The Postoperative Breast: Imaging Findings and Diagnostic Pitfalls After Breast-Conserving Surgery and Oncoplastic Breast Surgery

Breast surgery is the cornerstone of treatment for early breast cancer. Historically, mastectomy and conventional breast-conserving surgery (BCS) were the main surgical techniques for treatment. Now, oncoplastic breast surgery (OBS), introduced in the 1990s, allows for a combination of BCS and reconstructive surgery to excise the cancer while preserving or enhancing the contour of the breast, leading to improved aesthetic results. Although imaging after conventional lumpectomy demonstrates typical postsurgical changes with known evolution patterns over time, OBS procedures show postsurgical changes/fat necrosis in locations other than the lumpectomy site. The purpose of this article is to familiarize radiologists with various types of surgical techniques for removal of breast cancer and to distinguish benign postoperative imaging findings from suspicious findings that warrant further work-up.

Sustaining Mammography Image Quality With a Technologist Coaching Program in the Era of the Enhancing Quality Using the Inspection Program (EQUIP)

OBJECTIVE

To evaluate the ability of a long-term technologist coaching program to sustain gains in mammography quality made by a previously implemented quality improvement (QI) initiative.

METHODS

Mammography quality metrics from July 2014 to June 2020 were reviewed. Numbers of screening mammograms performed/audited, monthly average mammogram overall quality pass rates, changes in facilities/staffing, and technical recall rates were evaluated. Performance metrics at baseline (July 2013), during the improvement (July 2014 to January 2015), postimprovement (February 2015 to August 2015), and sustained coaching periods (after initiation of the technologist coaching model, from September 2015 to June 2020) were compared.

RESULTS

During the postimprovement and sustained coaching periods, 93% (501/541) and 90% (8902/9929) of audited mammograms, respectively, met overall passing criteria, achieving or exceeding the QI goal of 90%, and results for both periods were significantly higher than that during the improvement period (74%, 1098/1489), at P < 0.0001 and P < 0.0001, respectively. The technical recall rates during the improvement and postimprovement periods were 2.6% (85/3321) and 1.7% (54/3236), respectively; the rate during the sustained coaching period was significantly lower than these, at 1.2% (489/40 440) (P < 0.0001 and P = 0.0232, respectively). Sustained quality passing rates and lower technical recall rates were observed despite statistically significantly increases in screening volumes.

CONCLUSION

A technologist coaching program resulted in sustained high mammographic quality for almost 5 years.

Breast Density Legislation Impact on Breast Cancer Screening and Risk Assessment

OBJECTIVE

To evaluate breast density notification legislation (BDNL) on breast imaging practice patterns, risk assessment, and supplemental screening.

METHODS

A 20-question anonymous web-based survey was administered to practicing Society of Breast Imaging radiologists in the U.S. between February and April 2021 regarding breast cancer risk assessment, supplemental screening, and density measurements. Results were compared between facilities with and without BDNL using the two-sided Fisher's exact test.

RESULTS

One hundred and ninety-seven radiologists from 41 U.S. states, with (187/197, 95%) or without (10/197, 5%) BDNL, responded. Fifty-seven percent (113/197) performed breast cancer risk assessment, and 93% (183/197) offered supplemental screening for women with dense breasts. Between facilities with or without BDNL, there was no significant difference in whether risk assessment was (P = 0.19) or was not performed (P = 0.20). There was no significant difference in supplemental screening types (P > 0.05) between BDNL and non-BDNL facilities. Thirty-five percent (69/197) of facilities offered no supplemental screening studies, and 25% (49/197) had no future plans to offer supplemental screening. A statistically significant greater proportion of non-BDNL facilities offered no supplemental screening (P < 0.03) and had no plans to offer supplemental screening compared to BDNL facilities (P < 0.02).

CONCLUSION

Facilities in BDNL states often offer supplemental screening compared to facilities in non-BDNL states. Compared to BDNL facilities, a statistically significant proportion of non-BDNL facilities had no supplemental screening nor plans for implementation. Our data suggest that upcoming federal BDNL will impact how supplemental screening is addressed in currently non-BDNL states.

Frequency and Outcomes of Ipsilateral Axillary Lymphadenopathy After COVID-19 Vaccination

This case series reports on the frequency and outcomes of breast imaging–identified ipsilateral axillary lymphadenopathy after recent COVID-19 vaccination among women.

Harnessing artificial intelligence to automate delineation of volumetric breast cancers from magnetic resonance imaging to improve tumor characterization

597

Background: Automated breast tumor identification and segmentation in magnetic resonance imaging (MRI) is a difficult and crucial area of study in breast cancer research. Artificial intelligence (AI) models are increasingly being developed for automated localization of lesions in imaging studies to facilitate quantitative assessment of features for improved diagnostic, prognostic and predictive performance. Such models have had success in detecting breast cancers in mammography, ultrasound and CT, but few have achieved three-dimensional (3D) volumetric tumor segmentation from breast MRI. The purpose of this study was to apply two state-of-the-art AI – specifically, deep learning (DL) - algorithms to 3D MRI breast cancer data and identify the higher performing algorithm for precise segmentation of breast tumors. Methods: We evaluated pre-treatment, T1 post-gadolinium contrast enhanced breast MRI from 222 patients with known breast cancers (n = 262). Images were split into training (n = 142), validation (n = 36), and hold-out test (n = 44) datasets. Two DL algorithms, U-Net and VAE-UNet, were trained to classify tumors on the training dataset across 1000 epochs. The output for each is a precise localization and segmentation of each tumor at the pixel level from every MRI image. We evaluated the performance of each algorithm using 5-fold cross-validation and testing on the validation and test sets. We calculated a dice accuracy score for each model as the performance comparison metric. Results: The highest dice accuracy score achieved on the validation dataset by generic U-Net was 83.38%, with an average across 1000 epochs of 62.41%. The highest dice accuracy achieved on the validation dataset by VAE-UNet was 82.62%, with an average across epochs of 61.28%. On our test dataset, the highest dice accuracy score achieved by U-Net was 93.09%, with an average across epochs of 66.31%, and the highest accuracy score for VAE-UNet was 90.98%, with average across epochs of 50.47%. Although U-Net appeared to perform slightly better than VAE-Unet for most cases, there were distinct cases where VAE-UNet outperformed U-Net (dice score up to 59% better than U-Net). Subsequent analysis indicated that VAE-UNet preferentially outperforms U-Net for tumors with low sphericity (p = 0.001). Conclusions: Our results suggest that U-Net is well suited for segmenting breast tumors from breast MRI in most cases, but that VAE-UNet outperforms U-Net when the tumor shapes are less spherical. Our findings could inform the choice of DL algorithms in research and clinical endeavors that rely on accurate breast cancer tumor segmentation. In particular, these two tools could be configured to facilitate tumor assessment from breast MRI in the clinical setting for: breast cancer screening in high-risk patient populations, pre-surgical planning, and monitoring of treatment response.

Radiomic features quantifying pixel-level characteristics of breast tumors from magnetic resonance imaging predict risk factors in triple-negative breast cancer

e12612

Background: Computationally derived quantitative imaging (radiomic) features that describe tumor phenotypes at the pixel level have demonstrated associations with clinical characteristics in early investigations of other cancers. This implies that molecular differences among tumors may be reflected in their structure on the scales probed by 3D magnetic resonance imaging (MRI). We investigated whether radiomic features computed over tumor volumes from pre-treatment breast MRI could predict risk factors in triple-negative breast cancer (TNBC). Methods: We evaluated breast tumors on pre-treatment, post-contrast T1-weighted MRI from 156 patients with non-metastatic TNBC who underwent neoadjuvant chemotherapy. Tumor regions of interest were segmented by a convolutional neural network algorithm, with validation by breast radiologists. Features quantifying tumor shape and texture were extracted for the largest tumor present in each patient. We identified 23 principal components (PCs) describing these data within the original 364-dimensional feature space for further analysis. Tumor volume was also extracted for comparison with the shape and texture PCs, clinical variables and outcomes, but was kept separate from other radiomic features, since it directly correlates with clinical stage. We compiled for the cohort clinical variables including demographics, stage, grade, and, where available, absolute lymphocyte count (ALC) and Ki-67, a cellular proliferation index routinely used in clinical practice. We then performed a series of univariate and multivariate regression analyses to identify radiomic PCs and clinical variables that significantly predict patient outcomes, and radiomic PCs that predict established risk factors. Our multivariate analyses utilized 5-fold cross-validation and Monte-Carlo determination of p-values (based on 3000 random samplings from the null hypothesis), to ensure statistical rigor in identifying predictive relationships while correcting for multiple hypothesis testing. Results: Our univariate analyses confirmed expected correlations between: overall survival and pre-treatment tumor volume (p = 0.010); survival and ALC (p = 0.002); and clinical stage and tumor volume (p = 1.2⨉10-7). From our multivariate analysis, shape and texture radiomic features were predictive of: tumor volume (p < 0.001); clinical stage (p < 0.001); and Ki-67 (p = 0.02). We confirmed that Ki-67 was predictive of post-treatment residual cancer (p = 0.014), as has been previously reported. Conclusions: Radiomic features predict breast cancer risk factors that are significant for determining outcomes for TNBC patients. Combinations of radiomic shape and texture features track closely with tumor volumes, stage, and proliferative activity, potentially reflecting underlying molecular evolution.

