Building Radiology Equity: Themes from the 2023 RAD-AID Conference on International Radiology and Global Health.

Low- and middle-income countries are significantly impacted by the global scarcity of medical imaging services. Medical imaging is an essential component for diagnosis and guided treatment, which is needed to meet the current challenges of increasing chronic diseases and preparedness for acute-care response. We present some key themes essential for improving global health equity, which were discussed at the 2023 RAD-AID Conference on International Radiology and Global Health. They include (1) capacity building, (2) artificial intelligence, (3) community-based patient navigation, (4) organizational design for multidisciplinary global health strategy, (5) implementation science, and (6) innovation. Although not exhaustive, these themes should be considered influential as we guide and expand global health radiology programs in low- and middle-income countries in the coming years.

PACS-integrated machine learning breast density classifier: clinical validation.

OBJECTIVE: To test the performance of a novel machine learning-based breast density tool. The tool utilizes a convolutional neural network to predict the BI-RADS based density assessment of a study. The clinical density assessments of 33,000 mammographic examinations (164,000 images) from one academic medical center (Site A) were used for training. MATERIALS AND METHODS: This was an IRB approved HIPAA compliant study performed at two academic medical centers. The validation data set was composed of 500 studies from one site (Site A) and 700 from another (Site B). At Site A, each study was assessed by three breast radiologists and the majority (consensus) assessment was used as truth. At Site B, if the tool agreed with the clinical reading, then it was considered to have correctly predicted the clinical reading. In cases where the tool and the clinical reading disagreed, then the study was evaluated by three radiologists and the consensus reading was used as the clinical reading. RESULTS: For the classification into the four categories of the Breast Imaging Reporting and Data System (BI-RADS®), the AI classifier had an accuracy of 84.6% at Site A and 89.7% at Site B. For binary classification (dense vs. non-dense), the AI classifier had an accuracy of 94.4% at Site A and 97.4% at Site B. In no case did the classifier disagree with the consensus reading by more than one category. CONCLUSIONS: The automated breast density tool showed high agreement with radiologists' assessments of breast density.

False-Negative Rates of Breast Cancer Screening with and without Digital Breast Tomosynthesis.

Background Screening with digital breast tomosynthesis (DBT) improves breast cancer detection and recall rates compared with those obtained with digital mammography (DM); however, the impact of DBT on patient survival has not been established. False-negative (FN) screening examinations can be a surrogate for long-term outcomes, such as breast cancer morbidity and mortality. Purpose To determine if screening with DBT is associated with lower FN rates, detection of cancers with more favorable prognoses, and improved performance outcomes versus DM. Materials and Methods This retrospective study involved 10 academic and community practices. DM screening examinations 1 year prior to DBT implementation and DBT screening examinations from the start date until June 30, 2013, were linked to cancers through June 30, 2014, with data collection in 2016 and analysis in 2018-2019. Cancers after FN examinations were characterized by presentation, either symptomatic or asymptomatic. FN rates, sensitivity, specificity, cancer detection and recall rates, positive predictive values, tumor size, histologic features, and receptor profile were compared. Results A total of 380 641 screening examinations were included. There were 183 989 DBT and 196 652 DM examinations. With DBT, rates trended lower for overall FN examinations (DBT, 0.6 per 1000 screens; DM, 0.7 per 1000 screens; P = .20) and symptomatic FN examinations (DBT, 0.4 per 1000 screens; DM, 0.5 per 1000 screens; P = .21). Asymptomatic FN rates trended higher in women with dense breasts (DBT, 0.14 per 1000 screens; DM: 0.07 per 1000 screens; P = .07). With DBT, improved sensitivity (DBT, 89.8% [966 of 1076 cancers]; DM, 85.6% [789 of 922 cancers]; P = .004) and specificity (DBT, 90.7% [165 830 of 182 913 examinations]; DM, 89.1% [174 480 of 195 730 examinations]; P < .001) were observed. Overall, cancers identified with DBT were more frequently invasive (P < .001), had fewer positive lymph nodes (P = .04) and distant metastases (P = .01), and had lower odds of an FN finding of advanced cancer (odds ratio, 0.9 [95% CI: 0.5, 1.5]). Conclusion Screening with digital breast tomosynthesis improves sensitivity and specificity and reveals more invasive cancers with fewer nodal or distant metastases. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Schattner in this issue.

Synthesized Mammography: Clinical Evidence, Appearance, and Implementation.

