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Cardiovascular Imaging

Who Does It and How Important Is It to the Practice of Radiology?

¹ Department of Radiology, Thomas Jefferson University Hospital, 111 S. 11th St., Philadelphia, PA 19107.
² American College of Radiology, 1891 Preston White Dr., Reston, VA 20191.
³ Department of Radiology, Georgetown University Medical Center, 3800 Reservoir Rd. N.W., Washington, DC 20007.

Received July 16, 2002; accepted after revision August 23, 2002.

 
Address correspondence to D. C. Levin.

Abstract

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OBJECTIVE. Our research was conducted to ascertain the importance of noninvasive cardiovascular imaging to the practice of radiology and to determine what percentages of noninvasive cardiovascular imaging are performed by radiologists and by other types of physicians.

MATERIALS AND METHODS. Using the national 1998 Medicare Part B database, we reviewed all 460 procedure codes pertaining to noninvasive diagnostic imaging and identified 65 that were specifically related to the cardiovascular system. These 65 codes were grouped in five categories: cardiac MR imaging, MR angiography, cardiovascular nuclear medicine, echocardiography, and vascular sonography. For each code and category, we determined the nationwide examination volume, the utilization rate per 1,000 Medicare fee-for-service enrollees, Part B physician reimbursements, and the percentages of examinations performed by radiologists, cardiologists, surgeons, and other physicians.

RESULTS. During 1998, 19,244,001 noninvasive cardiovascular imaging studies were performed on Medicare enrollees, which accounted for 17.7% of all Medicare diagnostic imaging studies carried out that year and 33.6% of all Part B imaging-related reimbursements paid. The utilization rate for noninvasive cardiovascular imaging was 603 per 1,000 Medicare enrollees per year. Echocardiography alone accounted for 63.4% of these examinations. Radiologists conducted 16.7% of all noninvasive cardiovascular imaging, whereas cardiologists conducted 61.5%, surgeons 4.8%, and other physicians 16.9% of the examinations. The strong role of cardiologists was largely attributable to their dominance in echocardiography. Radiologists had a substantial role in all categories except echocardiography.

CONCLUSION. Noninvasive cardiovascular imaging represents an important component of the practice of radiology. Radiologists have substantial participation in all aspects of the field with the exception of echocardiography.

Introduction

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In 1999, four of the leading national radiology organizations—the American Board of Radiology, the American College of Radiology, the American Roentgen Ray Society, and the Radiological Society of North America—formed the Committee for Cardiovascular Imaging. The impetus for this action was the belief that a concerted effort is needed to advance noninvasive cardiovascular imaging within the radiology community, especially at a time when rapid strides are occurring in cardiovascular MR imaging and CT [1, 2].

The Committee for Cardiovascular Imaging came together with the mission "to improve patient care by advancing clinical practice, research, and education in the imaging of cardiovascular disease, with particular attention to evolving modalities such as computed tomography and magnetic resonance imaging." [1] The committee first met in July 1999 in Reston, VA. Some of the principal goals the group decided to pursue were curriculum development for residency training in noninvasive cardiovascular imaging, sponsorship of continuing medical education programs, promotion of sponsored research and research fellowships, development of credentialing and guidelines documents, promotion of access to quality cardiovascular imaging through accreditation, and consideration of how best to evaluate competence in cardiovascular imaging during the American Board of Radiology written and oral examinations.

As background for these activities, the group felt that an important initial objective was to determine how important a role noninvasive cardiovascular imaging plays within the myriad diseases studied by imaging methods. The primary question to be asked was, What proportion of all noninvasive diagnostic imaging does noninvasive cardiovascular imaging represent? (Or, to put it another way, How important is it to the practice of radiology?) A secondary question was, What are the roles of the radiologist, cardiologist, surgeon, and other physicians in noninvasive cardiovascular imaging?

Materials and Methods

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Our methods have been described previously [3, 4]. We used as our source the national 1998 Health Care Financing Administration Physician/Supplier Procedure Summary Master Files. These files comprise claims made for physician services to the 31.9 million fee-for-service enrollees in the Medicare Part B program that year. Medicare managed care enrollees are not included in this database. Each claim is categorized by type of service, using the Current Procedural Terminology, version 4 (CPT-4) codes. Each physician service is also classified by self-designated provider specialty, using one of 107 Health Care Financing Administration specialty codes.