Use of breast MRI to distinguish treatment failure versus new primary tumor following single fraction breast intraoperative radiotherapy for breast cancer (SF-IORT)

e12534

Background: Single-fraction, intraoperative radiation therapy (SF-IORT) can replace whole breast radiotherapy (WBT) in select patients after lumpectomy for breast cancer. By combining histology review with co-registration of breast MRI at diagnosis and following an in-breast tumor recurrence, we sought to characterize IBTR as: missed on initial MRI, treatment failure, or new primary tumor. This has important implications for both breast MRI and understanding the effectiveness of SF-IORT. Methods: We reviewed our IORT database for patients with IBTR. Three radiologists recorded findings on DCE-MRI, mammograms and ultrasound, pathology at initial diagnosis and IBTR, and time to IBTR. Results: 90 women received SF-IORT between 12/6/2002 - 4/10/2019. There were 6 IBTRs (average age at recurrence 63, range 49-71 years). For these 6 patients, initial diagnostic mammograms showed fatty (1), scattered (4) or extremely dense (1) breasts with suspicious masses (4), calcifications (1), or asymmetry (1), average size 1.4 cm: range 0.3 - 2.0 cm. On MRI, background parenchymal enhancement was minimal (2), mild (2), moderate (1), or marked (1), showing a mass (4), mass/distortion (1), or post-biopsy marker/no abnormal enhancement (1). Initial pathology showed 2 IDC, 3 IDC/DCIS, and 1 DCIS, (average size 1.7 cm, range 1.1 - 2.4 cm) with 6/6 ER +, 5/6 PR + and 6 HER2 negative. IDC Ki-67 ranged from 5-25%. 5/6 patients had sentinel lymph node biopsy (SLNB) with 1/5 having a positive SLN. 4/6 received endocrine therapy. One patient declined follow-up mammography. After IORT, IBTR (average size 1.4 cm, range 0.7 - 3.6 cm) was diagnosed by mammography (3), palpable breast lump (2), or palpable axillary lymph node (LN) (1) shown as mass (4), mass/calcifications (1), or abnormal LN (1). IBTR occurred post-SF-IORT an average of 141.7 months, range 88.3 to 195.8 months. 2/6 IBTR occurred near the biopsy cavity. Subsequent surgery included mastectomy (3), re-excision lumpectomy/RT (2), or axillary LN dissection/RT (1) showing 4 IDC, 1 IDC/DCIS, and 1 IDC /ILC (6/6 ER +; 3/6 PR positive; 2 PR weakly positive; and 5 HER2 negative, 1 HER2 equivocal). Ki-67 ranged from 1-70%. Conclusions: 6/90 (6.6%) patients had an IBTR an average of 141.7 months post SF-IORT with 2/6 near the biopsy cavity. Breast MRI reliably screens patients for SF-IORT. Co-registration of imaging can help distinguish true recurrences from new primary tumors.

A Proposed Dedicated Breast PET Lexicon: Standardization of Description and Reporting of Radiotracer Uptake in the Breast

Dedicated breast positron emission tomography (dbPET) is a new diagnostic imaging modality recently used in clinical practice for the detection of breast cancer and the assessment of tumor biology. dbPET has higher spatial resolution than that of conventional whole body PET systems, allowing recognition of detailed morphological attributes of radiotracer accumulation within the breast. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) accumulation in the breast may be due to benign or malignant entities, and recent studies suggest that morphology characterization of ¹⁸F-FDG uptake could aid in estimating the probability of malignancy. However, across the world, there are many descriptors of breast ¹⁸F-FDG uptake, limiting comparisons between studies. In this article, we propose a lexicon for breast radiotracer uptake to standardize description and reporting of image findings on dbPET, consisting of terms for image quality, radiotracer fibroglandular uptake, breast lesion uptake.

How does image quality affect radiologists' perceived ability for image interpretation and lesion detection in digital mammography?

OBJECTIVES

To study how radiologists' perceived ability to interpret digital mammography (DM) images is affected by decreases in image quality.

METHODS

One view from 45 DM cases (including 30 cancers) was degraded to six levels each of two acquisition-related issues (lower spatial resolution and increased quantum noise) and three post-processing-related issues (lower and higher contrast and increased correlated noise) seen during clinical evaluation of DM systems. The images were shown to fifteen breast screening radiologists from five countries. Aware of lesion location, the radiologists selected the most-degraded mammogram (indexed from 1 (reference) to 7 (most degraded)) they still felt was acceptable for interpretation. The median selected index, per degradation type, was calculated separately for calcification and soft tissue (including normal) cases. Using the two-sided, non-parametric Mann-Whitney test, the median indices for each case and degradation type were compared.

RESULTS

Radiologists were not tolerant to increases (medians: 1.5 (calcifications) and 2 (soft tissue)) or decreases (median: 2, for both types) in contrast, but were more tolerant to correlated noise (median: 3, for both types). Increases in quantum noise were tolerated more for calcifications than for soft tissue cases (medians: 3 vs. 4, p = 0.02). Spatial resolution losses were considered less acceptable for calcification detection than for soft tissue cases (medians: 3.5 vs. 5, p = 0.001).

CONCLUSIONS

Perceived ability of radiologists for image interpretation in DM was affected not only by image acquisition-related issues but also by image post-processing issues, and some of those issues affected calcification cases more than soft tissue cases.

KEY POINTS

• Lower spatial resolution and increased quantum noise affected the radiologists' perceived ability to interpret calcification cases more than soft tissue lesion or normal cases. • Post-acquisition image processing-related effects, not only image acquisition-related effects, also impact the perceived ability of radiologists to interpret images and detect lesions. • In addition to current practices, post-acquisition image processing-related effects need to also be considered during the testing and evaluation of digital mammography systems.

Validation of a candidate instrument to assess image quality in digital mammography using ROC analysis

PURPOSE

To validate a candidate instrument, to be used by different professionals to assess image quality in digital mammography (DM), against detection performance results.

METHODS

A receiver operating characteristics (ROC) study was conducted to assess the detection performance in DM images with four different image quality levels due to different quality issues. Fourteen expert breast radiologists from five countries assessed a set of 80 DM cases, containing 60 lesions (40 cancers, 20 benign findings) and 20 normal cases. A visual grading analysis (VGA) study using a previously-described candidate instrument was conducted to evaluate a subset of 25 of the images used in the ROC study. Eight radiologists that had participated in the ROC study, and seven expert breast-imaging physicists, evaluated this subset. The VGA score (VGAS) and the ROC and visual grading characteristics (VGC) areas under the curve (AUCROC and AUCVGC) were compared.

RESULTS

No large differences in image quality among the four levels were detected by either ROC or VGA studies. However, the ranking of the four levels was consistent: level 1 (partial AUCROC: 0.070, VGAS: 6.77) performed better than levels 2 (0.066, 6.15), 3 (0.061, 5.82), and 4 (0.062, 5.37). Similarity between radiologists' and physicists' assessments was found (average VGAS difference of 10 %).

CONCLUSIONS

The results from the candidate instrument were found to correlate with those from ROC analysis, when used by either observer group. Therefore, it may be used by different professionals, such as radiologists, radiographers, and physicists, to assess clinically-relevant image quality variations in DM.

Adaptations of Breast Imaging Centers to the COVID-19 Pandemic: A Survey of California and Texas

OBJECTIVE

To determine the early impact of the COVID-19 pandemic on breast imaging centers in California and Texas and compare regional differences.

METHODS

An 11-item survey was emailed to American College of Radiology accredited breast imaging facilities in California and Texas in August 2020. A question subset addressed March-April government restrictions on elective services ("during the shutdown" and "after reopening"). Comparisons were made between states with chi-square and Fisher's tests, and timeframes with McNemar's and paired t-tests.

RESULTS

There were 54 respondents (54/240, 23%, 26 California, 28 Texas). Imaging volumes fell during the shutdown and remained below pre-pandemic levels after reopening, with reduction in screening greatest (ultrasound 12% of baseline, mammography 13%, MRI 23%), followed by diagnostic MRI (43%), procedures (44%), and diagnostics (45%). California reported higher volumes during the shutdown (procedures, MRI) and after reopening (diagnostics, procedures, MRI) versus Texas (P = 0.001-0.02). Most screened patients (52/54, 96% symptoms and 42/54, 78% temperatures), and 100% (53/53) modified check-in and check-out. Reading rooms or physician work were altered for social distancing (31/54, 57%). Physician mask (45/48, 94%), gown (15/48, 31%), eyewear (22/48, 46%), and face shield (22/48, 46%) use during procedures increased after reopening versus pre-pandemic (P < 0.001-0.03). Physician (47/54, 87%) and staff (45/53, 85%) financial impacts were common, but none reported terminations.

