Current status of optoacoustic breast imaging and future trends in clinical application: is it ready for prime time?

Optoacoustic imaging (OAI) is an emerging field with increasing applications in patients and exploratory clinical trials for breast cancer. Optoacoustic imaging (or photoacoustic imaging) employs non-ionizing, laser light to create thermoelastic expansion in tissues and detect the resulting ultrasonic emission. By combining high optical contrast capabilities with the high spatial resolution and anatomic detail of grayscale ultrasound, OAI offers unique opportunities for visualizing biological function of tissues in vivo. Over the past decade, human breast applications of OAI, including benign/malignant mass differentiation, distinguishing cancer molecular subtype, and predicting metastatic potential, have significantly increased. We discuss the current state of optoacoustic breast imaging, as well as future opportunities and clinical application trends. CLINICAL RELEVANCE STATEMENT: Optoacoustic imaging is a novel breast imaging technique that enables the assessment of breast cancer lesions and tumor biology without the risk of ionizing radiation exposure, intravenous contrast, or radionuclide injection. KEY POINTS: • Optoacoustic imaging (OAI) is a safe, non-invasive imaging technique with thriving research and high potential clinical impact. • OAI has been considered a complementary tool to current standard breast imaging techniques. • OAI combines parametric maps of molecules that absorb light and scatter acoustic waves (like hemoglobin, melanin, lipids, and water) with anatomical images, facilitating scalable and real-time molecular evaluation of tissues.

Cost-Effectiveness of an Ultrasound-First Strategy in the Diagnostic Evaluation of Noncalcified Lesions Recalled From Screening Digital Breast Tomosynthesis.

BACKGROUND. Ultrasound may be sufficient in the diagnostic evaluation of many noncalcified lesions recalled from screening digital breast tomosynthesis (DBT). In some scenarios, omission of diagnostic mammography can save health care costs. OBJECTIVE. The purpose of this study was to evaluate the cost-effectiveness of a strategy of performing ultrasound first versus diagnostic mammography first in the diagnostic evaluation of noncalcified lesions recalled from screening DBT. METHODS. Decision tree analysis was performed to compare ultrasound first versus diagnostic mammography first in the diagnostic evaluation of DBT-recalled noncalcified lesions from a U.S. health care system perspective with a 40-year horizon. The analysis used probabilities and prevalence information from published single-institution prospective data, additional literature-derived estimates of diagnostic test performance, and Medicare-allowable reimbursement rates. Health states were represented in a Markov chain model. For each strategy, the total cost and effectiveness (expressed in quality-adjusted life-years [QALYs]) were estimated. Cost-effectiveness was assessed through incremental cost-effectiveness ratios (ICERs) and incremental net monetary benefit, with use of a willingness-to-pay (WTP) threshold of US$100,000 per QALY gained. Deterministic sensitivity analyses were performed to estimate the impact of different input parameters, and probabilistic sensitivity analysis with Monte Carlo simulations was conducted to estimate the impact of combined uncertainty across parameters. RESULTS. In the base-case scenario, for diagnostic evaluation of DBT-recalled noncalcified lesions, a strategy of performing ultrasound first versus diagnostic mammography first resulted in more cost savings (total cost, US$17,672 vs US$18,323) and greater cost-effectiveness (QALYs, 23.1309 vs 23.1306) over the 40-year horizon. The ultrasound-first strategy resulted in an ICER of -2,170,000 (expressed as U.S. dollars per QALY) and an incremental net monetary benefit of US$681 versus the diagnostic mammography-first strategy. Therefore, performing ultrasound first was deemed the more cost-effective strategy at the WTP threshold. In deterministic sensitivity analyses, the most important driver of cost-effectiveness was lost utility from delayed diagnosis, followed by the relative sensitivities of ultrasound and diagnostic mammography. In probabilistic sensitivity analysis, ultrasound first was the better strategy in 93.0% of iterations. CONCLUSION. A strategy of performing ultrasound first, with or without diagnostic mammography, is more cost-effective than a traditional strategy of conducting diagnostic mammography first. CLINICAL IMPACT. This cost-effectiveness analysis supports the growing prioritization of ultrasound as the primary method for evaluating DBT-recalled noncalcified lesions.

Breast Cancer Disparity and Outcomes in Underserved Women.

