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 healthcare costs. Purpose: To evaluate the cost-effectiveness of a strategy of ultrasound first versus of 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. healthcare 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. Each strategy's total cost and effectiveness [in quality-adjusted life years (QALY)] were estimated. Cost-effectiveness was assessed through incremental cost-effectiveness ratios (ICER) and incremental net monetary benefit, using a willingness-to-pay (WTP) threshold of $100,000 per QALY gained. Deterministic sensitivity analyses were performed to estimate the impact of different input parameters; probabilistic sensitivity analysis with Monte Carlo simulations was performed 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 ultrasound first, versus a strategy of diagnostic mammography first, was more cost-saving (total cost of $17,672 vs $18,323) and more effective (QALYs of 23.1309 vs 23.1306), over the 40-year horizon. Ultrasound first resulted in an ICER of +2,170,2000 and incremental net monetary benefit of $681 versus diagnostic mammography first. Therefore, 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 the lost utility from delayed diagnosis, followed by 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 ultrasound first, with or without diagnostic mammography, is more cost effective compared to a traditional strategy of diagnostic mammography first. Clinical Impact: This cost-effectiveness analysis supports 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.

Imaging Challenges in Diagnosing Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) refers to a heterogeneous group of carcinomas that have more aggressive biologic features, faster growth, and a propensity for early distant metastasis and recurrence compared with other breast cancer subtypes. Due to the aggressiveness and rapid growth of TNBCs, there are specific imaging challenges associated with their timely and accurate diagnosis. TNBCs commonly manifest initially as circumscribed masses and therefore lack the typical features of a primary breast malignancy, such as irregular shape, spiculated margins, and desmoplastic reaction. Given the potential for misinterpretation, review of the multimodality imaging appearances of TNBCs is important for guiding the radiologist in distinguishing TNBCs from benign conditions. Rather than manifesting as a screening-detected cancer, TNBC typically appears clinically as a palpable area of concern that most commonly corresponds to a discrete mass at mammography, US, and MRI. The combination of circumscribed margins and hypoechoic to anechoic echogenicity may lead to TNBC being misinterpreted as a benign fibroadenoma or cyst. Therefore, careful mammographic and sonographic evaluation with US image optimization can help avoid misinterpretation. Radiologists should recognize the characteristics of TNBCs that can mimic benign entities, as well as the subtle features of TNBCs that should raise concern for malignancy and aid in timely and accurate diagnosis. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Imaging and Management of Fibroepithelial Lesions of the Breast: Radiologic-Pathologic Correlation.

Fibroepithelial lesions (FELs) are among the most common breast masses encountered by breast radiologists and pathologists. They encompass a spectrum of benign and malignant lesions, including fibroadenomas (FAs) and phyllodes tumors (PTs). FAs are typically seen in young premenopausal women, with a peak incidence at 20-30 years of age, and have imaging features of oval circumscribed hypoechoic masses. Although some FA variants are especially sensitive to hormonal influences and can exhibit rapid growth (eg, juvenile FA and lactational adenomas), most simple FAs are slow growing and involute after menopause. PTs can be benign, borderline, or malignant and are more common in older women aged 40-50 years. PTs usually manifest as enlarging palpable masses and are associated with a larger size and sometimes with an irregular shape at imaging compared with FAs. Although FA and FA variants are typically managed conservatively unless large and symptomatic, PTs are surgically excised because of the risk of undersampling at percutaneous biopsy and the malignant potential of borderline and malignant PTs. As a result of the overlap in imaging and histologic appearances, FELs can present a diagnostic challenge for the radiologist and pathologist. Radiologists can facilitate accurate diagnosis by supplying adequate tissue sampling and including critical information for the pathologist at the time of biopsy. Understanding the spectrum of FELs can facilitate and guide appropriate radiologic-pathologic correlation and timely diagnosis and management of PTs. Published under a CC BY 4.0 license. Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Radiologists' Increasing Role in Population Health Management: AJR Expert Panel Narrative Review.

Population health management (PHM) is the holistic process of improving health outcomes of groups of individuals through the support of appropriate financial and care models. Radiologists' presence at the intersection of many aspects of health care, including screening, diagnostic imaging, and image-guided therapies, provides the opportunity for increased radiologist engagement in PHM. Furthermore, innovations in artificial intelligence and imaging informatics will serve as critical tools to improve value in health care through evidence-based and equitable approaches. Given radiologists' limited engagement in PHM to date, it is imperative to define the PHM priorities of the specialty so that radiologists' full value in improving population health is realized. The purpose of this expert review is to explore programs and future directions for radiologists in PHM.