Digital breast tomosynthesis (DBT) has improved conventional mammography by increasing cancer detection while reducing recall rates. However, these benefits come at the cost of increased radiation dose. Synthesized mammography (s2D) has been developed to provide the advantages of DBT with nearly half the radiation dose. Since its F.D.A. approval, multiple studies have evaluated the clinical performance of s2D. In clinical practice, s2D images are not identical to conventional 2D images and are designed for interpretation with DBT as a complement. This article reviews the present literature to assess whether s2D is a practical alternative to conventional 2D, addresses the differences in mammographic appearance of findings, and provides suggestions for implementation into clinical practice.

Retroareolar masses and intraductal abnormalities detected on screening ultrasound: can biopsy be avoided?

To investigate the malignancy rate of retroareolar masses and intraductal abnormalities discovered in asymptomatic females during screening whole breast ultrasound (US-S) and determine if biopsy can be avoided. METHODS:: This is a HIPAA compliant retrospective study. Our radiology electronic medical records were searched for the phrases "retroareolar mass" or "intraductal mass" combined with "screening whole breast ultrasound" performed between 10/1/2009 and 5/30/2015. Inclusion criteria included retroareolar masses in asymptomatic females with normal mammography, mammographically dense breast tissue and imaging or biopsy follow-up. RESULTS:: 1136 charts were reviewed. 87 BI-RADS 3 and 4 retroareolar findings were included in final analysis. The average lesion size was 9.5 mm (range 4-28 mm). 47/87 lesions were classified as BI-RADS 3 and 40/87 BI-RADS 4. Of the 47 BI-RADS 3 lesions, 36 were stable on follow-up; 6 benign lesions were biopsied at patients' request; and 5 biopsied due to suspicious interval change on follow-up imaging, including 4 benign lesions and a 5 mm Grade 2 ductal carcinoma in situ . 3/40 BI-RADS 4 lesions were not biopsied and stable at follow-up; 37/40 lesions underwent benign biopsy. The malignancy rate of BI-RADS 3 and 4 lesions was 2.1% [CI (0.4-11.1)] and 0% [CI (0.0-8.8)], respectively. The overall combined malignancy rate was 1/87 [1.1%, CI (0.2-6.2)]. CONCLUSION:: The malignancy rate for BI-RADS 3 and 4 retroareolar masses and intraductal abnormalities detected on US-S is low (<2%). ADVANCES IN KNOWLEDGE:: Careful imaging surveillance in lieu of biopsy of these lesions may be appropriate in asymptomatic females with negative mammography.

Effect of age on breast cancer screening using tomosynthesis in combination with digital mammography.

PURPOSE: To determine the effect of tomosynthesis imaging as a function of age for breast cancer screening. METHODS: Screening performance metrics from 13 institutions were examined for 12 months prior to introduction of tomosynthesis (period 1) and compared to those after introduction of tomosynthesis (period 2, range 3-22 months). Screening metrics for women ages 40-49, 50-59, 60-69, and 70+ , included rates per 1000 screens for recalls, biopsies, cancers, and invasive cancers detected. RESULTS: Performance parameters were compared for women screened with digital mammography alone (n = 278,908) and digital mammography + tomosynthesis (n = 173,414). Addition of tomosynthesis to digital mammography produced significant reductions in recall rates for all age groups and significant increases in cancer detection rates for women 40-69. Largest recall rate reduction with tomosynthesis was for women 40-49, decreasing from 137 (95% CI 117-156) to 115 (95% CI 95-135); difference, -22 (95% CI -26 to -18; P < .001). Simultaneous increase in invasive cancer detection rate for women 40-49 from 1.6 (95% CI 1.2-1.9) to 2.7 (95% CI 2.2-3.1) with tomosynthesis (difference, 1.1; 95% CI 0.6-1.6; P < .001) was observed. CONCLUSIONS: Addition of tomosynthesis to digital mammography increased invasive cancer detection rates for women 40-69 and decreased recall rates for all age groups with largest performance gains seen in women 40-49. The similar performance seen with tomosynthesis screening for women in their 40s compared to digital mammography for women in their 50s argues strongly for commencement of mammography screening at age 40 using tomosynthesis.

Implementation of Whole-Breast Screening Ultrasonography.

Whole-breast screening ultrasonography is being increasingly implemented in breast imaging centers because numerous studies have shown the benefit of supplemental screening for women with dense breasts and breast density notification laws are becoming more widespread. This article reviews the numerous considerations involved in integrating a screening ultrasonography program into a busy practice.

Advances in Digital Breast Tomosynthesis.

