Financial Impact of Imaging Examination Site of Service in the Medicare Population.

PURPOSE: The financial sustainability of the US healthcare system is a growing concern in an environment of declining reimbursement and rising costs. Variable Centers for Medicare and Medicaid (CMS) reimbursement and denial rates for specific imaging examinations exist across sites of service, adding complexity to financial planning for healthcare organizations. Understanding the financial implications of site of service in existing CMS reimbursement for imaging may be of strategic importance for organizations going forward. MATERIALS AND METHODS: Current Procedural Terminology (CPT) codes were obtained for common cross-sectional imaging examinations using the 2022 CMS Medicare Physician Fee Schedule. Using reimbursement rates with historical volumes and denial rates, a simulation was created to estimate the overall reimbursement of paired hospital outpatient departments (HOPD) and free-standing office (FSO) sites. A baseline simulation was performed with random allocation of imaging examinations between sites of service, and an optimized simulation was performed to estimate the maximum financial impact of targeted allocation between sites. These simulations were performed for paired CT and MR scanners separately. RESULTS: For CT, the baseline simulation estimated annual average reimbursement for combined HOPD and FSO was $3.25M. Reimbursement increased to $3.51M after optimized reallocation of studies between sites of service, resulting in an expected gain of $260,162 for a set of paired HOPD and FSO scanners. For MR, the same approach resulted in baseline reimbursement of $2.51M, increasing to $2.60M upon reallocation between sites for an expected gain of $87,532. Assuming a stable cost of service delivery, this approach would result in improved margins of 8% for CT and 3.5% for MR. There were 28 CT and 19 MRI daily patient imaging appointments at each respective HOPD and FSO scanners, unchanged between baseline and optimized cases. Differences in reimbursement rates between sites were the dominant driver of increased margins at low denial rates, although denial rates became dominant at values greater than 50%. CONCLUSION: Given CMS payment and denial rate variability, optimally allocating imaging studies between sites of service may improve reimbursement for the same services delivered. Although financial incentives exist for site allocation, such decisions should require physician input to assess safety and appropriate level of care. This work contributes to an understanding of financial incentives of existing reimbursement policy and may guide future policy design towards high value care.

An Examination of Racial and Ethnic Disparities in the Use of Prostate Biopsy and Magnetic Resonance Imaging in Prostate Cancer Screening.

INTRODUCTION: We assessed racial and ethnic disparities in the use of prostate biopsy or MRI following an elevated PSA result. METHODS: We retrospectively evaluated insurance claims from Optum's de-identified Clinformatics Data Mart database from January 1, 2011 to December 31, 2017. This was a large commercially insured cohort from across the United States. We included all male enrollees over 40 years old receiving an elevated PSA result with no prior prostate biopsy or MRI and no confirmed urinary tract infection within 6 weeks of PSA test. RESULTS: A total of 765,409 participants met inclusion criteria with 43,711 (5.71%) receiving a PSA result above 4 ng/mL. Of these, 7,399 received either a prostate biopsy or MRI within 180 days. Men between ages 40-54 (29.48%) were most likely to receive prostate biopsy or MRI after an elevated PSA, followed by those between 55-64 (24.91%), 65-74 (18.56%), 75-84 (6.33%), and above 85 (3.62%). Compared to White patients, Black patients were more likely to receive either a prostate biopsy or MRI (OR: 1.16, 95% CI: 1.01, 1.32) following an elevated PSA level, while Asian (OR: 0.72, 95% CI: 0.54, 0.96) and Hispanic (OR: 0.83, 95% CI: 0.70, 0/97) patients were less likely. CONCLUSIONS: Physicians appear to be following the reported statistical incidence of prostate cancer by race and ethnicity when using prostate biopsy or MRI for patients with elevated PSA levels. These results demonstrate the importance of publishing statistical data on disease incidence by race and ethnicity for informing physicians' decision-making.

Comparison of Lung Cancer Screening Eligibility and Use between Commercial, Medicare, and Medicare Advantage Enrollees.