Women in the United States who continue to face obstacles accessing health care are frequently termed an underserved population. Safety-net health care systems play a crucial role in mitigating health disparities and reducing burdens of disease, such as breast cancer, for underserved women. Disparities in health care are driven by various factors, including race and ethnicity, as well as socioeconomic factors that affect education, employment, housing, insurance status, and access to health care. Underserved women are more likely to be uninsured or underinsured throughout their lifetimes. Hence they have greater difficulty gaining access to breast cancer screening and are less likely to undergo supplemental imaging when needed. Therefore, underserved women often experience significant delays in the diagnosis and treatment of breast cancer, leading to higher mortality rates. Addressing disparities requires a multifaceted approach, with formal care coordination to help at-risk women navigate through screening, diagnosis, and treatment. Mobile mammography units and community outreach programs can be leveraged to increase community access and engagement, as well as improve health literacy with educational initiatives. Radiology-community partnerships, comprised of imaging practices partnered with local businesses, faith-based organizations, homeless shelters, and public service departments, are essential to establish culturally competent breast imaging care, with the goal of equitable access to early diagnosis and contemporary treatment. Published under a CC BY 4.0 license. Test Your Knowledge questions are available in the Online Learning Center. See the invited commentary by Leung in this issue.

Surviving the COVID-19 pandemic: navigating the recovery of breast imaging services in a safety-net hospital.

PURPOSE: The purpose of this study was to determine the impact of COVID-19 on county safety-net breast imaging services and describe the steps taken to actively manage and mitigate delays. METHODS: This was an IRB exempt retrospective review of our county safety-net breast imaging practice analyzed for 4 distinct time periods: (1) "Shut-down period": March 17, 2020 to May 17, 2020; (2) "Phased re-opening": May 18, 2020 to June 30, 2020; (3) "Ramp-up": July 1, 2020 to September 30, 2020; and (4) "Current state": October 1, 2020 to September 30, 2021. These time periods were compared to identical time periods 1 year prior. For "Current state," given that the 1-year prior comparison encompassed the first 3 periods of the pandemic, the identical time period 2 years prior was also compared. RESULTS: Our safety-net practice sustained significant volume losses during the first 3 time periods with a 99% reduction in screening mammography in the shut-down period. Cancers diagnosed decreased by 17% in 2020 (n = 229) compared to 2019 (n = 276). By implementing multiple initiatives that targeted improved access to care, including building community-hospital partnerships and engagement through outreach events and a community education roadshow, we were able to recover and significantly exceed our pandemic screening volumes by 48.1% (27,279 vs 18,419) from October 1, 2020 to September 30, 2021 compared to the identical time period 1 year prior, and exceed our pre-pandemic screening volume by 17.4% (27,279 vs 23,234) compared to the identical time period 2 years prior. CONCLUSION: Through specific community outreach programs and optimized navigation, our safety-net breast imaging practice was able to mitigate the impact of COVID-19 on our patient population by increasing patient engagement and breast imaging services.

Optoacoustic Imaging With Decision Support for Differentiation of Benign and Malignant Breast Masses: A 15-Reader Retrospective Study.

BACKGROUND. Overlap in ultrasound features of benign and malignant breast masses yields high rates of false-positive interpretations and benign biopsy results. Optoacoustic imaging is an ultrasound-based functional imaging technique that can increase specificity. OBJECTIVE. The purpose of this study was to compare specificity at fixed sensitivity of ultrasound images alone and of fused ultrasound and optoacoustic images evaluated with machine learning-based decision support tool (DST) assistance. METHODS. This retrospective Reader-02 study included 480 patients (mean age, 49.9 years) with 480 breast masses (180 malignant, 300 benign) that had been classified as BI-RADS category 3-5 on the basis of conventional gray-scale ultrasound findings. The patients were selected by stratified random sampling from the earlier prospective 16-site Pioneer-01 study. For that study, masses were further evaluated by ultrasound alone followed by fused ultrasound and optoacoustic imaging between December 2012 and September 2015. For the current study, 15 readers independently reviewed the previously acquired images after training in optoacoustic imaging interpretation. Readers first assigned probability of malignancy (POM) on the basis of clinical history, mammographic findings, and conventional ultrasound findings. Readers then evaluated fused ultrasound and optoacoustic images, assigned scores for ultrasound and optoacoustic imaging features, and viewed a POM prediction score derived by a machine learning-based DST before issuing final POM. Individual and mean specificities at fixed sensitivity of 98% and partial AUC (pAUC) (95-100% sensitivity) were calculated. RESULTS. Averaged across all readers, specificity at fixed sensitivity of 98% was significantly higher for fused ultrasound and optoacoustic imaging with DST assistance than for ultrasound alone (47.2% vs 38.2%; p = .03). Across all readers, pAUC was higher (p < .001) for fused ultrasound and optoacoustic imaging with DST assistance (0.024 [95% CI, 0.023-0.026]) than for ultrasound alone (0.021 [95% CI, 0.019-0.022]). Better performance using fused ultrasound and optoacoustic imaging with DST assistance than using ultrasound alone was observed for 14 of 15 readers for specificity at fixed sensitivity and for 15 of 15 readers for pAUC. CONCLUSION. Fused ultrasound and optoacoustic imaging with DST assistance had significantly higher specificity at fixed sensitivity than did conventional ultrasound alone. CLINICAL IMPACT. Optoacoustic imaging, integrated with reader training and DST assistance, may help reduce the frequency of biopsy of benign breast masses.