OBJECTIVE: Digital breast tomosynthesis (DBT) has rapidly emerged as an important new imaging tool that reduces the masking effect of overlapping fibroglandular tissue, thereby improving breast cancer detection. This article will review key features of DBT including technique, clinical implementation, and benign and malignant imaging findings. We will also present the benefits of DBT in screening, diagnostic workup, and image-guided biopsy. CONCLUSION: Tomosynthesis improves interpretive performance and will likely replace conventional 2D mammography in clinical practice.

In Vivo Changes of Breast Perfusion After Augmentation.

BACKGROUND: Revision surgeries after breast augmentation are associated with an increased risk of complications (eg, nipple areolar complex [NAC]) necrosis. Consequently, maintaining perfusion to the NAC is a critical aspect of secondary breast surgery. OBJECTIVES: The purpose of this study was to examine in vivo changes in perfusion to the NAC after implant breast augmentation using magnetic resonance imaging (MRI) technology. METHODS: High-resolution 3 Tesla MRI images of 10 women (20 breasts) with previous breast augmentation were compared to a control population of 15 women (30 breasts). Perforators from the internal mammary artery and lateral thoracic artery were examined for the diameter of the originating perforator, distance between the nipple and most distally visualized point of the medial and lateral perforator, and dominance pattern between the medial vs lateral perforators. RESULTS: No difference was found in the caliber of the medial vessels in the implant group compared to the control group. In contrast, the caliber of the lateral blood vessels trended towards being 20% larger in diameter in the augmented breasts. The distances between the nipple and the medial and lateral vessels increased. The frequencies in the distribution of dominance were not significantly different between the implant group and the control group. CONCLUSIONS: Overall, medial and lateral blood supply to the NAC are preserved in the augmented patient. Our results suggest a slight delay effect that seems to increase the caliber of the lateral perforators. In addition, the tissue expansion provided by the implants effectively increases the length of both perforators. LEVEL OF EVIDENCE: 3 Therapeutic.

Tomosynthesis in the Diagnostic Setting: Changing Rates of BI-RADS Final Assessment over Time.

Purpose To evaluate the effect of tomosynthesis in diagnostic mammography on the Breast Imaging Reporting and Data System (BI-RADS) final assessment categories over time. Materials and Methods This retrospective study was approved by the institutional review board. The authors reviewed all diagnostic mammograms obtained during a 12-month interval before (two-dimensional [2D] mammography [June 2, 2010, to June 1, 2011]) and for 3 consecutive years after (tomosynthesis year 1 [2012], tomosynthesis year 2 [2013], and tomosynthesis year 3 [2014]) the implementation of tomosynthesis. The requirement to obtain informed consent was waived. The rates of BI-RADS final assessment categories 1-5 were compared between the 2D and tomosynthesis groups. The positive predictive values after biopsy (PPV3) for BI-RADS category 4 and 5 cases were compared. The mammographic features (masses, architectural distortions, calcifications, focal asymmetries) of lesions categorized as probably benign (BI-RADS category 3) and those for which biopsy was recommended (BI-RADS category 4 or 5) were reviewed. The χ(2) test was used to compare the rates of BI-RADS final assessment categories 1-5 between the two groups, and multivariate logistic regression analysis was performed to compare all diagnostic studies categorized as BI-RADS 3-5. Results There was an increase in the percentage of cases reported as negative or benign (BI-RADS category 1 or 2) with tomosynthesis (58.7% with 2D mammography vs 75.8% with tomosynthesis at year 3, P < .0001). A reduction in the percentage of probably benign (BI-RADS category 3) final assessments also occurred (33.3% with 2D mammography vs 16.4% with tomosynthesis at year 3, P < .0001). Although the rates of BI-RADS 4 or 5 assessments did not change significantly with tomosynthesis (8.0% with 2D mammography vs 7.8% with tomosynthesis at year 3, P = .2), there was a significant increase in the PPV3 (29.6% vs 50%, respectively; P < .0001). These trends increased during the 3 years of tomosynthesis use. Conclusion Tomosynthesis in the diagnostic setting resulted in progressive shifts in the BI-RADS final assessment categories over time, with a significant increase in the proportion of studies classified as normal, a continued decrease in the rate of studies categorized as probably benign, and improved diagnostic confidence in biopsy recommendations. (©) RSNA, 2016.

Tomosynthesis-detected Architectural Distortion: Management Algorithm with Radiologic-Pathologic Correlation.