CONCLUSION

Breast imaging volumes during the early pandemic fell more severely in Texas than in California. Safety measures and financial impacts on physicians and staff were similar in both states.

Interval Breast Cancer Rates and Tumor Characteristics in the Prospective Population-based Malmö Breast Tomosynthesis Screening Trial

Background Interval cancer rates can be used to evaluate whether screening with digital breast tomosynthesis (DBT) contributes to a screening benefit. Purpose To compare interval cancer rates and tumor characteristics in DBT screening to those in a contemporary population screened with digital mammography (DM). Materials and Methods The prospective population-based Malmö Breast Tomosynthesis Screening Trial (MBTST) was designed to compare one-view DBT to two-view DM in breast cancer detection. The interval cancer rates and cancer characteristics in the MBTST were compared with an age-matched contemporary control group, screened with two-view DM at the same center. Conditional logistic regression was used for data analysis. Results There were 14 848 women who were screened with DBT and DM in the MBTST between January 2010 and February 2015. The trial women were matched with two women of the same age and screening occasion at DM screening during the same period. Matches for 13 369 trial women (mean age, 56 years ± 10 [standard deviation]) were found with 26 738 women in the control group (mean age, 56 years ± 10). The interval cancer rate in the MBTST was 1.6 per 1000 screened women (21 of 13 369; 95% CI: 1.0, 2.4) compared with 2.8 per 1000 screened women in the control group (76 of 26 738 [95% CI: 2.2, 3.6]; conditional odds ratio, 0.6 [95% CI: 0.3, 0.9]; P = .02). The invasive interval cancers in the MBTST and in the control group showed in general high Ki-67 (63% [12 of 19] and 75% [54 of 72]), and low proportions of luminal A-like subtype (26% [five of 19] and 17% [12 of 72]), respectively. Conclusion The reduced interval cancer rate after screening with digital breast tomosynthesis compared with a contemporary age-matched control group screened with digital mammography might translate into screening benefits. Interval cancers in the trial generally had nonfavorable characteristics. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Mann in this issue.

Impact of the COVID-19 Pandemic on Breast Imaging Education

Objective

To determine the impact of the COVID-19 pandemic on breast imaging education.

Methods

A 22-item survey addressing four themes during the early pandemic (time on service, structured education, clinical training, future plans) was emailed to Society of Breast Imaging members and members-in-training in July 2020. Responses were compared using McNemar's and Mann-Whitney U tests; a general linear model was used for multivariate analysis.

Results

Of 136 responses (136/2824, 4.8%), 96 U.S. responses from radiologists with trainees, residents, and fellows were included. Clinical exposure declined during the early pandemic, with almost no medical students on service (66/67, 99%) and fewer clinical days for residents (78/89, 88%) and fellows (48/68, 71%). Conferences shifted to remote live format (57/78, 73%), with some canceled (15/78, 19%). Compared to pre-pandemic, resident diagnostic (75/78, 96% vs 26/78, 33%) (P < 0.001) and procedural (73/78, 94% vs 21/78, 27%) (P < 0.001) participation fell, as did fellow diagnostic (60/61, 98% vs 47/61, 77%) (P = 0.001) and procedural (60/61, 98% vs 43/61, 70%) (P < 0.001) participation. Most thought that the pandemic negatively influenced resident and fellow screening (64/77, 83% and 43/60, 72%, respectively), diagnostic (66/77, 86% and 37/60, 62%), and procedural (71/77, 92% and 37/61, 61%) education. However, a majority thought that decreased time on service (36/67, 54%) and patient contact (46/79, 58%) would not change residents' pursuit of a breast imaging fellowship.

Conclusion

The pandemic has had a largely negative impact on breast imaging education, with reduction in exposure to all aspects of breast imaging. However, this may not affect career decisions.

Multishot Diffusion-Weighted MRI of the Breast With Multiplexed Sensitivity Encoding (MUSE) and Shot Locally Low-Rank (Shot-LLR) Reconstructions

BACKGROUND

Diffusion-weighted imaging (DWI) has shown promise to screen for breast cancer without a contrast injection, but image distortion and low spatial resolution limit standard single-shot DWI. Multishot DWI methods address these limitations but introduce shot-to-shot phase variations requiring correction during reconstruction.

PURPOSE

To investigate the performance of two multishot DWI reconstruction methods, multiplexed sensitivity encoding (MUSE) and shot locally low-rank (shot-LLR), compared to single-shot DWI in the breast.

STUDY TYPE

Prospective.

POPULATION

A total of 45 women who consented to have multishot DWI added to a clinically indicated breast MRI.

FIELD STRENGTH/SEQUENCES

Single-shot DWI reconstructed by parallel imaging, multishot DWI with four or eight shots reconstructed by MUSE and shot-LLR, 3D T2 -weighted imaging, and contrast-enhanced MRI at 3T.

ASSESSMENT

Three blinded observers scored images for 1) general image quality (perceived signal-to-noise ratio [SNR], ghosting, distortion), 2) lesion features (discernment and morphology), and 3) perceived resolution. Apparent diffusion coefficient (ADC) of the lesion was also measured and compared between methods.

STATISTICAL TESTS

Image quality features and perceived resolution were assessed with a mixed-effects logistic regression. Agreement among observers was estimated with a Krippendorf's alpha using linear weighting. Lesion feature ratings were visualized using histograms, and correlation coefficients of lesion ADC between different methods were calculated.

RESULTS

MUSE and shot-LLR images were rated to have significantly better perceived resolution (P < 0.001), higher SNR (P < 0.005), and a lower level of distortion (P < 0.05) with respect to single-shot DWI. Shot-LLR showed reduced ghosting artifacts with respect to both MUSE (P < 0.001) and single-shot DWI (P < 0.001). Eight-shot DWI had improved perceived SNR and perceived resolution with respect to four-shot DWI (P < 0.005).

DATA CONCLUSION

Multishot DWI enables increased resolution and improved image quality with respect to single-shot DWI in the breast. Shot-LLR reconstructs multishot DWI with minimal ghosting artifacts. The improvement of multishot DWI in image quality increases with an increased number of shots.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 2.

Development and content validity evaluation of a candidate instrument to assess image quality in digital mammography: A mixed-method study

PURPOSE

To develop a candidate instrument to assess image quality in digital mammography, by identifying clinically relevant features in images that are affected by lower image quality.

METHODS

Interviews with fifteen expert breast radiologists from five countries were conducted and analysed by using adapted directed content analysis. During these interviews, 45 mammographic cases, containing 44 lesions (30 cancers, 14 benign findings), and 5 normal cases, were shown with varying image quality. The interviews were performed to identify the structures from breast tissue and lesions relevant for image interpretation, and to investigate how image quality affected the visibility of those structures. The interview findings were used to develop tentative items, which were evaluated in terms of wording, understandability, and ambiguity with expert breast radiologists. The relevance of the tentative items was evaluated using the content validity index (CVI) and modified kappa index (k*).

RESULTS

Twelve content areas, representing the content of image quality in digital mammography, emerged from the interviews and were converted into 29 tentative items. Fourteen of these items demonstrated excellent CVI ≥ 0.78 (k* > 0.74), one showed good CVI < 0.78 (0.60 ≤ k* ≤ 0.74), while fourteen were of fair or poor CVI < 0.78 (k* ≤ 0.59). In total, nine items were deleted and five were revised or combined resulting in 18 items.

CONCLUSIONS

By following a mixed-method methodology, a candidate instrument was developed that may be used to characterise the clinically-relevant impact that image quality variations can have on digital mammography.

Clumped vs non-clumped internal enhancement patterns in linear non-mass enhancement on breast MRI

OBJECTIVE

To compare positive predictive values (PPVs) of clumped vs non-clumped (homogenous and heterogeneous) internal enhancement on MRI detected linear non-mass enhancement (NME) on MRI-guided vacuum-assisted breast biopsy (MRI-VABB).

METHODS

With IRB (Institutional Review Board) approval, we retrospectively reviewed 598 lesions undergoing MRI-VABB from January 2015 to April 2018 that showed linear NME. We reviewed the electronic medical records for MRI-VABB pathology, any subsequent surgery and clinical follow-up. The X² test was performed for univariate analysis.