OBJECTIVE: Lung cancer screening does not require patient cost-sharing for insured people in the U.S. Little is known about whether other factors associated with patient selection into different insurance plans affect screening rates. We examined screening rates for enrollees in commercial, Medicare Fee-for-Service (FFS), and Medicare Advantage plans. METHODS: County-level smoking rates from the 2017 County Health Rankings were used to estimate the number of enrollees eligible for lung cancer screening in two large retrospective claims databases covering: a 5% national sample of Medicare FFS enrollees; and 100% sample of enrollees associated with large commercial and Medicare Advantage carriers. Screening rates were estimated using observed claims, stratified by payer, before aggregation into national estimates by payer and demographics. Chi-square tests were used to examine differences in screening rates between payers. RESULTS: There were 1,077,142 enrollees estimated to be eligible for screening. The overall estimated screening rate for enrollees by payer was 1.75% for commercial plans, 3.37% for Medicare FFS, and 4.56% for Medicare Advantage plans. Screening rates were estimated to be lowest among females (1.55%-4.02%), those aged 75-77 years (0.63%-2.87%), those residing in rural areas (1.88%-3.56%), and those in the West (1.16%-3.65%). Among Medicare FFS enrollees, screening rates by race/ethnicity were non-Hispanic White (3.71%), non-Hispanic Black (2.17%) and Other (1.68%). CONCLUSIONS: Considerable variation exists in lung cancer screening between different payers and across patient characteristics. Efforts targeting historically vulnerable populations could present opportunities to increase screening.

Patient Cost-Sharing and Utilization of Breast Cancer Diagnostic Imaging by Patients Undergoing Subsequent Testing After a Screening Mammogram.

Importance: Out-of-pocket costs (OOPCs) have been largely eliminated for screening mammography. However, patients still face OOPCs when undergoing subsequent diagnostic tests after the initial screening, which represents a potential barrier to those who require follow-up testing after initial testing. Objective: To examine the association between the degree of patient cost-sharing and the use of diagnostic breast cancer imaging after undergoing a screening mammogram. Design, Setting, and Participants: This retrospective cohort study used medical claims from Optum's deidentified Clinformatics Data Mart Database, a commercial claims database derived from a database of administrative health claims for members of large commercial and Medicare Advantage health plans. The large commercially insured cohort included female patients aged 40 years or older with no prior history of breast cancer undergoing a screening mammogram examination. Data were collected from January 1, 2015, to December 31, 2017, and analysis was conducted from January 2021 to September 2022. Exposures: A k-means clustering machine learning algorithm was used to classify patient insurance plans by dominant cost-sharing mechanism. Plan types were then ranked by OOPCs. Main Outcomes and Measures: A multivariable 2-part hurdle regression model was used to examine the association between patient OOPCs and the number and type of diagnostic breast services undergone by patients observed to undergo subsequent testing. Results: In our sample, 230 845 women (220 023 [95.3%] aged 40 to 64 years; 16 810 [7.3%] Black, 16 398 [7.1%] Hispanic, and 164 702 [71.3%] White) underwent a screening mammogram in 2016. These patients were covered by 22 828 distinct insurance plans associated with 6 025 741 enrollees and 44 911 473 distinct medical claims. Plans dominated by coinsurance were found to have the lowest mean (SD) OOPCs ($945 [$1456]), followed by balanced plans ($1017 [$1386]), plans dominated by copays ($1020 [$1408]), and plans dominated by deductibles ($1186 [$1522]). Women underwent significantly fewer subsequent breast imaging procedures in dominantly copay (24 [95% CI, 11-37] procedures per 1000 women) and dominantly deductible (16 [95% CI, 5-28] procedures per 1000 women) plans compared with coinsurance plans. Patients from all plan types underwent fewer breast magnetic resonance imaging (MRI) scans than patients in the lowest OOPC plan (balanced, 5 [95% CI, 2-12] MRIs per 1000 women; copay, 6 [95% CI, 3-6] MRI per 100 women; deductible, 6 [95% CI, 3-9] MRIs per 1000 women. Conclusions and Relevance: Despite policies designed to remove financial barriers to access for breast cancer screening, significant financial barriers remain for women at risk of breast cancer.

Recent trends in high-volume Medicare stroke thrombectomy provider characteristics.

BACKGROUND: Intracranial mechanical thrombectomy (MT) is increasingly indicated for use in acute ischemic stroke patients. We analyzed recent trends in the characteristics and geographic distributions of physicians providing this service with frequency to Medicare beneficiaries. METHODS: We linked public data sources to elucidate and visualize trends in high-volume MT providers between 2016 and 2019. RESULTS: High-volume MT providers increased by 184% between 2016 and 2019. The number of neurosurgeons, neurologists, and radiologists in this physician population increased by 251%, 205%, and 139%, respectively. Male practitioners accounted for 96% of providers in the most recent year of analysis. International medical graduates accounted for roughly one-third of these physicians across all 4 years of analysis. As of 2019, the three states with the most high-volume MT providers were Florida, California, and Texas, accounting for 7%, 7%, and 6% of providers, respectively. CONCLUSIONS: High-volume providers of MT services for Medicare beneficiaries represent a dynamic and rapidly expanding subset of physicians with diverse specialty backgrounds.