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.

Axillary Lymphadenopathy in the COVID-19 Era: What the Radiologist Needs to Know.

Axillary lymphadenopathy caused by the high immunogenicity of messenger RNA (mRNA) COVID-19 vaccines presents radiologists with new diagnostic dilemmas in differentiating vaccine-related benign reactive lymphadenopathy from that due to malignant causes. Understanding axillary anatomy and lymphatic drainage is key to radiologic evaluation of the axilla. US plays a critical role in evaluation and classification of axillary lymph nodes on the basis of their cortical and hilar morphology, which allows prediction of metastatic disease. Guidelines for evaluation and management of axillary lymphadenopathy continue to evolve as radiologists gain more experience with axillary lymphadenopathy related to COVID-19 vaccines. General guidelines recommend documenting vaccination dates and laterality and administering all vaccine doses contralateral to the site of primary malignancy whenever applicable. Guidelines also recommend against postponing imaging for urgent clinical indications or for treatment planning in patients with newly diagnosed breast cancer. Although conservative management approaches to axillary lymphadenopathy initially recommended universal short-interval imaging follow-up, updates to those approaches as well as risk-stratified approaches recommend interpreting lymphadenopathy in the context of both vaccination timing and the patient's overall risk of metastatic disease. Patients with active breast cancer in the pretreatment or peritreatment phase should be evaluated with standard imaging protocols regardless of vaccination status. Tissue sampling and multidisciplinary discussion remain useful in management of complex cases, including increasing lymphadenopathy at follow-up imaging, MRI evaluation of extent of disease, response to neoadjuvant treatment, and potentially confounding cases. An invited commentary by Weinstein is available online. ©RSNA, 2022.

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.

Diagnosis, Management, and Percutaneous Sampling of Nipple-Areolar Calcifications: How Radiologists Can Help Patients Avoid the Operating Room.

OBJECTIVE: Both benign and malignant causes of calcifications in the nipple-areolar complex exist. BI-RADS terminology applies to the description and classification of nipple-areolar calcifications in the same way it does to calcifications elsewhere in the breast. Minimally invasive sampling can be performed safely and accurately with ultrasound-guided techniques, with a few technical modifications. CONCLUSION: This article provides insight regarding the management algorithm and image-guided interventional techniques for sampling nipple-areolar calcifications as an essential competency for breast imaging practices.

Breast density, MR imaging biomarkers, and breast cancer risk.

Mammographic breast density and various breast MRI features are imaging biomarkers that can predict a woman's future risk of breast cancer. While mammographic density (MD) has been established as an independent risk factor for the development of breast cancer, MD assessment methods need to be accurate and reproducible for widespread clinical use in stratifying patients based on their risk. In addition, a number of breast MRI biomarkers using contrast-enhanced and noncontrast-enhanced techniques are also being investigated as risk predictors. The validation and standardization of these breast MRI biomarkers will be necessary for population-based clinical implementation of patient risk stratification, as well. This review provides an update on MD assessment methods, breast MRI biomarkers, and their ability to predict breast cancer risk.

Diagnostic evaluation and treatment of primary breast osteosarcoma: A case report.

Primary breast osteosarcoma (PBO) is a rare tumor of the breast, with only case reports and small case series published in the literature. Classic imaging findings of sunburst calcifications, a rim of intermediate density, and intense uptake on bone scintigraphy can help make the correct diagnosis preoperatively, allowing for appropriate surgical and chemotherapeutic management. We present the imaging evaluation, treatment course, and follow-up of a case of PBO diagnosed in a 67-year-old patient.

Breast ultrasound utilization in a safety net emergency department.