RESULTS

There were 120/598 (20%) linear NME MRI-VABB lesions with clumped (52/120, 43%) vs non-clumped (68/120, 57%) internal enhancement, average size 1.8 cm (range 0.6-7.6 cm). On MRI-VABB, cancer was identified in 22/120 (18%) lesions, ductal carcinoma in situ (DCIS) was found in 18/22 (82%) and invasive cancer in 4 (18%). 3/31 (10%) high-risk lesions upgraded to DCIS at surgery, for a total of 25/120 (21%) malignancies. Malignancy was found in 12/52 (23%) clumped lesions and in 13/68 (19%) of non-clumped lesions that showed heterogeneous (5/13, 38%) or homogenous (8/13, 62%) internal enhancement. The PPV of linear NME with clumped internal enhancement (23.1%) was not significantly different from the PPV of non-clumped linear NME (19.1%) (p = 0.597). The PPV of linear NME lesions <1 cm (33.3%) was not significantly different from the PPV of lesions ≥1 cm (18.6%) (p = 0.157).

CONCLUSIONS

Linear NME showed malignancy in 21% of our series. Linear NME with clumped or non-clumped internal enhancement patterns, regardless of lesion size, might need to undergo MRI-VABB in appropriate populations.

ADVANCES IN KNOWLEDGE

Evaluation of linear NME lesions on breast MRI focuses especially on internal enhancement pattern.

Pure Fibrocystic Change Diagnosed at MRI-guided Vacuum-assisted Breast Biopsy: Imaging Features and Follow-up Outcomes

OBJECTIVE

Fibrocystic change (FCC) is considered one of the most common benign findings in the breast and may be commonly seen on breast MRI. We performed this study to identify MRI characteristics of pure FCC on MRI-guided vacuum-assisted breast biopsy (VABB) without other associated pathologies and describe the findings on MRI follow-up and outcomes.

METHODS

A retrospective review was performed for 598 lesions undergoing 9-gauge MRI-guided VABB at our institution from January 2015 to April 2018, identifying 49 pure FCC lesions in 43 patients. The associations between variables and lesion changes on follow-up MRI were analyzed using exact Mann-Whitney tests and Fisher's exact tests.

RESULTS

MRI features of pure FCC are predominantly clumped nonmass enhancement (19/49, 39%) or irregular masses with initial fast/late washout kinetics (9/49, 18%). There was no upgrade to high-risk or cancerous lesions among the 11 patients (25.6%) who underwent surgery. There were 22 pure FCC lesions in 19 (44.2%) patients who had follow-up MRI (mean 18.0 months, range 11-41 months) showing regression (13, 59%), stability (8, 36%), or progression (1, 5%) of the lesion size, and no cancers were found on follow-up at the site of the MRI biopsy for fibrocystic changes. No patient demographics or lesion features were associated with lesion regression or stability (P > 0.05).

CONCLUSION

Our study shows that MRI features of VABB-proven FCC lesions may mimic malignancy. After VABB of pure FCC, given that adequate sampling has been performed, a 12-month follow-up MRI may be reasonable.

High-risk lesions diagnosed at MRI-guided vacuum-assisted breast biopsy: imaging characteristics, outcome of surgical excision or imaging follow-up

BACKGROUND

To evaluate imaging characteristics, outcome of surgical excision or imaging follow-up on high-risk lesions diagnosed at MRI-guided vacuum-assisted breast biopsy (MRI-VABB).

METHODS

We retrospectively reviewed 598 lesions undergoing 9-gauge MRI-VABB from January 2015 to April 2018 to identify high risk breast lesions. We collected patient demographics, breast MRI BI-RADS descriptors, histopathological diagnosis at MRI-VABB and surgical excision, frequency of upgrade to malignancy and imaging follow-up of high-risk lesions. The x² test and Fisher exact tests were performed for univariate analysis.

RESULTS

114 patients with 124/598 findings (20.7%) had high-risk lesions at MRI-VABB, including atypical ductal hyperplasia (ADH) (21/124, 16.9%), lobular neoplasia (40/124, 32.3%), radial scar/complex sclerosing lesion (RS/CSL) (13/124, 10.5%), papillary lesions (49/124, 39.5%), and flat epithelial atypia (FEA) (1/124, 0.8%). 84/124 (67.7%) high-risk lesions were excised. 19/84 (22.6%) were upgraded to malignancy (7 invasive cancer, 12 DCIS). The upgrade rate for ADH and lobular neoplasia was 7/18 (38.9%) and 9/31 (29.0%), respectively. The upgrade rate for RS/CSL was 1/10 (10%). Of the 25 papillary lesions excised, 2 (8%) demonstrated pathologic atypia and were upgraded to DCIS. The other 23 papillary lesions had no upgrade or atypia. Excised high-risk lesions showing upgrade varied from 0.4 to 6 cm in length (mean 1.6 cm). There was a non-significant trend (p = 0.054) between larger lesion and upgrade to malignancy; however, there were no other specific imaging features to predict malignancy upgrade.

CONCLUSIONS

There were no specific MRI imaging characteristics of high-risk lesions to predict malignancy upgrade. Therefore, surgical excision is recommended for high-risk lesions, especially ADH or lobular neoplasia.

Radiomics features to identify distinct subtypes of triple-negative breast cancers

3069

Background: We sought to gain new insight into triple-negative breast cancer (TNBC), an aggressive, clinically distinct subgroup of breast cancers, by applying a sequence of computational approaches to tumor segmentation, three-dimensional anatomic characterization, and tumor subtyping. We extracted algorithmically-derived quantitative imaging (radiomics) features from each TNBC lesion in breast magnetic resonance imaging (MRI) to identify underlying subtypes. Methods: We evaluated tumors on pre-treatment, post-contrast MRI from 90 patients with non-metastatic TNBC. We employed active contour segmentation and semi-automated identification of tumor regions-of-interest. We extracted 900 radiomics features from each segmented tumor using an algorithm that characterizes the size, shape, texture, and edge sharpness of tumors at the voxel level. We applied k-means consensus clustering, a statistical tool for unsupervised discovery, and performed 1000 bootstraps with resampling on the feature vectors to examine all resulting clusters from k=2 to 10. Based on two diagnostic metrics of consensus stability, we selected the optimum cluster number. We performed Significance Analysis of Microarrays to identify statistically significant radiomics features for each cluster. Results: We identified three distinct image-based clusters in 117 tumors from 90 TNBC patients (multifocal lesions in n=13). Cluster 1 (n=97) was distinguished by 330 radiomics features (False Discovery Rate [FDR] <5%) and Cluster 2 (n=13) by 85 features (FDR<5%), whereas Cluster 3 (n=7) was not significantly associated with features. Clinical characteristics did not differ across the three clusters, with mean age (49.1±11.7) and clinical stage distributions (stage I: 20.7%, II: 55.4%, III: 23.9%) for the cohort mirroring those of individual clusters. Among those who received neoadjuvant therapy, we observed pathologic complete response in 50% (23 of 46, 95% CI, 0.36-0.64) of patients in Cluster 1, 83% (5 of 6, 95% CI, 0.54-1.0) in Cluster 2, and 0% (0 of 3) in Cluster 3. Conclusions: Radiomics features providing voxel-level characteristics of tumor morphology differentiated TNBC into three distinct subtypes. These subtypes, defined by radiomics biomarkers, may be associated with clinical response to neoadjuvant therapy.

Abstract PD4-02: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Wong MJ, Patel R, DeMartini WB, Todderud JE, Okamoto S, Ikeda DM. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD4-02.

Impact of physiological hormonal fluctuations on 18F-fluorodeoxyglucose uptake in breast cancer

PURPOSE

Premenopausal physiologic steroid levels change cyclically, in contrast to steady state low levels seen in postmenopausal patients. The purpose of this study was to evaluate whether ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake in breast cancer is influenced by physiological hormonal fluctuations.

METHODS

A total of 160 primary invasive breast cancers from 155 females (54 premenopausal, 101 postmenopausal) who underwent ¹⁸F-FDG positron emission tomography/computed tomography before therapy were retrospectively analyzed. The maximal standardized uptake values (SUVmax) of tumors were compared with menstrual phases and menopausal status according to the following subgroups: 'luminal A-like,' 'luminal B-like,' and 'non-luminal.' Additionally, the effect of estradiol (E2) on ¹⁸F-FDG uptake in breast cancer cells was evaluated in vitro.

RESULTS

Among premenopausal patients, SUVmax during the periovulatory-luteal phase was significantly higher than that during the follicular phase in luminal A-like tumors (n = 25, p = 0.004), while it did not differ between the follicular phase and the periovulatory-luteal phase in luminal B-like (n = 24) and non-luminal tumors (n = 7). Multiple regression analysis showed menstrual phase, tumor size, and Ki-67 index are independent predictors for SUVmax in premenopausal luminal A-like tumors. There were no significant differences in SUVmax between pre- and postmenopausal patients in any of the subgroups. In in vitro studies, uptake in estrogen receptor-positive cells was significantly augmented when E2 concentration was increased from 0.01 to ≥ 1 nM.

CONCLUSIONS

Our data suggest that ¹⁸F-FDG uptake may be impacted by physiological hormonal fluctuations during menstrual cycle in luminal A-like cancers, and that E2 could be partly responsible for these events.