Outcome of Imaging and Biopsy of BI-RADS Category 3 Lesions: Follow-Up Compliance, Biopsy, and Malignancy Rates in a Large Patient Cohort.

OBJECTIVES: To identify biopsy rates and indications for BI-RADS 3 lesions in a large cohort of patients and compare with follow-up compliance and malignancy outcomes. METHODS: We retrospectively reviewed all BI-RADS category-3 lesions seen on mammography and/or ultrasound between 2013 and 2015. Patient age, lesion size, follow-up rates at 6-, 12-, and 24-months were collected. Biopsy timing, indication, and outcomes (malignant vs benign) were recorded using at least 2-year follow-up or biopsy pathology as endpoint. RESULTS: Of 2319 BI-RADS 3 lesions in 2075 women analyzed, biopsy was performed in 173 (7.5%). Most biopsies were performed upfront (99, 57.2%), followed by at 6 (44, 25.4%), 12 (21, 12.1%), and 24-month follow-up (9, 5.2%; P < .001). Palpable (P < .001) and larger (median 1.4 vs 1.0 cm, P < .001) lesions in women <40 years (15.2% vs 4.8%, P < .001) were more likely to undergo biopsy. Most biopsies were prompted by patient/physician desire (64.5%, P < .001). Of 783 lesions with available endpoint, 5 (0.6%) were cancer. All cancers were identified either at presentation (in 0-5 months, n = 1) or 6-month follow-up (in 5-9 months, n = 4) with biopsy prompted by either morphology change (n = 3) or lesion growth (n = 2). Of the 1855 lesions which were expected for follow up, only 310 (16.7%) underwent all follow-ups, while 482 (26.1%) had two, 489 (26.5%) one, and 565 (30.6%) had no follow-up. CONCLUSIONS: In our cohort, BI-RADS category 3 lesions had significantly higher biopsy rates compared with the small malignancy rate, all of which were identified at baseline or first follow-up. Overall patient follow-up compliance low. Imaging follow-up, especially at first 6-month time point, should be encouraged in BI-RADS 3 lesions, instead of upfront biopsies.

Diagnostic Evaluation of Recalled Noncalcified Lesions Using Ultrasound Alone Versus Ultrasound Plus Additional Mammographic Views: A Prospective Study.

BACKGROUND. The diagnostic performance of digital breast tomosynthesis (DBT) has been shown to be equal to that of diagnostic mammography. However, the value of additional mammographic views in diagnostic evaluations remains unclear. OBJECTIVE. The purpose of this study was to compare the performance of diagnostic breast ultrasound (US) alone with that of combined US and diagnostic mammography for specific noncalcified recalled abnormalities detected on screening DBT. METHODS. This was a prospective study with a single-arm management strategy. Women recalled for noncalcified lesions on screening DBT underwent initial diagnostic US as part of the study protocol. Additional diagnostic mammography was performed at the discretion of the radiologist. Imaging assessment decisions determined by BI-RADS assessments and management recommendations, biopsy outcomes, and follow-up were recorded using case report forms completed on the day of the diagnostic evaluation and stored in the electronic medical record. RESULTS. From July 10, 2017, to June 6, 2019, a total of 430 recalled noncalcified lesions in 399 women (mean age, 60 ± 12 [SD] years) were included. US alone was performed for 71.2% (306/430) of lesions, whereas US with diagnostic mammography was performed for 28.8% (124/430). Of the recalled lesions, 93.7% (178/190) of masses, 60.0% (51/85) of focal asymmetries, 46.1% (53/115) of asymmetries, 69.2% (9/13) of developing asymmetries, and 55.6% (15/27) of architectural distortions were evaluated with US alone. Of 93 lesions that underwent needle biopsy, 40.9% (38/93) were cancers, all of which were invasive. Thirty-five of 38 (92.1%) cancers were evaluated by US alone, whereas three (7.9%) were evaluated with US and diagnostic mammography. At a median follow-up of 25 months, six cancers were identified (three with US alone and three with US plus diagnostic mammography) in patients with initially benign workup. US alone had two false-negative cancers (one architectural distortion identified at follow-up and one mass biopsied stereotactically at initial detection). CONCLUSION. US alone is effective in the diagnostic evaluation of noncalcified masses recalled on screening tomosynthesis. For asymmetries, diagnostic mammography may be best without the need for additional US, whereas architectural distortions still warrant diagnostic mammography and US. CLINICAL IMPACT. Radiologists should consider performing US first for DBT-recalled noncalcified masses. Omitting diagnostic mammography when US is negative has a low false-negative rate.

Performance of a clinical and imaging-based multivariate model as decision support tool to help save unnecessary surgeries for high-risk breast lesions.