PURPOSE: The purpose of this study is to (1) assess the diagnostic yield of ultrasounds performed in the emergency department for suspected breast abscess and determine the rates of reimaging, discordance, and emergent intervention in a large, busy safety net hospital and (2) determine clinical factors significantly associated with abscess as a way to improve patient selection for emergent breast ultrasounds. METHODS: A total of 581 consecutive breast ultrasounds performed in the emergency department for suspected abscess over 15 months were retrospectively reviewed for imaging, demographics, laboratory data, and physical exam findings. Breast abscess was confirmed by combining imaging, clinical, and laboratory data. Linear logistic regression analysis estimated the likelihood of abscess, and the cross-validated area under the receiver operating characteristic curve (AUC) evaluated diagnostic performance. RESULTS: Final diagnoses included abscess (153/581, 26%), cancer (29/581, 5%), granulomatous mastitis (41/581, 7%), normal (120/581, 21%), and other/indeterminate (238/581, 41%). Factors associated with abscess included induration, fluctuance, erythema, drainage, smoking, diabetes, and Black race. Based on these factors, the AUC of the characteristics predictive of abscess was 0.77 (CI, 0.72-0.81). Six breast cancers were not diagnosed on ultrasound. 40% of ultrasounds (231/581) were considered incomplete/inadequate. CONCLUSION: 74% (428/581) of emergent breast ultrasounds in our population were negative for abscess, while 21% (6/29) of cancers were not diagnosed, and 40% (231/581) of exams were incomplete/inadequate. Patient selection for emergent ultrasounds can be improved, allowing patients with a low likelihood of abscess to be imaged in a more optimal setting.

Mammographic density changes in surgical weight loss-an indication for personalized screening.

BACKGROUND: Obesity and high radiologic breast density independently increase breast cancer risk. We evaluated the effect of surgical weight loss on mammographic density (MD). METHODS: Patients undergoing bariatric surgery and screening mammography (MG) were identified, data regarding demographics, comorbidities, calculated and genetic breast cancer risk was collected. Patients had a MG before and after surgery. Fellowship-trained breast radiologists assigned Breast Imaging Reporting and Data System density categories. RESULTS: Patients underwent sleeve gastrectomy (n = 56) or gastric bypass (n = 7), 78% had hypertension, 48% had diabetes. Four had deleterious BRCA mutations, four were calculated high risk. Mean weight loss = 28.7 kg. Mean initial BMI = 44.3 kg/m2 (range:33-77), final BMI = 33.6 kg/m2 (range:20-62;p < 0.01). Density was unchanged in 53, decreased in 1, increased in 9. Of these 9(14%), 5 changed from almost entirely fatty to scattered MD, and 4 changed from scattered MD to heterogeneously dense. Mean weight loss of the 9 with increased MD was greater than the cohort (37.7vs.28.7 kg;p < 0.01). CONCLUSIONS: Surgical weight loss increased MD in 14%. Increased MD masks malignancies, patients may benefit from additional screening based on calculated risk assessments that include MD.

Bracketed radioactive seed localization vs bracketed wire-localization in breast surgery.

Multiple localizers placed in a bracketed fashion facilitates excision of radiographically extensive breast lesions. In this study, bracketed radioactive seed localization (bRSL) was compared to bracketed wire localization (bWL). We hypothesized that bRSL would achieve adequate margins and decrease re-operation rates with similar or less specimen volumes (SV) than bWL. Retrospective review identified patients who underwent bracketed breast procedures at an academic medical center. Data collected included patient demographics, tumor features, treatment variables, and surgical outcomes. Wilcoxon rank-sum test and chi-square test were used to compare continuous and categorical data, respectively. A multivariable logistic regression model was used to evaluate the association between re-excision and localization technique after adjusting for clinically relevant variables. Patients who underwent bWL were 3.9 times more likely to undergo re-excision compared to patients in bRSL group (OR=3.9, 95% CI: 2.0-7.4). Initial and total SV did not significantly differ between the two groups (P=.4). Patients were significantly more likely to undergo a mastectomy in the bWL group than in the bRSL group (24% vs 7%; P<.01). For patients undergoing excision of radiologically extensive breast lesions, bRSL serves as an alternative to bWL. In this retrospective study, bRSL was associated with a decreased re-excision rate with similar SV and a lower rate of mastectomy when compared to bWL.

Positive Effect of a Financial Incentive on Radiologist Compliance With Quality Metric Placement in Knee Radiography Reports.