Heterogeneous Enhancement Patterns of Tumor-adjacent Parenchyma at MR Imaging Are Associated with Dysregulated Signaling Pathways and Poor Survival in Breast Cancer

Purpose To identify the molecular basis of quantitative imaging characteristics of tumor-adjacent parenchyma at dynamic contrast material-enhanced magnetic resonance (MR) imaging and to evaluate their prognostic value in breast cancer. Materials and Methods In this institutional review board-approved, HIPAA-compliant study, 10 quantitative imaging features depicting tumor-adjacent parenchymal enhancement patterns were extracted and screened for prognostic features in a discovery cohort of 60 patients. By using data from The Cancer Genome Atlas (TCGA), a radiogenomic map for the tumor-adjacent parenchymal tissue was created and molecular pathways associated with prognostic parenchymal imaging features were identified. Furthermore, a multigene signature of the parenchymal imaging feature was built in a training cohort (n = 126), and its prognostic relevance was evaluated in two independent cohorts (n = 879 and 159). Results One image feature measuring heterogeneity (ie, information measure of correlation) was significantly associated with prognosis (false-discovery rate < 0.1), and at a cutoff of 0.57 stratified patients into two groups with different recurrence-free survival rates (log-rank P = .024). The tumor necrosis factor signaling pathway was identified as the top enriched pathway (hypergeometric P < .0001) among genes associated with the image feature. A 73-gene signature based on the tumor profiles in TCGA achieved good association with the tumor-adjacent parenchymal image feature (R² = 0.873), which stratified patients into groups regarding recurrence-free survival (log-rank P = .029) and overall survival (log-rank P = .042) in an independent TCGA cohort. The prognostic value was confirmed in another independent cohort (Gene Expression Omnibus GSE 1456), with log-rank P = .00058 for recurrence-free survival and log-rank P = .0026 for overall survival. Conclusion Heterogeneous enhancement patterns of tumor-adjacent parenchyma at MR imaging are associated with the tumor necrosis signaling pathway and poor survival in breast cancer. ^© RSNA, 2017 Online supplemental material is available for this article.

Unsupervised Clustering of Quantitative Image Phenotypes Reveals Breast Cancer Subtypes with Distinct Prognoses and Molecular Pathways

Purpose: To identify novel breast cancer subtypes by extracting quantitative imaging phenotypes of the tumor and surrounding parenchyma and to elucidate the underlying biologic underpinnings and evaluate the prognostic capacity for predicting recurrence-free survival (RFS).Experimental Design: We retrospectively analyzed dynamic contrast-enhanced MRI data of patients from a single-center discovery cohort (n = 60) and an independent multicenter validation cohort (n = 96). Quantitative image features were extracted to characterize tumor morphology, intratumor heterogeneity of contrast agent wash-in/wash-out patterns, and tumor-surrounding parenchyma enhancement. On the basis of these image features, we used unsupervised consensus clustering to identify robust imaging subtypes and evaluated their clinical and biologic relevance. We built a gene expression-based classifier of imaging subtypes and tested their prognostic significance in five additional cohorts with publically available gene expression data but without imaging data (n = 1,160).Results: Three distinct imaging subtypes, that is, homogeneous intratumoral enhancing, minimal parenchymal enhancing, and prominent parenchymal enhancing, were identified and validated. In the discovery cohort, imaging subtypes stratified patients with significantly different 5-year RFS rates of 79.6%, 65.2%, 52.5% (log-rank P = 0.025) and remained as an independent predictor after adjusting for clinicopathologic factors (HR, 2.79; P = 0.016). The prognostic value of imaging subtypes was further validated in five independent gene expression cohorts, with average 5-year RFS rates of 88.1%, 74.0%, 59.5% (log-rank P from <0.0001 to 0.008). Each imaging subtype was associated with specific dysregulated molecular pathways that can be therapeutically targeted.Conclusions: Imaging subtypes provide complimentary value to established histopathologic or molecular subtypes and may help stratify patients with breast cancer. Clin Cancer Res; 23(13); 3334-42. ©2017 AACR.

Abstract P3-01-03: Milky Way sign: A potential predictive sign of breast cancer on digital breast tomosynthesis

Purpose: “Milky Way sign (MWS)”, which we recently reported1), is a new finding on digital breast tomosynthesis (DBT) showing microcalcifications overlying non-calcified band-like density. Our study purpose was to describe frequencies of and imaging findings associated with MWS, and to examine the predictive value of MWS for breast cancer.

Materials and Methods: We reviewed all stereotactic core biopsies of suspicious calcifications at our institution from 1/1/2015 to 12/31/2015, finding 124 lesions with calcifications, including 20 malignancies (2 IDC, 5 IDC+DCIS, 13 DCIS) and 104 non-malignant lesions (23 high-risk [14 ADH, 6 LCIS/ALH, 1 intraductal papilloma, 2 other atypical], 81 benign), in 116 patients undergoing both 2D mammogram and DBT before biopsies. 2 radiologists reviewed images for the presence of MWS, local breast density within 1 cm surrounding the calcifications, classifying BI-RADS calcification morphology and distribution. We assessed the predictive value of MWS for malignancy using Chi square test and multivariate logistic analysis.

Results: MWS was identified more frequently with DBT (27/124, 22%) than with 2D (13/124, 10%), and more in locally less dense tissue than in locally dense tissue. The calcifications in MWS were fine pleomorphic (13/27, 48%), amorphous (8/27, 30%), fine linear/branching (5/27, 19%), or other (1/27, 4%), with distributions of grouped (20/27, 74%), linear (5/27, 19%) or segmental (2/27, 7%) categories. MWS on DBT was observed in 60% (12/20, including 2 IDC, 2 IDC+DCIS, 8 DCIS) of malignant lesions and 14% (15/104) of benign lesions (table1), and was significantly and positively associated with malignant lesions (p &lt; .001). Multivariate analysis demonstrated the MWS on DBT (p &lt; .001) and fine linear/branching calcifications (p &lt; .001) were independent predictors for malignancy.

Frequencies of MWS on DBT according to histopathology nMWS positiveMWS negativeMalignancy2012 (60)8 (40)-IDC22 (100)0 (0)-IDC+DCIS52 (40)3 (60)-DCIS138 (62)5 (38)Non-malignant lesion10415 (14)89 (86)-ADH143 (21)11 (79)-LCIS/ALH60 (0)6 (100)-Intraductal papilloma10 (0)1 (100)-Other high-risk20 (0)2 (100)-Benign8112 (15)69 (85)Total12427 (22)97 (78)Data are shown as number with percentage in parenthesis.

Conclusions: Although sample size was limited, our results indicate that DBT may contribute in detecting MWS, and that MWS may be a predictive sign for breast cancers, leading to biopsy of suspicious calcifications.

Reference 1) Xu Y, Miyake KK, Liu YI, Downey JR, Lipson J, Allison K, Ikeda DM. “The Milky Way Sign: a new diagnostic findings of ductal carcinoma on digital tomosynthesis.” The Breast Journal. 2016 May; 22 (3):349-51.

Citation Format: Miyake KK, Lipson JA, Allison KH, Xu Y, Liu YI, Downey JR, Ikeda DM. Milky Way sign: A potential predictive sign of breast cancer on digital breast tomosynthesis [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-01-03.

Identifying relations between imaging phenotypes and molecular subtypes of breast cancer: Model discovery and external validation

PURPOSE

To determine whether dynamic contrast enhancement magnetic resonance imaging (DCE-MRI) characteristics of the breast tumor and background parenchyma can distinguish molecular subtypes (ie, luminal A/B or basal) of breast cancer.

MATERIALS AND METHODS

In all, 84 patients from one institution and 126 patients from The Cancer Genome Atlas (TCGA) were used for discovery and external validation, respectively. Thirty-five quantitative image features were extracted from DCE-MRI (1.5 or 3T) including morphology, texture, and volumetric features, which capture both tumor and background parenchymal enhancement (BPE) characteristics. Multiple testing was corrected using the Benjamini-Hochberg method to control the false-discovery rate (FDR). Sparse logistic regression models were built using the discovery cohort to distinguish each of the three studied molecular subtypes versus the rest, and the models were evaluated in the validation cohort.

RESULTS

On univariate analysis in discovery and validation cohorts, two features characterizing tumor and two characterizing BPE were statistically significant in separating luminal A versus nonluminal A cancers; two features characterizing tumor were statistically significant for separating luminal B; one feature characterizing tumor and one characterizing BPE reached statistical significance for distinguishing basal (Wilcoxon P < 0.05, FDR < 0.25). In discovery and validation cohorts, multivariate logistic regression models achieved an area under the receiver operator characteristic curve (AUC) of 0.71 and 0.73 for luminal A cancer, 0.67 and 0.69 for luminal B cancer, and 0.66 and 0.79 for basal cancer, respectively.

