interpretive performance to FFDM, confirming its potential role as an alternative to FFDM in women having tomosynthesis, with the added advantage of halving the patient's dose exposure.

Visualization of Breast Microcalcifications on Digital Breast Tomosynthesis and 2-Dimensional Digital Mammography Using Specimens

Purpose:

The purpose of this study is to compare the visibility of microcalcifications of digital breast tomosynthesis (DBT) and full-field digital mammography (FFDM) using breast specimens.

Materials And Methods:

Thirty-one specimens’ DBT and FFDM were retrospectively reviewed by four readers.

Results:

The image quality of microcalcifications of DBT was rated as superior or equivalent in 71.0% by reader 1, 67.8% by reader 2, 64.5% by reader 3, and 80.6% by reader 4. The Fleiss kappa statistic for agreement among readers was 0.31.

Conclusions:

We suggest that image quality of DBT appears to be comparable with or better than FFDM in terms of revealing microcalcifications.