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Trends in the Utilization of MR Angiography and Body MR Imaging in the U.S. Medicare Population: 1993–1998¹

¹ From the Department of Radiology, Thomas Jefferson University Hospital, 111 S 11th St, Philadelphia, PA 19107. From the 2000 RSNA scientific assembly. Received February 13, 2001; revision requested March 30; revision received June 20; accepted August 15. Address correspondence to B.J.L. (e-mail: blivstone@aol.com).

	ABSTRACT

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PURPOSE: To determine the trends in utilization of nonneurologic (ie, body) magnetic resonance (MR) imaging and of MR angiographic examinations performed from 1993 to 1998, the trends in nonradiologist participation in MR imaging, and the relative reimbursements for these examinations compared with those for all other noninvasive imaging studies performed in 1998.

MATERIALS AND METHODS: By using the 1993, 1996, and 1998 nationwide Medicare Part B databases, utilization rates per 100,000 Medicare beneficiaries and physician reimbursements were determined for seven MR angiography and 14 body MR imaging CPT-4 (Current Procedural Terminology, version 4) codes. Medicare specialty codes were used to categorize physicians as radiologists or nonradiologists.

RESULTS: The utilization rate per 100,000 Medicare beneficiaries for all 21 MR angiography and body MR imaging codes increased from 649 in 1993 to 1,253 in 1996 and to 1,876 in 1998—a 189% increase. These rates represented 0.55% of the total noninvasive imaging volume in 1998 and 2.8% of physician reimbursements. Musculoskeletal MR imaging utilization increased 142% from 1993 to 1998 compared with a 58% increase in the utilization of other body MR imaging studies. Nonradiologist participation in musculoskeletal MR imaging increased from 2.9% in 1993 to 3.6% in 1996 and to 5.6% in 1998.

CONCLUSION: MR angiography and body MR imaging utilization rates increased substantially from 1993 to 1998. However, these studies still account for a minor fraction of all noninvasive imaging examinations performed and fees reimbursed. MR angiography and musculoskeletal MR imaging utilization has increased rapidly. Nonradiologist participation in musculoskeletal MR imaging is increasing.

© RSNA, 2002

Index terms: Economics, medical • Magnetic resonance (MR), utilization • Radiology and radiologists, socioeconomic issues

	INTRODUCTION

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Since magnetic resonance (MR) imaging became a clinical reality in 1982, multiple studies have been undertaken to quantify the economic effect of this modality on health care in the United States. The majority of these investigations occurred in the early 1990s. Probably the most notable of these studies, that conducted by Evens and Evens (1), involved the evaluation of MR data obtained from 1985 through 1990. Although rapid growth was reported during this period, some authors (1–3) predicted a decrease in the demand for MR imaging services with a concomitant decline in the favorable economic position of MR imaging.

In this study, we had three goals. The first goal was to determine the trends in the utilization of nonneurologic (ie, body) MR imaging and all MR angiographic examinations performed in the U.S. Medicare population from 1993 to 1998. The second goal was to determine the trends in the amount of participation by nonradiologists in the billing for these services. The third goal was to determine the reimbursements for these examinations as compared with those for all other noninvasive imaging studies performed in 1998. Neurologic MR imaging (with exception of MR angiography) data were excluded because these cost and participation figures were reviewed by Rao et al (4,5) in their assessment of nonradiologist participation in neurologic MR imaging studies.

	MATERIALS AND METHODS

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Institutional review board approval and informed consent were not required for this study. Our data sources were the 1993, 1996, and 1998 Health Care Financing Administration Physician/Supplier Procedure Summary master files. This data set is an aggregation of Medicare Part B annual data reimbursement files. The Medicare database is a unique resource: It enables an assessment that is not possible for any other population. All claims for professional services are filed under the Medicare Part B program. The billions of claims are reduced to 11 million records, which are categorized according to the procedural code under which the claim is filed, the specialty code of the physician provider, and the exact reimbursement allowed for that claim. For imaging examinations, Medicare generally reimburses hospital-based physicians through professional component claims and office-based physicians through total component (or global) claims. The latter incorporates both the technical and professional costs of the procedure.

In this study, both types of physician payments—that is, hospital based and office based—were aggregated. Medicare uses approximately 90 specialty codes. For our purposes, physicians who identified themselves as diagnostic radiologists, interventional radiologists, or nuclear medicine physicians were classified as radiologists, whereas all other physicians were classified as nonradiologists. Payments to hospitals for the technical component of radiologic services are primarily under Part A of the Medicare program and thus were not included in this analysis.