Association and Trends in Medicare Denials and Utilization for Brain CT: Indirect Impacts by Targeted Policy Intervention?

Twenty-five years of annual Medicare Physician/Supplier Procedure Summary (PSPS) Master File data were used to assess trends in normalized volume and claim denial rates for brain computerized tomography. Alongside growth in utilization of brain computerized tomography (services, denial rates, fell from 1999-2005 and with relatively leveled growth and less denial rate volatility thereafter. More recent trends in denial rates may be related to policy interventions initially aimed at cost and volume reduction.

Utilization of Chest and Abdominopelvic CT for Traumatic Injury From 2011 to 2018: Evaluation Using a National Commercial Database.

BACKGROUND. Increases in the use of CT to evaluate patients presenting with trauma have raised concern about inappropriate imaging. The evolving utilization of CT for trauma evaluation may be impacted by injury severity. OBJECTIVE. The purpose of this study was to explore patterns in utilization of chest and abdominopelvic CT among trauma-related emergency department (ED) visits across the United States. METHODS. This retrospective study was conducted with national commercial claims information extracted from the MarketScan Commercial Database. Trauma-related ED encounters were identified from the 2011-2018 MarketScan database files and classified by injury severity score (minor, intermediate, and major injuries) on the basis of International Classification of Diseases codes. ED encounters were also assessed for chest CT, abdominopelvic CT, and single-encounter chest and abdominopelvic CT examinations. Utilization per 1000 trauma-related ED encounters was determined. Multivariable Poisson regression models were used to determine incidence rate ratios (IRRs) as a measure of temporal changes in utilization. RESULTS. From 2011 to 2018, 8,369,092 trauma-related ED encounters were identified (5,685,295 for minor, 2,624,944 for intermediate, and 58,853 for major injuries). Utilization of chest CT per 1000 trauma-related ED encounters increased from 4.9 to 13.5 examinations (adjusted IRR, 1.15 per year; minor injuries, from 2.2 to 7.7 [adjusted IRR, 1.17]; intermediate injuries, from 8.5 to 21.5 [adjusted IRR, 1.16]; major injuries, from 117.8 to 200.1 [adjusted IRR, 1.08]). Utilization of abdominopelvic CT per 1000 trauma-related ED encounters increased from 7.5 to 16.4 (adjusted IRR, 1.12; minor injuries, 4.8 to 12.2 [adjusted IRR, 1.13]; intermediate injuries, 10.6 to 21.7 [adjusted IRR, 1.13]; major injuries, 134.8 to 192.6 [adjusted IRR, 1.07]). Utilization of single-encounter chest and abdominopelvic CT per 1000 trauma-related ED encounters increased from 3.4 to 8.9 [adjusted IRR, 1.16; minor injuries, 1.1 to 4.6 [adjusted IRR, 1.18]; intermediate injuries, 6.4 to 16.4 [adjusted IRR, 1.16]; major injuries, 99.6 to 179.9 [adjusted IRR, 1.08]). CONCLUSION. National utilization of chest and abdominopelvic CT for trauma-related ED encounters increased among commercially insured patients from 2011 to 2018, particularly for single-encounter chest and abdominopelvic CT examinations and for minor injuries. CLINICAL IMPACT. Given concerns about increased cost and detection of incidental findings, further investigation is warranted to explore the potential benefit of single-encounter chest and abdominopelvic CT examinations of patients with minor injuries and to develop strategies for optimizing appropriateness of imaging orders.

Professional Services Rendered by Nurse Practitioners and Physician Assistants Employed by Radiology Practices: Characteristics and Trends From 2017 Through 2019.