For the purposes of this study, physicians were categorized as radiologists, cardiologists, surgeons, or other physicians. Physicians who were classified under one of three specialty codes—diagnostic radiology, interventional radiology, or nuclear medicine—were grouped together as radiologists. Physicians filing claims under the two specialty codes for cardiology and peripheral vascular disease were classified as cardiologists. Physicians filing claims under the two specialty codes for vascular surgery and general surgery were classified as surgeons. The remainder were grouped together as other physicians.

The 1998 CPT-4 coding manual listed 460 codes pertaining to noninvasive diagnostic imaging. These 460 codes included 65 codes pertaining to noninvasive cardiovascular imaging. Slightly more than half these cardiovascular imaging codes were listed in the 70000 CPT-4 series; the remainder (primarily for echocardiography and vascular sonography) were within the 90000 series. Each of these 65 codes were grouped into one of five categories: cardiac MR imaging (five codes), MR angiography (seven codes), cardiovascular nuclear medicine (22 codes), echocardiography (14 codes), and vascular sonography (17 codes). During 1998, no codes were available for CT angiography. No codes for invasive or surgical procedures were included in this study, nor were codes for their associated supervision and interpretation, because we intended to assess only noninvasive diagnostic imaging studies. Also excluded were codes in the 70000 series pertaining to radiation oncology and therapeutic nuclear medicine.

We determined the nationwide examination volume, utilization rate per 1,000 Medicare fee-for-service enrollees, and Medicare Part B physician reimbursements for the 65 noninvasive cardiovascular imaging codes and for the larger group of all 460 noninvasive diagnostic imaging codes. We then calculated what proportion noninvasive cardiovascular imaging represented of all noninvasive diagnostic imaging performed in this group of patients during 1998. We also determined the percentages of cardiovascular imaging examinations that were performed by radiologists, cardiologists, surgeons, and other physicians. For this part of the analysis, we had to exclude 7% of cardiovascular imaging studies because the specialty codes used in those claims did not permit determination of the provider physician's actual specialty. These specialty codes included the following designations: mammography screening center, voluntary health or charitable agency, portable X-ray supplier, independent laboratory, clinic or other group practice, and independent physiologic laboratory.

Diagnostic cardiac catheterization was not part of this analysis, because it is an invasive procedure. However, a separate analysis of these codes was carried out because of the possibility that they potentially could be replaced in the future by noninvasive MR imaging or CT.

Results

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Under all 460 codes for noninvasive diagnostic imaging, a total of 108,703,725 inpatient and outpatient examinations were performed in 1998, representing a utilization rate of 3,409 examinations per 1,000 Medicare fee-for-service beneficiaries. Medicare Part B physician reimbursements for these services totaled $5,081,543,417.

Table 1 lists the five categories of noninvasive cardiovascular imaging examinations along with the nationwide 1998 Medicare examination volume for each, the utilization rate per 1,000, and the aggregate Medicare Part B reimbursements paid. A total of 19,244,001 noninvasive cardiovascular imaging examinations were performed, representing a utilization rate of 603 per 1,000. Medicare Part B reimbursements for cardiovascular imaging totaled $1,709,687,577. Echocardiography represented almost two thirds of all noninvasive cardiovascular imaging examinations, with vascular sonography representing 19.9% and cardiovascular nuclear medicine, 15.8%. MR angiography and cardiac MR imaging together accounted for less than 1% of cardiovascular imaging.