We selected seven MR angiography codes and 14 body MR imaging codes from the 1993, 1996, and 1998 Current Procedural Terminology, version 4 (CPT-4) codes, which represent all MR angiographic (both body and neurologic) and all nonneurologic MR imaging examinations (6–8). In addition to a separate category for MR angiography, the body MR imaging codes were categorized for cardiac, musculoskeletal, and other body MR imaging examinations. The other body imaging category consists of thoracic, abdominal, pelvic, and breast MR imaging examinations (Table 1). There are no separate CPT-4 codes for other body or musculoskeletal MR examinations with contrast material, and it is acknowledged that some departments use MR angiography codes for such examinations. The extent of this practice could not be determined and may represent another limitation of the data.

A common criticism of MR imaging is that its high costs are a burden on the nation’s health care system. To determine the relative costs (in reimbursements) for MR angiography and body MR imaging as compared with those for all other noninvasive imaging examinations, we also tabulated the reimbursements for each MR angiography and body MR imaging category. In calculating the numbers of and reimbursements for all noninvasive imaging examinations performed in 1998, we assessed all of the noninvasive imaging codes in the 70000 CPT series for conventional radiography, fluoroscopy, mammography, ultrasonography (US), computed tomography, MR imaging, and nuclear medicine. We also included the codes in the 90000 series that pertained to echocardiography and vascular US. We excluded from this calculation those supervision and interpretation codes related to invasive procedures, radiation oncology, and therapeutic nuclear medicine in the 70000 series. Since the rates obtained are complete counts of the entire Medicare population rather than counts of a sample from the population, no inferential statistics were required.

	RESULTS

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A total of 649 MR angiographic and body MR imaging examinations were performed per 100,000 Medicare beneficiaries in 1993, as compared with 1,253 examinations in 1996 and 1,876 in 1998. The utilization rates per 100,000 Medicare beneficiaries for each of the four categories of MR imaging performed in 1993, 1996, and 1998 are listed in Table 2. MR angiography codes did not exist in 1993.

	DISCUSSION

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To many, the impending takeover by health maintenance organizations was synonymous with an end to high technology utilization (2). However, despite decreasing reimbursements, MR imaging unit installations have yielded profits. Evens and Evens (1) observed that revenues from MR imaging units had improved from an average $400,000 loss per unit in 1982 to a $500,000 profit per unit in 1990. The continued profitability has been due largely to improved efficiency. For instance, the number of scheduled hours of MR imaging unit operation per day in the United States is 1.6 times higher than that in Japan (10). Although scheduling issues and room preparation time continue to limit throughput, increases in throughput have been possible owing to the development of more rapid pulse sequences that enable the acquisition of images in less than 1 second, such as single-shot fast spin echo. The demand for MR imaging studies also has increased. As MR applications expand and clinicians become more familiar with the technology and its results, the modality is being incorporated into standard diagnostic work-ups. These factors contributed to a 189% increase in MR angiography and body MR imaging utilization from 1993 to 1998.

The utilization of musculoskeletal MR imaging increased substantially, as did the use of MR angiography and other body MR imaging examinations. It is interesting that there was virtually no growth in the use of cardiac MR imaging despite an active research base for clinical applications. Although this may be because cardiac MR imaging has not yet emerged as an established modality, referral patterns also may be a factor. As demonstrated in the study by Levin et al (11), cardiac-related imaging, which is performed predominantly by cardiologists, accounts for approximately one-third of the total imaging-related health care costs. As cardiac MR imaging techniques improve and this modality becomes more established, it should have considerable additional growth potential. However, it remains to be seen whether this technology will remain under the aegis of radiologists as all other types of MR imaging are.

Nonradiologist participation in cardiac MR imaging has been decreasing: It decreased from 21.1% in 1993 to 14.3% in 1998. It is interesting that nonradiologist participation in MR angiography has not increased either: It was 4.7% in 1998. However, the overall rate of nonradiologist participation in the MR imaging categories covered in this study has been increasing: Nonradiologist participation increased from 2.8% in 1993 to 4.9% in 1998. The greatest increase in nonradiologist participation was in musculoskeletal MR imaging, with 5.6% participation in 1998 compared with 2.9% participation in 1993. Musculoskeletal MR imaging is also the fastest growing category of nonneurologic MR imaging—that is, the use of this modality is increasing the fastest.