As use of digital breast tomosynthesis becomes increasingly widespread, new management challenges are inevitable because tomosynthesis may reveal suspicious lesions not visible at conventional two-dimensional (2D) full-field digital mammography. Architectural distortion is a mammographic finding associated with a high positive predictive value for malignancy. It is detected more frequently at tomosynthesis than at 2D digital mammography and may even be occult at conventional 2D imaging. Few studies have focused on tomosynthesis-detected architectural distortions to date, and optimal management of these distortions has yet to be well defined. Since implementing tomosynthesis at our institution in 2011, we have learned some practical ways to assess architectural distortion. Because distortions may be subtle, tomosynthesis localization tools plus improved visualization of adjacent landmarks are crucial elements in guiding mammographic identification of elusive distortions. These same tools can guide more focused ultrasonography (US) of the breast, which facilitates detection and permits US-guided tissue sampling. Some distortions may be sonographically occult, in which case magnetic resonance imaging may be a reasonable option, both to increase diagnostic confidence and to provide a means for image-guided biopsy. As an alternative, tomosynthesis-guided biopsy, conventional stereotactic biopsy (when possible), or tomosynthesis-guided needle localization may be used to achieve tissue diagnosis. Practical uses for tomosynthesis in evaluation of architectural distortion are highlighted, potential complications are identified, and a working algorithm for management of tomosynthesis-detected architectural distortion is proposed.

Early clinical experience with digital breast tomosynthesis for screening mammography.

PURPOSE: To examine recall rates from screening mammography and the mammographic findings that caused recall in women who underwent digital breast tomosynthesis with conventional mammography (referred to as two-dimensional [ 2D two-dimensional ] with three-dimensional [ 3D three-dimensional ] imaging [ 2D two-dimensional + 3D three-dimensional ]) and in women who underwent conventional mammography alone (referred to as 2D two-dimensional ). MATERIALS AND METHODS: This was an institutional review board-approved, HIPAA-compliant study with waivers of informed consent. A retrospective review of 2D two-dimensional + 3D three-dimensional and 2D two-dimensional screening mammograms from August 1, 2011, to December 31, 2012, was performed. Recall rates and abnormalities that caused recall were compared by controlling for differences in patient age, breast density, and risk factors. Cancer detection rate was assessed from this time period and from 1 year before the introduction of tomosynthesis for a historic control. RESULTS: This study included 17 955 screening mammograms; of the total, there were 8591 (47.8%) 2D two-dimensional + 3D three-dimensional screening examinations and 9364 (52.2%) 2D two-dimensional examinations. The recall rate was 7.8% (671 of 8592) for 2D two-dimensional + 3D three-dimensional and 12.3% (1154 of 9364) for 2D two-dimensional (P < .0001); the rate of recall was 36.6% lower in the 2D two-dimensional + 3D three-dimensional group than in the 2D two-dimensional group. Recall rates for the 2D two-dimensional + 3D three-dimensional group were significantly lower for patients with asymmetries, ( 2D two-dimensional + 3D three-dimensional vs 2D two-dimensional , 3.1% [267 of 8591] vs 7.4% [689 of 9364], respectively; P < .0001) and calcifications ( 2D two-dimensional + 3D three-dimensional vs 2D two-dimensional , 2.4% [205 of 8591] vs 3.2% [297 of 9364], respectively; P = .0014). For patients with masses and architectural distortion, the difference in recall rates was not significant (masses: 2D two-dimensional + 3D three-dimensional vs 2D two-dimensional , 2.5% [215 of 8591] vs 2.5% [237 of 9364], respectively; P = .90; architectural distortion: 2D two-dimensional + 3D three-dimensional vs 2D two-dimensional , 0.68% [58 of 8591] vs 0.69% [65 of 9364]; P = .88). Cancer detection was highest in the 2D two-dimensional + 3D three-dimensional group at 5.9 cancers per 1000 examinations, with 5.7 cancers per 1000 examinations in the concurrent 2D two-dimensional group, and 4.4 cancers per 1000 examinations in the historic control. CONCLUSION: Use of tomosynthesis ( 2D two-dimensional + 3D three-dimensional ) compared with conventional mammography ( 2D two-dimensional ) is associated with a lower recall rate of screening mammography, most often for asymmetries.

Breast cancer screening using tomosynthesis in combination with digital mammography.