PURPOSE: With radiology practices increasingly employing nonphysician practitioners (NPPs), we aimed to characterize specific NPP clinical roles. METHODS: Linking 2017 to 2019 Medicare data sets, we identified all claims-submitting nurse practitioners and physician assistants (together NPPs) employed by radiologists. NPP-billed services were identified, weighted by work relative value units, and categorized as (1) clinical evaluation and management (E&M), (2) invasive procedures, and (3) noninvasive imaging interpretation. NPP practice patterns were assessed temporally and using frequency analysis. RESULTS: As the number of radiologist-employed NPPs submitting claims increased 16.3% (from 523 in 2017 to 608 in 2019), their aggregate Medicare fee-for-service work relative value units increased 17.3% (+40.0% for E&M [from 79,540 to 111,337]; +5.6% for procedures [from 179,044 to 189,003]; and +74.0% for imaging [from 5,087 to 8,850]). The number performing E&M, invasive procedures, and imaging interpretation increased 7.6% (from 329 to 354), 18.3% (from 387 to 458), and 31.8% (from 85 to 112), with 58.2%, 75.3%, and 18.4% billing those services in 2019. Paracentesis and thoracentesis were the most frequently billed invasive procedures. Fluoroscopic swallowing and bone densitometry examinations were the most frequently billed imaging services. By region, NPPs practicing as majority clinical E&M providers were most common in the Midwest (33.5%) and South (33.0%), majority proceduralists in the South (53.1%), and majority image interpreters in the Midwest (50.0%). CONCLUSIONS: As radiology practices employ more NPPs, radiologist-employed NPPs' aggregate services have increased for E&M, invasive procedures, and imaging interpretation. Most radiologist-employed NPPs perform invasive procedures and E&M. Although performed by a small minority, imaging interpretation has shown the largest relative service growth.

Osteopathic Versus Allopathic Radiologist Workforce Characteristics: A Medicare Administrative and Claims Data Analysis.

PURPOSE: Radiologist medical school pathways have received little attention in recent workforce investigations. With osteopathic enrollment increasing, we assessed the osteopathic versus allopathic composition of the radiologist workforce. METHODS: Linking separate Medicare Doctors and Clinicians Initiative databases and Physician and Other Supplier Files from 2014 through 2019, we assessed (descriptively and using multivariate panel logistic regression modeling) individual and practice characteristics of radiologists who self-reported medical degrees. RESULTS: Between 2014 and 2019, as the number of osteopathic radiologists increased 46.0% (4.7% to 6.0% of total radiologist workforce), the number of allopathic radiologists increased 12.1% (representing a relative workforce decrease from 95.3% to 94.0%). For each year since completing training, practicing radiologists were 3.7% less likely to have osteopathic (versus allopathic) degrees (odds ratio [OR] = 0.96 per year, P < .01). Osteopathic radiologists were less likely to work in urban (versus rural) areas (OR = 0.95), and compared with the Midwest, less likely to work in the Northeast (OR = 0.96), South (OR = 0.95), and West (OR = 0.94) (all P < .01). Except for cardiothoracic imaging (OR = 0.78, P = .24), osteopathic radiologists were more likely than allopathic radiologists to practice as general (rather than subspecialty) radiologists (range OR = 0.37 for nuclear medicine to OR = 0.65 for neuroradiology, all P < .01). CONCLUSIONS: Osteopathic physicians represent a fast-growing earlier-career component of the radiologist workforce. Compared with allopathic radiologists, they more frequently practice as generalist radiologists, in rural areas, and in the Midwest. Given recent calls for greater general and rural radiology coverage, increasing osteopathic representation in the national radiologist workforce could improve patient access.

Characteristics of Radiologists Serving as Medical Malpractice Expert Witnesses for Defense Versus Plaintiff.

PURPOSE: Previous studies have reported higher qualification characteristics for anesthesiologists, neurosurgeons, orthopedic surgeons, and otolaryngologists serving as defense (versus plaintiff) medical malpractice expert witnesses. We assessed such characteristics for radiologist expert witnesses. METHODS: Using the Westlaw legal research database, we identified radiologists serving as experts in all indexed medical malpractice cases between 2010 and 2019. Online databases were used to identify years of practice experience and scholarly bibliometrics. Using Medicare claims, individual radiologist practice types and mixes were ascertained. Radiologists testifying at least once each for defense and plaintiff were excluded from our defense-only versus plaintiff-only comparative analysis. RESULTS: Initial Boolean searches yielded 1,042 potential cases; subsequent manual review identified 179 radiologists testifying in 231 lawsuits: 143 testified in one case (58 defense, 85 plaintiff) and 36 testified in multiple cases (10 defense-only, 14 plaintiff-only, 12 both). The 68 defense-only experts had fewer years of practice experience than the 99 plaintiff-only experts (28.3 versus 31.8 years, P = .02), but the two groups were otherwise similar in both practice type (44.6% versus 54.9% academic, P = .62) and mix (63.8% versus 65.8% practiced as subspecialists, P = .37) and as well as numbers of publications (60.5 versus 62.8, P = .86), citations (1,994.1 versus 2,309.2, P = .56), and h-indices (17.2 versus 16.8, P = .89). CONCLUSIONS: In contrast to other specialists, radiologists serving as medical malpractice expert witnesses for defense and plaintiff display similar qualifications across various characteristics. Published practice parameter guidelines and experts' ability to blindly review archived original images might together explain this interspecialty discordance.