PURPOSE: To investigate the performance of an imaging and biopsy parameters-based multivariate model in decreasing unnecessary surgeries for high-risk breast lesions. METHODS: In an IRB-approved study, we retrospectively reviewed all high-risk lesions (HRL) identified at imaging-guided biopsy in our institution between July 1, 2014-July 1, 2017. Lesions were categorized high-risk-I (HR-I = atypical ductal hyperplasia, atypical lobular hyperplasia, lobular carcinoma in situ and atypical papillary lesion) and II (HR-II = Flat epithelial atypia, radial scar, benign papilloma). Patient risk factors, lesion features, detection and biopsy modality, excision and cancer upgrade rates were collected. Reference standard for upgrade was either excision or at least 2-year imaging follow-up. Multiple logistic regression analysis was performed to develop a multivariate model using HRL type, lesion and biopsy needle size for surgical cancer upgrade with performance assessed using ROC analysis. RESULTS: Of 699 HRL in 652 patients, 525(75%) had reference standard available, and 48/525(9.1%) showed cancer at surgical excision. Excision (84.5% vs 51.1%) and upgrade (17.6%vs1.8%) rates were higher in HR-I compared to HR-II (p < 0.01). In HR-I, small needle size < 12G vs ≥ 12G [32.1% vs 13.2%, p < 0.01] and less cores [< 6 vs ≥ 6, 28.6%vs13.7%, p = 0.01] were significantly associated with higher cancer upgrades. Our multivariate model had an AUC = 0.87, saving 28.1% of benign surgeries with 100% sensitivity, based on HRL subtype, lesion size(mm, continuous), needle size (< 12G vs ≥ 12G) and biopsy modality (US vs MRI vs stereotactic) CONCLUSION: Our multivariate model using lesion size, needle size and patient age had a high diagnostic performance in decreasing unnecessary surgeries and shows promise as a decision support tool.

Mean Apparent Diffusion Coefficient Is a Sufficient Conventional Diffusion-weighted MRI Metric to Improve Breast MRI Diagnostic Performance: Results from the ECOG-ACRIN Cancer Research Group A6702 Diffusion Imaging Trial.

Background The Eastern Cooperative Oncology Group and American College of Radiology Imaging Network Cancer Research Group A6702 multicenter trial helped confirm the potential of diffusion-weighted MRI for improving differential diagnosis of suspicious breast abnormalities and reducing unnecessary biopsies. A prespecified secondary objective was to explore the relative value of different approaches for quantitative assessment of lesions at diffusion-weighted MRI. Purpose To determine whether alternate calculations of apparent diffusion coefficient (ADC) can help further improve diagnostic performance versus mean ADC values alone for analysis of suspicious breast lesions at MRI. Materials and Methods This prospective trial (ClinicalTrials.gov identifier: NCT02022579) enrolled consecutive women (from March 2014 to April 2015) with a Breast Imaging Reporting and Data System category of 3, 4, or 5 at breast MRI. All study participants underwent standardized diffusion-weighted MRI (b = 0, 100, 600, and 800 sec/mm2). Centralized ADC measures were performed, including manually drawn whole-lesion and hotspot regions of interest, histogram metrics, normalized ADC, and variable b-value combinations. Diagnostic performance was estimated by using the area under the receiver operating characteristic curve (AUC). Reduction in biopsy rate (maintaining 100% sensitivity) was estimated according to thresholds for each ADC metric. Results Among 107 enrolled women, 81 lesions with outcomes (28 malignant and 53 benign) in 67 women (median age, 49 years; interquartile range, 41-60 years) were analyzed. Among ADC metrics tested, none improved diagnostic performance versus standard mean ADC (AUC, 0.59-0.79 vs AUC, 0.75; P = .02-.84), and maximum ADC had worse performance (AUC, 0.52; P < .001). The 25th-percentile ADC metric provided the best performance (AUC, 0.79; 95% CI: 0.70, 0.88), and a threshold using median ADC provided the greatest reduction in biopsy rate of 23.9% (95% CI: 14.8, 32.9; 16 of 67 BI-RADS category 4 and 5 lesions). Nonzero minimum b value (100, 600, and 800 sec/mm2) did not improve the AUC (0.74; P = .28), and several combinations of two b values (0 and 600, 100 and 600, 0 and 800, and 100 and 800 sec/mm2; AUC, 0.73-0.76) provided results similar to those seen with calculations of four b values (AUC, 0.75; P = .17-.87). Conclusion Mean apparent diffusion coefficient calculated with a two-b-value acquisition is a simple and sufficient diffusion-weighted MRI metric to augment diagnostic performance of breast MRI compared with more complex approaches to apparent diffusion coefficient measurement. © RSNA, 2020 Online supplemental material is available for this article.

Deep learning in breast radiology: current progress and future directions.