IMPORTANCE: Mammography plays a key role in early breast cancer detection. Single-institution studies have shown that adding tomosynthesis to mammography increases cancer detection and reduces false-positive results. OBJECTIVE: To determine if mammography combined with tomosynthesis is associated with better performance of breast screening programs in the United States. DESIGN, SETTING, AND PARTICIPANTS: Retrospective analysis of screening performance metrics from 13 academic and nonacademic breast centers using mixed models adjusting for site as a random effect. EXPOSURES: Period 1: digital mammography screening examinations 1 year before tomosynthesis implementation (start dates ranged from March 2010 to October 2011 through the date of tomosynthesis implementation); period 2: digital mammography plus tomosynthesis examinations from initiation of tomosynthesis screening (March 2011 to October 2012) through December 31, 2012. MAIN OUTCOMES AND MEASURES: Recall rate for additional imaging, cancer detection rate, and positive predictive values for recall and for biopsy. RESULTS: A total of 454,850 examinations (n=281,187 digital mammography; n=173,663 digital mammography + tomosynthesis) were evaluated. With digital mammography, 29,726 patients were recalled and 5056 biopsies resulted in cancer diagnosis in 1207 patients (n=815 invasive; n=392 in situ). With digital mammography + tomosynthesis, 15,541 patients were recalled and 3285 biopsies resulted in cancer diagnosis in 950 patients (n=707 invasive; n=243 in situ). Model-adjusted rates per 1000 screens were as follows: for recall rate, 107 (95% CI, 89-124) with digital mammography vs 91 (95% CI, 73-108) with digital mammography + tomosynthesis; difference, -16 (95% CI, -18 to -14; P < .001); for biopsies, 18.1 (95% CI, 15.4-20.8) with digital mammography vs 19.3 (95% CI, 16.6-22.1) with digital mammography + tomosynthesis; difference, 1.3 (95% CI, 0.4-2.1; P = .004); for cancer detection, 4.2 (95% CI, 3.8-4.7) with digital mammography vs 5.4 (95% CI, 4.9-6.0) with digital mammography + tomosynthesis; difference, 1.2 (95% CI, 0.8-1.6; P < .001); and for invasive cancer detection, 2.9 (95% CI, 2.5-3.2) with digital mammography vs 4.1 (95% CI, 3.7-4.5) with digital mammography + tomosynthesis; difference, 1.2 (95% CI, 0.8-1.6; P < .001). The in situ cancer detection rate was 1.4 (95% CI, 1.2-1.6) per 1000 screens with both methods. Adding tomosynthesis was associated with an increase in the positive predictive value for recall from 4.3% to 6.4% (difference, 2.1%; 95% CI, 1.7%-2.5%; P < .001) and for biopsy from 24.2% to 29.2% (difference, 5.0%; 95% CI, 3.0%-7.0%; P < .001). CONCLUSIONS AND RELEVANCE: Addition of tomosynthesis to digital mammography was associated with a decrease in recall rate and an increase in cancer detection rate. Further studies are needed to assess the relationship to clinical outcomes.

Comparison of tomosynthesis plus digital mammography and digital mammography alone for breast cancer screening.

PURPOSE: To compare screening recall rates and cancer detection rates of tomosynthesis plus conventional digital mammography to those of conventional digital mammography alone. MATERIALS AND METHODS: All patients presenting for screening mammography between October 1, 2011, and September 30, 2012, at four clinical sites were reviewed in this HIPAA-compliant retrospective study, for which the institutional review board granted approval and waived the requirement for informed consent. Patients at sites with digital tomosynthesis were offered screening with digital mammography plus tomosynthesis. Patients at sites without tomosynthesis underwent conventional digital mammography. Recall rates were calculated and stratified according to breast density and patient age. Cancer detection rates were calculated and stratified according to the presence of a risk factor for breast cancer. The Fisher exact test was used to compare the two groups. Multivariate logistic regression was used to assess the effect of screening method, breast density, patient age, and cancer risk on the odds of recall from screening. RESULTS: A total of 13 158 patients presented for screening mammography; 6100 received tomosynthesis. The overall recall rate was 8.4% for patients in the tomosynthesis group and 12.0% for those in the conventional mammography group (P < .01). The addition of tomosynthesis reduced recall rates for all breast density and patient age groups, with significant differences (P < .05) found for scattered fibroglandular, heterogeneously dense, and extremely dense breasts and for patients younger than 40 years, those aged 40-49 years, those aged 50-59 years, and those aged 60-69 years. These findings persisted when multivariate logistic regression was used to control for differences in age, breast density, and elevated risk of breast cancer. The cancer detection rate was 5.7 per 1000 in patients receiving tomosynthesis versus 5.2 per 1000 in patients receiving conventional mammography alone (P = .70). CONCLUSION: Patients undergoing tomosynthesis plus digital mammography had significantly lower screening recall rates. The greatest reductions were for those younger than 50 years and those with dense breasts. A nonsignificant 9.5% increase in cancer detection was observed in the tomosynthesis group.