The results of the Levin et al (11) study demonstrated that in 1993, the overall economic effect of all MR imaging examinations, as compared with that of all the other imaging modalities, was small, accounting for only 7% of all imaging costs. Surprisingly, MR angiography and body MR imaging represented only 0.55% of all noninvasive imaging examinations performed and 2.8% of all physician reimbursements for noninvasive imaging in 1998, according to our study data. These data do not include the volume of and reimbursements for neurologic MR imaging, which accounts for a majority of all MR imaging examinations. However, these data do further refute the notion that MR imaging represents a major financial burden on the nation’s health care system. It should be noted that although MR imaging examinations account for a small percentage of both the total costs and the total number of noninvasive imaging examinations performed, the comparisons may be somewhat misleading since MR imaging is more costly than other noninvasive imaging examinations on an individual basis. Therefore, the contribution of MR imaging to total expenditures may increase as the use of MR imaging increases. However, the extent of this increase cannot be ascertained since many additional factors, such as the charges for individual MR imaging examinations, may fluctuate and new CPT-4 codes may be created to account for more limited and focused MR examinations, with the result of decreased costs.

One limitation of these data is that they do not include Medicare Part A payments to hospitals, which cover the technical components of the costs of imaging performed in hospital settings. Part A payments were not included because the technical component costs of imaging are subsumed within the overall diagnosis-related group payments and thus cannot be specifically identified. This exclusion probably caused an underestimation of the total Medicare expenditures for each of the MR imaging procedures studied.

Another limitation is that the Medicare database provides complete nationwide information for less than one-third of all patients in the United States. The exclusion of the younger population could be a concern, especially since musculoskeletal MR imaging is performed predominantly in younger patients. However, to our knowledge, no nationwide database of the population of patients younger than 65 years is available. It is likely that if this population had been studied, the growth in musculoskeletal MR imaging utilization would have been somewhat greater and that in MR angiography utilization would have been somewhat lower.

In conclusion, MR angiography and body MR imaging utilization rates increased substantially from 1993 to 1998. However, these examinations still account for only a minor fraction of all noninvasive imaging examinations performed and of costs to the U.S. health care system. Use of MR angiography and musculoskeletal MR imaging has increased the most. Nonradiologist participation in musculoskeletal MR imaging is increasing.

	FOOTNOTES

 
Author contributions: Guarantors of integrity of entire study, B.J.L., L.P., D.C.L.; study concepts and design, B.J.L., L.P., D.C.L.; literature research, B.J.L.; data acquisition, L.P.; data analysis/interpretation, B.J.L., L.P., D.C.L.; manuscript preparation, B.J.L.; manuscript definition of intellectual content, editing, and final version approval, B.J.L., L.P., D.C.L.; manuscript revision/review, B.J.L., D.C.L.

	REFERENCES

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1. Evens RG, Evens RG, Jr. Analysis of economics and use of MR imaging units in the United States in 1990. AJR Am J Roentgenol 1991; 157:603-607.
2. Baker LC, Wheeler SK. Managed care and technology diffusion: the case of MRI. Health Aff 1998; 17:195-207.
3. Hensley S. MRI renaissance. Mod Health Care 1997; 27:57-62.
4. Rao VM, Levin DC, Spettell CM, Sunshine JH, Bansal S. Who performs neuroimaging? Results from the 1993 national Medicare database. Radiology 1997; 204:443-445.
5. Rao VM, Parker L, Levin DC, Sunshine JH, Bushee G. Variation in the rates of utilization of neuroimaging studies in different geographic regions of the USA (abstr). Radiology 1999; 213(P):483.
6. American Medical Association. Physician’s current procedural terminology Chicago, Ill: American Medical Association, 1993.
7. American Medical Association. Physician’s current procedural terminology Chicago, Ill: American Medical Association, 1996.
8. American Medical Association. Physician’s current procedural terminology Chicago, Ill: American Medical Association, 1998.
9. Mettler FA, Briggs JE, Carchman R, Altobelli KK, Hart BL, Kelsey CA. Use of radiology in U.S. general short-term hospitals: 1980–1990. Radiology 1993; 189:377-380.
10. Hisashige A. MR imaging in Japan and the United States: analysis of utilization and economics. AJR Am J Roentgenol 1994; 162:507-510.
11. Levin DC, Spettell CM, Rao VM, Sunshine JH, Bansal S, Bushee GR. Impact of MR imaging on nationwide health care costs and comparison with other imaging procedures. AJR Am J Roentgenol 1998; 170:557-560.

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This Article Abstract Full Text (PDF) All Versions of this Article: 2223010460v1 222/3/615    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Livstone, B. J. Articles by Levin, D. C. Search for Related Content PubMed PubMed Citation Articles by Livstone, B. J. Articles by Levin, D. C.