This review provides an overview of current applications of deep learning methods within breast radiology. The diagnostic capabilities of deep learning in breast radiology continue to improve, giving rise to the prospect that these methods may be integrated not only into detection and classification of breast lesions, but also into areas such as risk estimation and prediction of tumor responses to therapy. Remaining challenges include limited availability of high-quality data with expert annotations and ground truth determinations, the need for further validation of initial results, and unresolved medicolegal considerations. KEY POINTS: • Deep learning (DL) continues to push the boundaries of what can be accomplished by artificial intelligence (AI) in breast imaging with distinct advantages over conventional computer-aided detection. • DL-based AI has the potential to augment the capabilities of breast radiologists by improving diagnostic accuracy, increasing efficiency, and supporting clinical decision-making through prediction of prognosis and therapeutic response. • Remaining challenges to DL implementation include a paucity of prospective data on DL utilization and yet unresolved medicolegal questions regarding increasing AI utilization.

Contrast-Enhanced Digital Mammography: Technique, Clinical Applications, and Pitfalls.

OBJECTIVE. Contrast-enhanced digital mammography (CEDM) combines the high spatial resolution of mammography with the improved enhancement provided by contrast medium. In this article, CEDM technique-the current and potential clinical applications and current challenges-will be reviewed. CONCLUSION. CEDM is a promising technique in the supplemental evaluation of patients with mammographically inconclusive findings and potentially in the screening of women with mammographically dense breasts. CEDM is emerging as a cost-effective alternative to dynamic contrast-enhanced MRI to stage newly diagnosed breast cancer and evaluate response to neoadjuvant chemotherapy.

Optoacoustic Imaging and Gray-Scale US Features of Breast Cancers: Correlation with Molecular Subtypes.

Background Optoacoustic imaging can assess tumor hypoxia coregistered with US gray-scale images. The combination of optoacoustic imaging and US may have a role in distinguishing breast cancer molecular subtypes. Purpose To investigate whether optoacoustic US feature scores correlate with breast cancer molecular subtypes. Materials and Methods A total of 1972 women (with a total of 2055 breast masses) underwent prebiopsy optoacoustic US in a prospective multi-institutional study between December 2012 and September 2015. Seven readers blinded to pathologic diagnosis scored gray-scale US and optoacoustic US features of the known cancers. Optoacoustic US features within (internal) and outside of the tumor boundary (external) were scored. Immunohistochemistry findings were obtained from pathology reports. Multinomial logistic regression analysis was used to fit the US scores, adding optoacoustic US features to the model to investigate the incremental benefit of each feature. Kruskal-Wallis tests were used to analyze the relationship between molecular subtypes and feature scores. Results Among 653 invasive cancers identified in 629 women, a total of 532 cancers in 519 women, all of which had molecular markers available, were included in the analysis. Mean age ± standard deviation was 57.9 years ± 12.6. Mean total external optoacoustic US feature scores of luminal (A and B) breast cancers were higher (9.9 vs 8.8; P < .05) and total internal scores were lower (6.8 vs 7.7; P < .001) than those of triple-negative and human epidermal growth factor receptor 2-positive (HER2+) cancers. A multinomial logistic regression model showed that optoacoustic internal vessel (odds ratio [OR], 0.6; 95% confidence interval [CI]: 0.5, 0.8; P = .002), optoacoustic internal blush (OR, 0.7; 95% CI: 0.5, 0.9; P = .02), and optoacoustic internal hemoglobin (OR, 0.6; 95% CI: 0.5, 0.8; P = .001) were associated with classification of luminal versus triple-negative and HER2+ cancer subtypes. Conclusion Combined optoacoustic US imaging and gray-scale US features may help distinguish luminal breast cancers from triple-negative and human epidermal growth factor receptor 2-positive cancers. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Mann in this issue.

Diffusion-weighted MR imaging increases diagnostic accuracy of breast MR imaging for predicting axillary metastases in breast cancer patients.

PURPOSE: To evaluate the incremental value of diffusion-weighted imaging (DWI) to conventional MR imaging (CMRI) to predict ipsilateral metastatic axillary lymphadenopathy in patients with newly diagnosed breast cancer. SUBJECTS AND METHODS: In an IRB approved retrospective single-institution study, newly diagnosed consecutive breast cancer patients with pathological verification of axillary lymph node (LN) status who had undergone breast MR imaging, including DWI as part of their standard MRI between August 1, 2010, and December 31, 2010, were reviewed. Lesion size, tumor grade, and tissue prognostic factors were noted. Ipsilateral axillary LNs were evaluated using morphological criteria on CMRI. Apparent diffusion coefficient (ADC) values of suspicious ipsilateral LNs were obtained and compared with ADC values of contralateral benign axillary LNs. Receiver operating characteristic curves and multivariate logistic regression analyses were used using pathology as the gold standard. RESULTS: Eighty-five eligible patients were identified, with surgical pathology revealing 34 patients (40%) who had malignant and 51 (60%) had benign ipsilateral axillae. The sensitivity of CMRI was 79%, with a specificity of 81%, a positive predictive value (PPV) of 65%, and a negative predictive value (NPV) of 89%. On DWI, the mean ADC value was significantly lower for metastatic LNs (0.89 ± 0.18 × 10-3  mm2 /s) than for benign ipsilateral LNs (1.41 ± 0.21 × 10-3  mm2 /s; P < 0.0001). Using a cutoff ADC value of 0.985 × 10-3  mm2 /s, yielded improved sensitivity, specificity, PPV, and NPV of 83%, 98%, 95%, and 93%, respectively. CONCLUSION: Apparent diffusion coefficient values increase the specificity of CMRI for predicting ipsilateral axillary LN metastases in patients with newly diagnosed breast cancer.