CONCLUSION

DCE-MRI characteristics of breast cancer and BPE may potentially be used to distinguish among molecular subtypes of breast cancer.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1017-1027.

Abstract P3-01-17: A technique for preoperative axillary lymph node tattooing in patients with breast cancer

Purpose: To describe the ultrasound technique for tattooing axillary lymph nodes (ALNs) after lymph node (LN) biopsy in patients with breast cancer.

Background: Preoperative evaluation of metastatic disease within ALNs in patients with newly diagnosed breast cancer has significant prognostic value and is quickly becoming routine, particularly in the neoadjuvant setting. A recent study showed tattooed LNs are visible intraoperatively and on histological evaluation months following the tattooing procedure. These results suggest that LN tattooing can obviate the need for additional localization procedures during axillary staging, such as wire localization. Given the increasing use of preoperative ALN biopsy, a robust technique to insure proper LN tattoo marking is proposed.

Methods and Technique: Tattooing was performed under real-time US guidance using a 5-cm long 21-gauge hypodermic needle attached to a 1 mL tuberculin syringe containing 1 mL carbon suspension tattoo ink (SPOT™, GI-supply Inc).

Imaging was performed with the patient in a supine oblique position with the patient's arm over their head. The anatomically anterior and lateral aspects of the node and perinodal fat were marked with ink. The only regions of the LN not targeted for ink tattooing were the hilum and the posterior cortex and perinodal fat. At least 0.5 mL of ink was used.

Results: Optimal technique for intraoperative visualization was determined to be tattooing the anatomically anterior and lateral aspects of the LN cortex and the adjacent perinodal fat using at least 0.5mL of ink.

Tattooed LNs which had undergone biopsy and tattooing months prior to surgery were visible intraoperatively and on histological evaluation.

Factors contributing to less optimal visualization of the tattooed lymph node included: using less than 0.5mL of ink, tattooing only the superficial cortex and not the perinodal fat, and tattooing a portion of the LN that was not visible with the patient in the operative position.

Discussion: The most easily accessed portion of the LN during the US procedure may not be the portion of the LN most easily seen intraoperatively. Locating and tattooing the anatomically anterior and lateral aspects of the LN, regardless of the patient position and orientation of the ultrasound probe, is the primary challenge. Doing so will maximize the likelihood that the tattoo ink will be visible by the surgeon when the patient is in a supine position with the arm abducted 90 degrees using an axillary incision.

Tattooing using less than 0.5 mL resulted in suboptimal visualization. Using a larger volume of ink may be judged necessary for larger LNs, very fatty axillae, and for deeply seated nodes.

Other reports in the medical literature suggest cutaneous tattooing can result in ink within ALNs. In patients with ipsilateral cutaneous tattoos, an alternative method of marking any biopsied LNs should be considered to avoid false positives associated with prior migration of the cutaneous tattoo ink to the LN.

Tattooing of ALNs under ultrasound guidance is a straightforward technique which can be performed at the time of initial biopsy and obviates the need for future preoperative wire localization of the LN.

Citation Format: Wapnir IL, Downey JR, Lipson JA, Ikeda DM. A technique for preoperative axillary lymph node tattooing in patients with breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-01-17.

Abstract P4-01-01: A case series of the Milky Way sign: A diagnostic finding of ductal carcinoma in situ (DCIS) and invasive breast carcinoma (IDC) on digital breast tomosynthesis (DBT)

Purpose: we have previously described the "Milky Way Sign", which manifests as microcalcifications overlying noncalcified band-like density, best seen in digital breast tomosynthesis (DBT), in a patient with ductal carcinoma in situ (DCIS). Here, we describe a series of patients with DCIS, IDC, and rarely, Atypical Ductal Hyperplasia (ADH) with this sign.

Materials and Methods: we performed a systemic search of all stereotactic core biopsies for suspicious calcifications performed at our institution from April 15, 2014, when we first implemented DBT with synthesized 2D mammogram, to October 2, 2014, and identified all cases that were diagnosed as DCIS, IDC, or high-risk lesions (such as ADH, atypical lobular hyperplasia (ALH), and intraductal papilloma) on pathology. From 89 biopsied performed in 87 patients, a total of 13 cases of DCIS, IDC, or IDC with DCIS were identified in 12 patients. 17 cases of high-risk lesions were identified in 16 patients, including 10 ADH in 9 patients, 4 ALH, two intraductal papillomas, and one atypical columnar cell change.

Results: Among the 30 cases of suspicious calcifications with a diagnosis of DCIS, IDC, or high-risk lesions, 37% demonstrated the Milky Way Sign (11/30), including 71% of DCIS cases (5/7), 60% of cases of IDC (3/5), 100% of DCIS/IDC (1/1), and 12% of high-risk lesions (2/17). Both high-risk lesions with the Milky Way sign were ADH from the same patient. Among the 11 cases with the Milky Way sign, the breast density at the site of calcifications is either scattered (6/11) or heterogeneously dense (5/11), whereas the density at 1 cm surrounding the calcifications is either fatty (8/11) or scattered (3/11). The breast is less dense surrounding the calcifications in all but one case. The calcifications seen in the Milky Way cases are predominantly fine pleomorphic calcifications except one case of fine linear and linear branching calcifications. The calcifications are grouped (6/11), linear (3/11), or segmental (2/11) in distribution. Five patients also had contrast-enhanced breast MRIs. Among them, three (one each with the diagnosis of DCIS, IDC or DCIS/IDC) had non-mass enhancement on breast MRI that correlated to the Milky Way sign seen on mammogram. The other two patients (one with DCIS and one with IDC) had post biopsy change instead of Non-mass enhancement were seen in the corresponding areas.

Conclusion: The Milky Way sign, in the context of DBT, is a novel diagnostic sign for both DCIS and IDC. It may occasionally be seen in ADH cases as well. Features that often associate with the Milky Way sign include less dense tissue surrounding the calcifications, calcifications that are fine pleomorphic in morphology and grouped or linear in distribution. Preliminary results also suggest that the Milky Way sign may correspond to non-mass enhancement seen on contrast-enhanced breast MRI.

Clinical Relevance Statement: We hope that the Milky Way sign will facilitate detection of both DCIS and IDC in the context of DBT.

Citation Format: Allison K, Xu Y, Liu YI, Miyake KK, Downey JR, Lipson JA, Ikeda DM. A case series of the Milky Way sign: A diagnostic finding of ductal carcinoma in situ (DCIS) and invasive breast carcinoma (IDC) on digital breast tomosynthesis (DBT). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-01-01.

Abstract P4-01-05: Improving the quality of mammographic positioning

Purpose:

Optimal breast positioning is a key component to high quality screening mammograms to allow the radiologist to make the best interpretation for the patient and referring physician. In addition, the success of newer imaging techniques also depends on breast positioning. The American College of Radiology (ACR) sets the standard of what images should include by outlining 13 criteria of breast positioning. An initial audit of over 100 mammograms at our institution in 2013 found that only a mean of 33% were achieving the ACR criteria. The goal of our project was to increase the percentage of screening mammograms achieving ACR criteria to 90% by June 2015.

Methods:

Our breast imaging center partnered with a quality improvement (QI) team driving a radiology department-wide program on quality improvement. Team members identified 5 key causes that barred achieving the ACR criteria: disagreement on what meets criteria, not having a standard work for acquiring and reading mammograms, lack of communication between the technologist and radiologist, not having a measurement system to track performance, and lack of coaching on technologist techniques for acquiring images. Developments to address these causes included: teaching modules on what meets ACR criteria, standard work for radiologists to recall mammograms that did not meet ACR criteria, system for the technologist to document why criteria were missed, auditing system to track performance, and feedback sessions between technologists and radiologists. Over 1,700 mammograms were audited from the time period of July 2014 to March 2015.

Results:

By October 2014, the percentage of mammograms achieving all 13 of the ACR criteria was 71%, with 4 criteria that prevented reaching the 90% goal. By March 2015, 10 of the 13 ACR criteria were being sustainably met by the target goal of 90% of mammograms, better in all criteria compared to our 2013 data, and better in all but one criterion compared to published 1993 data. Table 1 demonstrates that we have been able to sustain a composite percentage of 12 of the 13 ACR criteria greater than 90% for the last 2 consecutive months.

Table 1 shows the composite percentage of mammograms achieving 12 of the 13 ACR criteria over time.2013 Baseline8/20149/201410/201411/20141/20152/20153/201564%67%77%82%83%81%95%96%The excluded, most difficult criterion (visualization of the opposite breast cleavage) has been achieved at 32% per 1993 published data; we currently achieve it at 40%. 12/2014 audits were not performed due to holidays and changes in staffing.