Radiology Practices Employing Nurse Practitioners and Physician Assistants: Characteristics and Trends From 2017 Through 2019.

PURPOSE: The number and roles of US nonphysician practitioners (NPPs) have expanded considerably, but little is known about their use by radiology practices. The authors assessed characteristics and trends of radiology practices employing Medicare-recognized NPPs. METHODS: Using Medicare databases from 2017 through 2019, the authors mapped all nurse practitioners and physician assistants (together "NPPs") to employer groups for which all physicians were radiologists ("radiology practices"). Practices were characterized by size, geography, and radiologist characteristics. Temporal changes were assessed, and NPP employment likelihood was estimated using multivariate logistic regression modeling. RESULTS: As the number of US radiology practices declined by 36.5% (from 2,643 to 1,679) between 2017 and 2019, the number employing NPPs increased by 10.5% (from 228 [8.6%] to 252 [15.0%]). The number of radiologists in NPP-employing practices increased by 10.4% (from 6,596 [35.1%] to 7,282 [40.0%]) as the number of radiology-employed NPPs increased by 17.5% (from 588 to 691). Practices were more likely to employ NPPs when medium (odds ratio [OR], 1.31) or large (OR, 1.25) in size, when urban located (OR, 1.35), and as their percentages of interventional radiologists increased (OR, 5.53 per percentage point) (P < .01 for all). Practices were less likely to employ NPPs as mean radiologist years since completing training increased (OR, 0.99 per year; P < .01). CONCLUSIONS: Employment of NPPs by radiology practices has grown considerably in recent years, particularly in larger and urban practices and in those that employ more interventional and early-career radiologists. More work is necessary to better understand how this expanding use of NPPs affects the specialty.

Assessment of wheeled mobility devices provided to a commercially insured population in 2017.

In the United States, wheeled mobility devices (WMD) are classified as durable medical equipment (DME). Consistent with the definition of DME, wheeled mobility devices are typically covered by health insurance when deemed medically necessary. Despite the number of persons using wheelchairs, little knowledge is available about the types of wheelchairs provided, user's specific diagnoses and the costs associated with WMD provision. The objective of this analysis was to define the number and types of wheelchairs and associated seating and mobility (S&M) accessories provided in the calendar year 2017. The analysis focused on user demographics, categories of WMDs and associated S&M equipment as well as cost accounting according to the type of insurance and contributions by beneficiaries. Analysis of over 81,000 wheelchair acquisitions found that manual wheelchairs accounted for nearly 90% with standard manual wheelchairs accounting for 86% of all wheelchairs provided. Wheelchair recipients tended to be older with the majority being female. Based upon ICD-10 diagnostic categories over 50% of captured ICD-10 codes came from three classifications, musculoskeletal (M), circulatory (I) and a general category of not otherwise classified disorders (R). Costs associated with seating and mobility equipment were fairly large, exceeding $79 million over a single calendar year.

Evolving Radiology Trainee Neuroimaging Workloads: A National Medicare Claims-based Analysis.