MRI-guided needle localization: Indications, tips, tricks, and review of the literature.

We describe the history of, indications for, and techniques involved in MRI-guided needle localization (MRI-NL). MRI-NL continues to be a safe, effective method of sampling lesions that are only detected with MRI, particularly for anatomically challenging lesions such as those near the chest wall, the nipple, the skin, and/or in close proximity to implants.

A Pivotal Study of Optoacoustic Imaging to Diagnose Benign and Malignant Breast Masses: A New Evaluation Tool for Radiologists.

Purpose To compare the diagnostic utility of an investigational optoacoustic imaging device that fuses laser optical imaging (OA) with grayscale ultrasonography (US) to grayscale US alone in differentiating benign and malignant breast masses. Materials and Methods This prospective, 16-site study of 2105 women (study period: 12/21/2012 to 9/9/2015) compared Breast Imaging Reporting and Data System (BI-RADS) categories assigned by seven blinded independent readers to benign and malignant breast masses using OA/US versus US alone. BI-RADS 3, 4, or 5 masses assessed at diagnostic US with biopsy-proven histologic findings and BI-RADS 3 masses stable at 12 months were eligible. Independent readers reviewed US images obtained with the OA/US device, assigned a probability of malignancy (POM) and BI-RADS category, and locked results. The same independent readers then reviewed OA/US images, scored OA features, and assigned OA/US POM and a BI-RADS category. Specificity and sensitivity were calculated for US and OA/US. Benign and malignant mass upgrade and downgrade rates, positive and negative predictive values, and positive and negative likelihood ratios were compared. Results Of 2105 consented subjects with 2191 masses, 100 subjects (103 masses) were analyzed separately as a training population and excluded. An additional 202 subjects (210 masses) were excluded due to technical failures or incomplete imaging, 72 subjects (78 masses) due to protocol deviations, and 41 subjects (43 masses) due to high-risk histologic results. Of 1690 subjects with 1757 masses (1079 [61.4%] benign and 678 [38.6%] malignant masses), OA/US downgraded 40.8% (3078/7535) of benign mass reads, with a specificity of 43.0% (3242/7538, 99% confidence interval [CI]: 40.4%, 45.7%) for OA/US versus 28.1% (2120/7543, 99% CI: 25.8%, 30.5%) for the internal US of the OA/US device. OA/US exceeded US in specificity by 14.9% (P < .0001; 99% CI: 12.9, 16.9%). Sensitivity for biopsied malignant masses was 96.0% (4553/4745, 99% CI: 94.5%, 97.0%) for OA/US and 98.6% (4680/4746, 99% CI: 97.8%, 99.1%) for US (P < .0001). The negative likelihood ratio of 0.094 for OA/US indicates a negative examination can reduce a maximum US-assigned pretest probability of 17.8% (low BI-RADS 4B) to a posttest probability of 2% (BI-RADS 3). Conclusion OA/US increases the specificity of breast mass assessment compared with the device internal grayscale US alone. Online supplemental material is available for this article. © RSNA, 2017.

American College of Radiology-Compliant Short Protocol Breast MRI for High-Risk Breast Cancer Screening: A Prospective Feasibility Study.