Conclusion:

Few institutions have published positioning data, with the most recent QI publication on breast positioning dating to 1993. We have conducted a structured process to improve quality of mammographic positioning, including revision of processes that led to poor positioning outcomes and creation of an environment to sustain our improved outcomes. Three ACR criteria continue to be problematic in reaching the 90% goal, with future investigation into whether it is actually feasible to achieve the most difficult criterion at our goal of 90%. Future work also includes assessing how the recent hire of a mammography coach to spread best practices and real-time feedback is able to further improve results and maintain the infrastructure of ongoing QI.

Citation Format: Chen CA, Strain A, Mickelsen JL, Larson DA, Jesinger RA, Botelho D, Fromholz S, Obi CN, Crawley A, Lipson JA, Ikeda DM, Cooper C, Pal S. Improving the quality of mammographic positioning. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-01-05.

Abstract P3-02-02: Impact of breast density notification laws on radiology practices: A survey of 110 radiology facilities

Purpose: Breast Density Notification laws, passed in 15 states as of April 2014, mandate that breast density information be given to patients often without guidance on modalities, patient selection or funding for supplemental screening. The purpose of this study is to assess the impact of breast density notification laws on radiology practices, specifically regarding breast cancer risk assessment and supplemental screening studies.

Methods:

We performed an anonymous 20-question web-based survey to Society of Breast Imaging radiologists using a Qualtrics Survey Tool between 8/2013-3/2014, with questions on radiology practices, breast cancer risk assessment, breast density measurement, supplemental screening tests, and support for referring physicians and patients. We compared survey results between groups using Fisher’s exact test.

Results:

121 radiologists from 110 facilities (48 academic, 43 large private hospital, 15 small private hospital and 4 other) representing 34 USA states and 1 Canadian site responded. 49% of facilities (54/110) were in states with an enacted breast density notification law. 37% of facilities (40/109) performed risk assessment, 26% (28/109) did not perform risk assessment, and 38% (41/109) did not but reported family history/other risk factors, with no significant difference in performing risk assessment between facilities with or without an enacted law (p-value 0.71). Of the 37 facilities performing risk assessment, 60% used the Gail model, 22% used the Tyrer-Cuzick model and 11% used the modified Gail model (multiple answers allowed [m.a.a.]). Of the 15 facilities performing risk assessment, 40% answered "yes" when asked whether performing risk assessment is a new task because of the density law. Breast density was estimated by only visual assessment in 98% of facilities (103/105), and by computer-based determination with or without visual assessment in 2% (2/105). Supplemental screening studies offered included magnetic resonance imaging (MRI) (88%, 92/105), handheld whole breast ultrasound (HHWBUS) (48%, 50/105), tomosynthesis (39%, 41/105), and automated WBUS (8%, 8/105) (m.a.a.). There was no significant difference in supplemental screening studies offered between facilities with or without an enacted law (p-value 0.26). In anticipation of the law, facilities implemented HHWBUS (33%, 16/48), tomosynthesis (6%, 3/48), automated WBUS (6%, 3/48) or none (60%, 29/48) (m.a.a.). Facilities with the enacted law prepared for the law with referring physician discussions (69%, 34/49), website (49%, 24/49), educational talks for referring physicians (43%, 21/49) or patients (31%, 15/49) (m.a.a.).

Conclusion:

Our survey showed variations in available supplemental screening modalities and policy implementation at each facility. There was no significant difference in performing risk assessment and supplemental screening studies between facilities with or without an enacted breast density notification law.

Citation Format: Lina Nayak, Kanae K Miyake, Yueyi Irene Liu, William R Thomas, Edward A Sickles, Bonnie N Joe, Karen Lindfors, R J Brenner, Stephen Feig, Lawrence W Bassett, Jessica W Leung, Haydee Ojeda-Fournier, Jonathan Hargreaves, Elissa Price, Jafi A Lipson, Allison W Kurian, Elyse Love, Donna D Walgenbach, Lauren Ryan, Meg Durbin, Bruce L Daniel, Linda Garcia, Debra M Ikeda. Impact of breast density notification laws on radiology practices: A survey of 110 radiology facilities [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-02-02.

Assessment of tumor morphology on diffusion-weighted (DWI) breast MRI: Diagnostic value of reduced field of view DWI

PURPOSE

To compare the diagnostic value of conventional, bilateral diffusion-weighted imaging (DWI) and high-resolution targeted DWI of known breast lesions.

MATERIALS AND METHODS

Twenty-one consecutive patients with known breast cancer or suspicious breast lesions were scanned with the conventional bilateral DWI technique, a high-resolution, reduced field of view (rFOV) DWI technique, and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) (3.0 T). We compared bilateral DWI and rFOV DWI quantitatively by measuring the lesions' apparent diffusion coefficient (ADC) values. For qualitative comparison, three dedicated breast radiologists scored image quality and performed lesion interpretation.

RESULTS

In a phantom, ADC values were in good agreement with the reference values. Twenty-one patients (30 lesions: 14 invasive carcinomas, 10 benign lesions [of which 5 cysts], 3 high-risk, and 3 in situ carcinomas) were included. Cysts and high-risk lesions were excluded from the quantitative analysis. Quantitatively, both bilateral and rFOV DWI measured lower ADC values in invasive tumors than other lesions. In vivo, rFOV DWI gave lower ADC values than bilateral DWI (1.11 × 10(-3) mm(2) /s vs. 1.24 × 10(-3) mm(2) /s, P = 0.002). Regions of interest (ROIs) were comparable in size between the two techniques (2.90 vs. 2.13 cm(2) , P = 0.721). Qualitatively, all three radiologists scored sharpness of rFOV DWI images as significantly higher than bilateral DWI (P ≤ 0.002). Receiver operating characteristic (ROC) curve analysis showed a higher area under the curve (AUC) in BI-RADS classification for rFOV DWI compared to bilateral DWI (0.71 to 0.93 vs. 0.61 to 0.76, respectively).

CONCLUSION

Tumor morphology can be assessed in more detail with high-resolution DWI (rFOV) than with standard bilateral DWI by providing significantly sharper images.

Rim sign in breast lesions on diffusion-weighted magnetic resonance imaging: diagnostic accuracy and clinical usefulness

PURPOSE

To investigate the diagnostic accuracy and clinical usefulness of the rim sign in breast lesions observed in diffusion-weighted magnetic resonance imaging (DWI).

MATERIALS AND METHODS

The magnetic resonance imaging (MRI) findings of 98 pathologically confirmed lesions (62 malignant and 36 benign) in 84 patients were included. Five breast radiologists were asked to independently review the breast MRI results, to grade the degree of high peripheral signal, the "rim sign," in the DWI, and to confirm the mean apparent diffusion coefficient (ADCmean ) values. We analyzed the diagnostic accuracy and compared the consensus (when ≥ 4 of 5 independent reviewers agreed) results of the rim sign with the ADCmean values. Additionally, we evaluated the correlation between the dynamic contrast-enhanced (DCE)-MRI morphologic appearance and DWI rim sign.

RESULTS

According to the consensus results, the rim sign in DWI was observed on 59.7% of malignant lesions and 19.4% of benign lesions. The sensitivity, specificity, and area under the curve (AUC) value for the rim sign in DWI were 59.7%, 80.6%, and 0.701, respectively. The sensitivity, specificity, and AUC value for the ADCmean value (criteria ≤ 1.46 × 10(-3) mm(2) /sec) were 82.3%, 63.9%, and 0.731, respectively. Based on consensus, no correlation was observed between the DCE-MRI and DWI rim signs.

CONCLUSION

In DWI, a high-signal rim is a valuable morphological feature for improving specificity in DWI.

Abstract P2-01-01: Impact of California breast density notification law SB 1538 on California women and their health care providers

Purpose: To describe the impact of California Breast Density Notification law (SB 1538) on policy development, policy implementation and supplemental screening strategies within California medical facilities. SB 1538 mandates that breast density information be given to patients but provides no funding for supplemental screening, no guidance on how to triage women for supplemental screening nor which imaging modalities to use.

Methods:

As a result of the law, the California Breast Density Information Group (CBDIG) formed from academic and private practice radiologists and risk assessment experts, reviewing scientific literature and nationally recognized guidelines to provide evidence-based recommendations regarding supplemental screening in women with dense breast tissue. A survey was sent to 6 academic and 3 large private practices in California to record their experience in implementing the law.

Results: CBDIG created a public, institution-neutral, evidence-based website, “breastdensity.info”, that includes information and recommendations regarding supplemental breast screening, with triage for supplemental MRI or US based on breast cancer risk assessment using genetic or family history risk models. CBDIG facilities worked with referring health care providers to inform them of the new law, educated their staff and technologists on implementing policy, and developed notification strategies to comply with legislation.