RATIONALE AND OBJECTIVES: While radiology training programs aim to prepare trainees for clinical practice, the relationship between trainee, and national radiology workforce demands is unclear. This study assesses changing radiology trainee neuroimaging workloads nationwide for neuroimaging studies. MATERIALS AND METHODS: Using aggregate Medicare claims files from 2002 to 2018, we identified all computed tomography (CT) and magnetic resonance (MR) examinations of the brain, head and neck, and spine (hereafter "neuroimaging") in Medicare fee-for-service beneficiaries nationwide. Using separate Medicare files, we calculated population utilization rates, and work relative value unit (wRVU) weights of all diagnostic neuroradiology services. Using claims modifiers, we identified services rendered by radiology trainees. Using separate national trainee enrollment files, we calculated mean annual per trainee wRVUs. RESULTS: Between 2002 and 2018, total Medicare neuroimaging claims increased for both radiologists overall (86.1%) and trainees (162.5%), including increases in both CT (102.9% vs 196.8%), and MR (59.9% vs 106.6%). The national percentage of all radiologist neuroimaging wRVUs rendered by trainees increased 46.1% (3.8% of all wRVUs nationally in 2002 to 5.6% in 2018). National trainee increases were present across all neuroimaging services but greatest for head and neck CT (+86.5%). Mean annual per radiology trainee neuroimaging Medicare wRVUs increased +174.9% (42.1 per trainee in 2002 to 115.70 in 2018). Mean per trainee wRVU increases were greatest for spine CT (+394.2%) but present across all neuroimaging services. CONCLUSION: As neuroimaging utilization in Medicare beneficiaries has grown, radiology trainee neuroimaging workloads have increased disproportionately.

Nurse practitioner scope of practice and the prevention of foot complications in rural diabetes patients.

PURPOSE: Diabetic foot ulcers afflict a quarter of type-2 diabetes mellitus patients and are associated with higher mortality rates among people with diabetes. Routine primary and preventive care is essential to both prevent and treat foot ulcers before they can contribute to further adverse outcomes. One approach for expanding this care to people with diabetes in rural communities is increasing the practice authority of nurse practitioners. This study examines whether the presence of nurse practitioner practice authority is associated with fewer foot ulcer complications in rural populations as measured through the incidence of foot debridement-a common procedure for addressing severe diabetic foot ulcers. METHODS: This study uses medical claims to estimate the incidence of foot debridement for US counties. A multivariable linear regression was performed to examine the association between nurse practitioner practice authority and the county incidence of foot debridement after adjusting for measures of local health care workforce and sociodemographics. FINDINGS: Nurse practitioner practice authority was associated with 219.4 fewer foot debridements per 10,000 enrollees (P < .001) in rural counties. Rural health clinics (P < .03) and skilled nursing facilities (P < .03) were also associated with fewer rural debridements. The number of nurse practitioners (P < .69) and primary care physicians (P < .69) per enrollee were not significant. No measure of health care workforce was associated with the incidence of foot debridement in urban counties. CONCLUSIONS: Expanding nurse practitioner practice authority may be an effective solution for preventing complications from diabetic foot ulcers in rural communities.

Increasing Utilization of Emergency Department Neuroimaging From 2007 Through 2017.

BACKGROUND. The volume of emergency department (ED) visits and the number of neuroimaging examinations have increased since the start of the century. Little is known about this growth in the commercially insured and Medicare Advantage populations. OBJECTIVE. The purpose of our study was to evaluate changing ED utilization of neuroimaging from 2007 through 2017 in both commercially insured and Medicare Advantage enrollees. METHODS. Using patient-level claims from Optum's deidentified Clinformatics Data Mart database, which annually includes approximately 12-14 million commercial and Medicare Advantage health plan enrollees, annual ED utilization rates of head CT, head MRI, head CTA, neck CTA, head MRA, neck MRA, and carotid duplex ultrasound (US) were assessed from 2007 through 2017. To account for an aging sample population, utilization rates were adjusted using annual relative proportions of age groups and stratified by patient demographics, payer type, and provider state. RESULTS. Between 2007 and 2017, age-adjusted ED neuroimaging utilization rates per 1000 ED visits increased 72% overall (compound annual growth rate [CAGR], 5%). This overall increase corresponded to an increase of 69% for head CT (CAGR, 5%), 67% for head MRI (CAGR, 5%), 1100% for head CTA (CAGR, 25%), 1300% for neck CTA (CAGR, 27%), 36% for head MRA (CAGR, 3%), and 52% for neck MRA (CAGR, 4%) and to a decrease of 8% for carotid duplex US (CAGR, -1%). The utilization of head CT and CTA of the head and neck per 1000 ED visits increased in enrollees 65 years old or older by 48% (CAGR, 4%) and 1011% (CAGR, 24%). CONCLUSION. Neuroimaging utilization in the ED grew considerably between 2007 and 2017, with growth of head and neck CTA far outpacing the growth of other modalities. Unenhanced head CT remains by far the dominant ED neuroimaging examination. CLINICAL IMPACT. The rapid growth of head and neck CTA observed in the fee-for-service Medicare population is also observed in the commercially insured and Medicare Advantage populations. The appropriateness of this growth should be monitored as the indications for CTA expand.