OBJECTIVE: The purpose of this study was to assess the feasibility of a short protocol for screening breast MRI that is noninferior to standard-of-care (SOC) MRI in image quality that complies with American College of Radiology accreditation requirements. SUBJECTS AND METHODS: In a prospective feasibility trial, 23 women at high risk underwent both an initial SOC MRI examination that included axial iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) and T1-weighted volume imaging for breast assessment (VIBRANT) dynamic contrast-enhanced sequences and a separate short breast MRI protocol comprising a fast spin-echo (FSE) triple-echo Dixon T2 sequence for T2-weighted imaging and a 3D dual-echo fast spoiled gradient-echo two-point Dixon sequence for dynamic contrast-enhanced imaging from October 1, 2015, through May 2, 2016. Image quality assessment was performed by three radiologists, who scored the images for fat saturation, artifact severity, and quality of normal anatomic structures. Enhancing lesions were evaluated according to BI-RADS MRI features. Quantitative analysis was performed by measuring the signal intensity of anatomic areas in each patient. RESULTS: The mean acquisition time for short-protocol breast MRI was 9.42 minutes and for SOC MRI was 22.09 minutes (p < 0.0001). The mean table times were 13.92 and 35.87 minutes (p < 0.0001). Compared with the FSE triple-echo Dixon T2 short-protocol breast MRI sequence, the IDEAL SOC MRI sequence had significantly worse motion artifact (p < 0.01) and fat saturation (p = 0.04). The other parameters did not differ significantly. Quantitative analysis showed that the FSE triple-echo Dixon T2 sequence had more effective fat saturation and higher tissue contrast. All five lesions were given the same assessments by the readers, and at BI-RADS lesion morphologic ranking, identical high image quality scores were assigned to both the VIBRANT and 3D dual-echo fast spoiled gradient-echo 2-point Dixon sequences. CONCLUSION: Short-protocol breast MRI comprising a T2-weighted sequence and a fast dynamic sequence with less than 10-minute acquisition time is feasible and has image quality at least equivalent to that of an SOC MRI protocol with a > 20-minute mean acquisition time. Larger studies comparing the cancer detection rate, sensitivity, and specificity of each imaging protocol are needed to determine whether short-protocol breast MRI can replace SOC MRI to screen patients at high breast cancer risk.

Optoacoustic Breast Imaging: Imaging-Pathology Correlation of Optoacoustic Features in Benign and Malignant Breast Masses.

OBJECTIVE: Optoacoustic ultrasound breast imaging is a fused anatomic and functional modality that shows morphologic features, as well as hemoglobin amount and relative oxygenation within and around breast masses. The purpose of this study is to investigate the positive predictive value (PPV) of optoacoustic ultrasound features in benign and malignant masses. SUBJECTS AND METHODS: In this study, 92 masses assessed as BI-RADS category 3, 4, or 5 in 94 subjects were imaged with optoacoustic ultrasound. Each mass was scored by seven blinded independent readers according to three internal features in the tumor interior and two external features in its boundary zone and periphery. Mean and median optoacoustic ultrasound scores were compared with histologic findings for biopsied masses and nonbiopsied BI-RADS category 3 masses, which were considered benign if they were stable at 12-month follow-up. Statistical significance was analyzed using a two-sided Wilcoxon rank sum test with a 0.05 significance level. RESULTS: Mean and median optoacoustic ultrasound scores for all individual internal and external features, as well as summed scores, were higher for malignant masses than for benign masses (p < 0.0001). High external scores, indicating increased hemoglobin and deoxygenation and abnormal vessel morphologic features in the tumor boundary zone and periphery, better distinguished benign from malignant masses than did high internal scores reflecting increased hemoglobin and deoxygenation within the tumor interior. CONCLUSION: High optoacoustic ultrasound scores, particularly those based on external features in the boundary zone and periphery of breast masses, have high PPVs for malignancy and, conversely, low optoacoustic ultrasound scores have low PPV for malignancy. The functional component of optoacoustic ultrasound may help to overcome some of the limitations of morphologic overlap in the distinction of benign and malignant masses.

Downgrading and Upgrading Gray-Scale Ultrasound BI-RADS Categories of Benign and Malignant Masses With Optoacoustics: A Pilot Study.

OBJECTIVE: False-positive findings remain challenging in breast imaging. This study investigates the incremental value of optoacoustic imaging in improving BI-RADS categorization of breast masses at ultrasound. SUBJECTS AND METHODS: The study device is an optoacoustic breast imaging device with a handheld duplex laser and internal gray-scale ultrasound probe, fusing functional and morphologic information (optoacoustic ultrasound). In this prospective multisite study, breast masses assessed as BI-RADS category 3, 4A, 4B, 4C, or 5 by site radiologists underwent both gray-scale ultrasound and optoacoustic imaging with the study device. Independent reader radiologists assessed internal gray-scale ultrasound and optoacoustic ultrasound features for each mass and assigned a BI-RADS category. The percentage of mass reads for which optoacoustic ultrasound resulted in a downgrade or upgrade of BI-RADS category relative to internal gray-scale ultrasound was determined. RESULTS: Of 94 total masses, 39 were biopsy-proven malignant, 44 were biopsy-proven benign, and 11 BI-RADS category 3 masses were stable at 12-month follow-up. The sensitivity of both optoacoustic ultrasound and internal gray-scale ultrasound was 97.1%. The specificity was 44.3% for optoacoustic ultrasound and 36.4% for internal gray-scale ultrasound. Using optoacoustic ultrasound, 41.7% of benign masses or BI-RADS category 3 masses that were stable at 12-month follow-up were downgraded to BI-RADS category 2 by independent readers; 36.6% of masses assigned BI-RADS category 4A were downgraded to BI-RADS category 3 or 2, and 10.1% assigned BI-RADS category 4B were downgraded to BI-RADS category 3 or 2. Using optoacoustic ultrasound, independent readers upgraded 75.0% of the malignant masses classified as category 4A, 4B, 4C, or 5, and 49.4% of the malignant masses were classified as category 4B, 4C, or 5. CONCLUSION: Optoacoustic ultrasound resulted in BI-RADS category downgrading of benign masses and upgrading of malignant masses compared with gray-scale ultrasound.