PURPOSE: Ongoing quality improvement (QI) processes in the authors' department include the insertion of a Kellgren-Lawrence (KL) osteoarthritis grading template in knee radiography reports to decrease unnecessary MRI. However, uniform adoption of this grading system is lacking. Department-wide financial incentives were instituted to improve compliance with QI metrics. The purpose of this study was to evaluate the effect of a financial incentive on KL grading system use and to compare compliance rates of musculoskeletal (MSK) radiologists with those of general radiologists who were not financially incentivized to use KL grading. METHODS: Percentages of all knee radiography reports containing KL grading with standardized follow-up recommendations were determined by querying the departmental radiology database before and after the introduction of the new quality-based financial incentive. Preincentive compliance rates for MSK and general radiologists were compared with an adoption period and two separate 6-month postincentive periods. RESULTS: In total, 52,673 reports were retrospectively analyzed for KL grading use (41,670 reports interpreted by MSK radiologists and 11,003 interpreted by general radiologists). Increase in compliance was greatest among MSK radiologists' reports during the incentivized adoption period (from 36.1% to 53.2%). This improvement was sustained among MSK radiologists and averaged 62.7% during the most recently studied postimplementation period. A lesser degree of improvement in compliance was observed in nonincentivized general radiologists' reports (from 19.3% to 27.5%); during the postimplementation follow-up period, their compliance decreased to 26.5%. CONCLUSIONS: The introduction of a financial incentive resulted in significantly increased adoption of QI practices with sustained improvement among incentivized MSK radiologists compared with nonincentivized general radiologists.

Next Level of Care Protocols in Radiology: Improving Patient Access to Care.

OBJECTIVE: To introduce a novel next level of care (NLC) protocol used in our breast imaging practice to bypass additional imaging and image-guided biopsy orders and to examine the impact of NLC on breast biopsy wait times compared with thyroid biopsy wait times, which do not use NLC. METHODS: Our institutional review board deemed this retrospective analysis to be exempt. NLC was implemented for breast imaging in late 2014. Two 6-month periods before and after the COVID-19 shutdown were sampled and compiled. Data were queried from departmental database and electronic health record for all breast and thyroid biopsies during this time. Time to biopsy (TTB) was defined as the number of days from the diagnostic imaging evaluation recommending the biopsy to the completion of the biopsy. To determine the effect of NLC, TTB was compared between breast and thyroid biopsies. RESULTS: Of the 1,114 breast biopsies and 154 thyroid biopsies included, the mean TTB was 9 days (95% confidence interval 8.4-9.3) for breast and 23 days (95% confidence interval 20.5-25.0) for thyroid. There was a 61% reduction in the mean TTB for patients in the breast group compared with patients in the thyroid group. The effect of the NLC was comparable among different races and ethnicities in the breast group, but a significantly higher mean TTB (24% higher, P = .025) was observed for thyroid biopsies in Black patients compared with thyroid biopsies in Hispanic patients. CONCLUSION: NLC protocol facilitates imaging evaluations and reduces the time interval to image-guided biopsies.

Imaging of COVID-19 Vaccine-Related Axillary Lymphadenopathy: Initial Outcomes Based on US Features of Axillary Lymph Nodes.

OBJECTIVE: The purpose of this study is to describe the imaging characteristics and outcomes of COVID-19 vaccine-related axillary adenopathy and subsequent follow-up. METHODS: This was an IRB-approved, retrospective study of patients with imaging evidence of axillary lymphadenopathy who had received at least one dose of a COVID-19 vaccine and presented between January 1, 2021, and February 28, 2021. Sonographic cortical thickness and morphology was evaluated. A mixed effects model was used to model lymph node cortical thickness decrease over time. RESULTS: A total of 57 women were identified with lymphadenopathy and a COVID vaccination during the study period with 51 (89.5%) women completing imaging surveillance or undergoing tissue sampling of a lymph node. Three women (5.9%) were diagnosed with metastatic breast cancer to an axillary node. There was a statistically significant correlation with cortical thickness at initial US evaluation and malignancy (7.7 mm [SD ±â€…0.6 mm] for metastatic nodes and 5 mm [SD ±â€…2 mm] for benign nodes, P = 0.02). Suspicious morphological features (effacement of fatty hilum, P = 0.02) also correlated with malignancy. Time to resolution of lymphadenopathy can be prolonged with estimated half-life of the rate of decrease in cortical thickness modeled at 77 days (95% CI, 59-112 days). Diffuse, smooth cortical thickening over 3 mm was the most common lymph node morphology. CONCLUSION: Malignant lymph node morphology and cortical thickness best predicted malignancy. Benign hyperplastic lymph nodes were the most common morphology observed after COVID-19 vaccination. Lymphadenopathy after vaccination is slow to resolve.