The survey showed that all 9 facilities recommended supplemental screening based on family history models or genetic testing. 3/9 calculated breast cancer risk in the breast imaging clinic, and 2/9 emailed a risk survey to the patient. 3/9 reported risk in the radiology report, and 1/9 reported risk only if the patient was high risk. Risk assessments were performed by technologists and risk assessment health practitioners. 8/9 facilities estimated breast density by visual methods, and 1/9 by computer. All facilities performed screening breast MRI, 4/9 performed handheld screening US, and 2/9 tomosynthesis. 1/9 obtained tomosynthesis in anticipation of the law, 2/9 are trying to obtain automated whole breast US, and 3/9 are trying to obtain tomosynthesis. Facilities expressed concerns about additional false-positive biopsies produced by supplemental screenings, out-of-pocket expenses for women, and disparities (low income) in notified populations.

Conclusion: SB 1538 resulted in the formation of the CBDIG and the website, “breastdensity.info”. Our survey showed variations in imaging modalities available and policy implementation at each facility. Given that several states currently have breast density laws or have laws that will become effective in the near future, it is important for breast imagers and clinicians to be informed of the current literature, realize the variation in equipment and policies at various facilities, and develop recommendation strategies to guide patients seeking supplemental screening. We plan to follow up this survey with a larger survey of the Society of Breast Imagers at a later date.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-01-01.

The California breast density information group: a collaborative response to the issues of breast density, breast cancer risk, and breast density notification legislation

In anticipation of breast density notification legislation in the state of California, which would require notification of women with heterogeneously and extremely dense breast tissue, a working group of breast imagers and breast cancer risk specialists was formed to provide a common response framework. The California Breast Density Information Group identified key elements and implications of the law, researching scientific evidence needed to develop a robust response. In particular, issues of risk associated with dense breast tissue, masking of cancers by dense tissue on mammograms, and the efficacy, benefits, and harms of supplementary screening tests were studied and consensus reached. National guidelines and peer-reviewed published literature were used to recommend that women with dense breast tissue at screening mammography follow supplemental screening guidelines based on breast cancer risk assessment. The goal of developing educational materials for referring clinicians and patients was reached with the construction of an easily accessible Web site that contains information about breast density, breast cancer risk assessment, and supplementary imaging. This multi-institutional, multidisciplinary approach may be useful for organizations to frame responses as similar legislation is passed across the United States. Online supplemental material is available for this article.

Image quality and diagnostic performance of silicone-specific breast MRI

PURPOSE

To compare the image quality of three techniques and diagnostic performance in detecting implant rupture.

MATERIALS AND METHODS

The study included 161 implants for the evaluation of image quality, composed of water-saturated short TI inversion recovery (herein called "water-sat STIR"), three-point Dixon techniques (herein called "Dixon"), and short TI inversion recovery fast spin-echo with iterative decomposition of silicone and water using least-squares approximation (herein called "STIR IDEAL") and included 41 implants for the evaluation of diagnostic performance in detecting rupture, composed of water-sat STIR and STIR IDEAL. Six image quality categories were evaluated and three classifications were used: normal implant, possible rupture, and definite rupture.

RESULTS

Statistically significant differences were noted for the image quality categories (p<0.001). STIR IDEAL was superior or equal to water-sat STIR in all image quality categories except artifact effects and superior to Dixon in all categories. Water-sat STIR performed the poorest for water suppression uniformity. The sensitivity and specificity in detecting implant rupture of STIR-IDEAL were 81.8 % and 77.8 % and the difference between two techniques was not statistically significant.

CONCLUSION

STIR-IDEAL is a useful silicone-specific imaging technique demonstrating more robust water suppression and equivalent diagnostic accuracy for detecting implant rupture, than water-sat STIR, at the cost of longer scan time and an increase in minor motion artifacts.

Updates and revisions to the BI-RADS magnetic resonance imaging lexicon

This article summarizes the updates and revisions to the second edition of the BI-RADS MRI lexicon. A new feature in the lexicon is background parenchymal enhancement and its descriptors. Another major focus is on revised terminology for masses and non-mass enhancement. A section on breast implants and associated lexicon terms has also been added. Because diagnostic breast imaging increasingly includes multimodality evaluation, the new edition of the lexicon also contains revised recommendations for combined reporting with mammography and ultrasound if these modalities are included as comparison, and clarification on the use of final assessment categories in MR imaging.

Breast cancer risk factors differ between Asian and white women with BRCA1/2 mutations

The prevalence and penetrance of BRCA1 and BRCA2 (BRCA1/2) mutations may differ between Asians and whites. We investigated BRCA1/2 mutations and cancer risk factors in a clinic-based sample. BRCA1/2 mutation carriers were enrolled from cancer genetics clinics in Hong Kong and California according to standardized entry criteria. We compared BRCA mutation position, cancer history, hormonal and reproductive exposures. We analyzed DNA samples for single-nucleotide polymorphisms reported to modify breast cancer risk. We performed logistic regression to identify independent predictors of breast cancer. Fifty Asian women and forty-nine white American women were enrolled. BRCA1 mutations were more common among whites (67 vs. 42 %, p = 0.02), and BRCA2 mutations among Asians (58 vs. 37 %, p = 0.04). More Asians had breast cancer (76 vs. 53 %, p = 0.03); more whites had relatives with breast cancer (86 vs. 50 %, p = 0.0003). More whites than Asians had breastfed (71 vs. 42 %, p = 0.005), had high BMI (median 24.3 vs. 21.2, p = 0.04), consumed alcohol (2 drinks/week vs. 0, p < 0.001), and had oophorectomy (61 vs. 34 %, p = 0.01). Asians had a higher frequency of risk-associated alleles in MAP3K1 (88 vs. 59 %, p = 0.005) and TOX3/TNRC9 (88 vs. 55 %, p = 0.0002). On logistic regression, MAP3K1 was associated with increased breast cancer risk for BRCA2, but not BRCA1 mutation carriers; breast density was associated with increased risk among Asians but not whites. We found significant differences in breast cancer risk factors between Asian and white BRCA1/2 mutation carriers. Further investigation of racial differences in BRCA1/2 mutation epidemiology could inform targeted cancer risk-reduction strategies.

3D T2-weighted spin echo imaging in the breast

PURPOSE

To evaluate the performance of 2D versus 3D T2-weighted spin echo imaging in the breast.

MATERIALS AND METHODS

2D and 3D T2-weighted images were acquired in 25 patients as part of a clinically indicated breast magnetic resonance imaging (MRI) exam. Lesion-to-fibroglandular tissue signal ratio was measured in 16 identified lesions. Clarity of lesion morphology was assessed through a blinded review by three radiologists. Instances demonstrating the potential diagnostic contribution of 3D versus 2D T2-weighted imaging in the breast were noted through unblinded review by a fourth radiologist.

RESULTS

The lesion-to-fibroglandular tissue signal ratio was well correlated between 2D and 3D T2-weighted images (R(2)  = 0.93). Clarity of lesion morphology was significantly better with 3D T2-weighted imaging for all observers based on a McNemar test (P ≤ 0.02, P ≤ 0.01, P ≤ 0.03). Instances indicating the potential diagnostic contribution of 3D T2-weighted imaging included improved depiction of signal intensity and improved alignment between DCE and T2-weighted findings.

CONCLUSION

In this pilot study, 3D T2-weighted imaging provided comparable contrast and improved depiction of lesion morphology in the breast in comparison to 2D T2-weighted imaging. Based on these results further investigation to determine the diagnostic impact of 3D T2-weighted imaging in breast MRI is warranted.

Abstract P4-01-12: Compliance with Recommended Follow-Up after MRI-guided Core Needle Biopsy of Suspicious Breast Lesions: A Retrospective Study

Purpose: The purpose of this study was to assess patient compliance with recommended follow-up after MRI-guided core needle biopsy and investigate the reasons why patients did not comply with their recommended MRI imaging follow-up.

Materials and Methods: A HIPAA compliant retrospective review was performed of 576 MRI-guided core needle biopsies between 2007–2010 with IRB approval and waiver of informed consent. Of 576 biopsies, 73.3% (422/576) were compliant and 26.7% (154/576) were noncompliant with follow-up recommendations and composed this study. Imaging and surgical planning was determined by comparing imaging findings, clinical findings, and biopsy histology.

Results: Out of 135 lesions in patients noncompliant with follow-up imaging, 50.4% (68/135) were referred for biopsy by non-affiliated physicians, 41.5% (56/135) received a screening MRI, and 40.3% (56/135) were a focus or foci. Referring physicians provided information regarding the follow-up status of 88/154 (57%) lesions in noncompliant patients, of which 44/88 (50%) were followed by mammogram instead of MRI. Among compliant patients, 7/178 (3.9%) lesions seen on follow-up MRI were found to be high risk or malignant.

Conclusion: Compliance with follow-up MRI recommendation after core needle biopsy is low. Three characteristics were found to be associated with noncompliance with follow-up imaging: referral from non-affiliated physician, screening MRI, and a focus lesion. Moreover, patients who do not comply with recommended MRI follow-up are more likely to have follow-up mammography. Follow-up imaging among compliant patients found high-risk lesions and malignancy. Facilities performing MRI-guided core biopsies should therefore be aware of a high risk of noncompliance with follow-up.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-01-12.