Imaging-Concordant Benign MRI-Guided Vacuum-Assisted Breast Biopsy May Not Warrant MRI Follow-Up.

OBJECTIVE: The follow-up of breast lesions with imaging-concordant benign histopathology results on MRI-guided vacuum-assisted biopsy (VAB) is not currently standardized. We determined the false omission rate of breast MRI-guided VAB with benign histopathology (negative results) to assess whether breast MRI follow-up is needed. MATERIALS AND METHODS: The medical records of patients who underwent 9-gauge breast MRI-guided VAB during 2007-2012 were reviewed retrospectively. Lesions with imaging-concordant benign histopathology results from MRI-guided VAB and surgery or 2 years or more of imaging follow-up were included. The false omission rate (1 - negative predictive value; [number of false-negative results / number of negative results]) of MRI-guided VAB was calculated. RESULTS: One hundred sixty-nine lesions were included, and 135 had only imaging follow-up (mammography follow-up: range, 17-107 months [median, 52 months]; MRI follow-up: range, 5-95 months [median, 35 months]). Of the 135 lesions with only imaging follow-up, 48 had mammography only (range, 26-86 months; median, 52 months), and 87 had mammography (range, 17-107 months; median, 52 months) and MRI (range, 5-95 months; median, 35 months). Thirty-four lesions had surgical correlation, and there were no cases of imaging-surgical discordance. Four malignancies were later diagnosed in the same breast in which MRI-guided VAB had been performed. One (0.6%) malignancy was invasive ductal carcinoma at 1 cm from the MRI-guided VAB site; it was mammographically detected 24 months after MRI-guided VAB. The other three malignancies developed 4 cm or more from the site of MRI-guided VAB: one ductal carcinoma in situ (DCIS) detected on mammography 12 months after MRI-guided VAB, one DCIS detected on MRI 24 months after MRI-guided VAB, and one Paget disease lesion detected at physical examination 32 months after MRI-guided VAB. CONCLUSION: Breast MRI-guided VAB has a low false omission rate. MRI follow-up of lesions with concordant benign MRI-guided VAB histopathology results may not be warranted.

Imaging Factors That Influence Surgical Margins After Preoperative 125I Radioactive Seed Localization of Breast Lesions: Comparison With Wire Localization.

OBJECTIVE: The objective of this study was to compare the potential influence of imaging variables on surgical margins after preoperative radioactive seed localization (RSL) and wire localization (WL) techniques. MATERIALS AND METHODS: A total of 565 women with 660 breast lesions underwent RSL or WL between May 16, 2012, and May 30, 2013. Patient age, lesion type (mass, calcifications, mass with associated calcifications, other), lesion size, number of seeds or wires used, surgical margin status (close positive or negative margins), and reexcision and mastectomy rates were recorded. RESULTS: Of 660 lesions, 127 (19%) underwent RSL and 533 (81%) underwent WL preoperatively. Mean lesion size was 1.8 cm in the RSL group and 1.8 cm in the WL group (p = 0.35). No difference in lesion type was identified in the RSL and WL groups (p = 0.63). RSL with a single seed was used in 105 of 127 (83%) RSLs compared with WL with a single wire in 349 of 533 (65%) WLs (p = 0.0003). The number of cases with a close positive margin was similar for RSLs (26/127, 20%) and WLs (104/533, 20%) (p = 0.81). There was no difference between the RSL group and the WL group in close positive margin status (20% each, p = 0.81), reexcision rates (20% vs 16%, respectively; p = 0.36), or mastectomy rates (6% each, p = 0.96). Lesions containing calcifications were more likely to require more than one wire (odds ratio [OR], 4.44; 95% CI, 2.8-7.0) or more than one seed (OR, 7.03; 95% CI, 1.6-30.0) when compared with masses alone (p < 0.0001). Increasing lesion size and the presence of calcifications were significant predictors of positive margins, whereas the use of more than one wire or seed was not (OR, 0.9; 95% CI, 0.5-1.5) (p = 0.75). CONCLUSION: Close positive margin, reexcision, and mastectomy rates remained similar in the WL group and RSL group. The presence of calcifications and increasing lesion size increased the odds of a close positive margin in both the WL and RSL groups, whereas the use of one versus more than one seed or wire did not.