Table 2 shows the percentages of the five different categories of noninvasive cardiovascular imaging that were performed by radiologists, cardiologists, surgeons, and other physicians. In the largest category, echocardiography, radiologists performed only 1.6% of the examinations. However, radiologists performed 44.8% of vascular sonography and 37.8% of cardiovascular nuclear medicine studies. Radiologists strongly predominated in both cardiac MR imaging and MR angiography, but these were relatively minor areas of practice in terms of examination volume. Cardiologists performed most of the cardiovascular nuclear medicine and echocardiographic examinations. Surgeons had only a minor role in cardiovascular imaging, except for vascular sonography examinations, 23.8% of which they performed. Those in the "other physicians" category had substantial roles in echocardiography (18.4%) and vascular sonography (20.0%). In echocardiography, 15.2% of the total 18.4% of studies were conducted by physicians designating themselves as internists. In vascular sonography, of the 20.0% of studies performed by other physicians, 10.3% were conducted by internists, 5.3% by neurologists, and 3.5% by thoracic surgeons.

Table 3 shows the percentages of total examinations performed and Part B reimbursements received for the four physician groups. Radiologists performed 16.7% of all cardiovascular imaging examinations, cardiologists performed 61.5%, surgeons performed 4.8%, and other physicians performed 16.9%. Radiologists received 13.8% of all Medicare Part B reimbursements for cardiovascular imaging, while cardiologists received 63.4%, surgeons received 4.4%, and other physicians received 18.4%.

We conducted a separate analysis of diagnostic cardiac catheterization. The various aspects of cardiac catheterization and coronary and ventricular angiography were covered by 25 codes. Total procedure volume within these codes was 4,625,744. The utilization rate per 1,000 was 145. Medicare Part B payments for these procedures totaled $413,466,598. Radiologists performed only 0.3% of cardiac catheterization and coronary and ventricular angiography.

Discussion

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The data offer interesting insight into the importance of cardiovascular imaging as part of the spectrum of noninvasive diagnostic imaging of all disease in this country. Among the nearly 109 million noninvasive diagnostic imaging examinations performed on Medicare fee-for-service patients in 1998, more than 19 million were cardiovascular imaging examinations. Among the nearly $5.1 billion paid by the Medicare program for physician services related to noninvasive diagnostic imaging in this population during 1998, more than $1.7 billion represented reimbursements for noninvasive cardiovascular imaging. Clearly, cardiovascular imaging is a major component of noninvasive diagnostic imaging: It constituted 17.7% of all noninvasive diagnostic imaging studies performed, and 33.6% of all Part B reimbursements paid. The reason the reimbursement percentage is so much higher than the volume percentage is that, overall, noninvasive diagnostic imaging is heavily weighted by conventional radiography, which is reimbursed at far lower rates than cardiovascular examinations such as echocardiography, vascular sonography, and nuclear medicine scans.

Cardiologists predominate in cardiovascular imaging, in that they performed 61.5% of the total examinations and received 63.4% of the Medicare reimbursements paid during 1998. However, this finding is largely the result of their strong dominance in echocardiography, which in itself accounts for almost two thirds of all cardiovascular imaging volume and more than half of all Part B reimbursements for cardiovascular imaging. Aside from echocardiography, radiologists maintain a solid presence in both vascular sonography and cardiovascular nuclear medicine, and they strongly predominate in MR studies of the heart and blood vessels.

A limitation of our data is that it underestimates the actual role of cardiovascular imaging because it does not include conventional radiography (e.g., chest radiographs) of patients whose primary medical problems are related to the heart and blood vessels. The database does not easily allow determination of the indications for these studies. If conventional radiography examinations for cardiovascular indications could be included, the role of cardiovascular imaging likely would be considerably greater, as would the degree of participation by radiologists.

The status of diagnostic cardiac catheterization needs to be considered in any discussion of the present and potential roles of noninvasive cardiovascular imaging. Our study found that the Medicare Part B program spent more than $413 million per year on diagnostic cardiac catheterizations performed on its fee-for-service enrollees, compared with approximately $1.7 billion spent on all noninvasive cardiovascular imaging. With the rapid advances being made in CT and MR imaging of the cardiac chambers, myocardium, and coronary arteries, it is quite possible that many diagnostic cardiac catheterization procedures could be replaced by these totally noninvasive examinations. Doing so would have obvious advantages in terms of cost savings, patient convenience, and risk avoidance.

In summary, noninvasive cardiovascular imaging has an important current role in the practice of radiology, and its future looks bright. One question for consideration by the radiology community is, What will be—or should be—the role of radiologists in this field? Cardiologists have clearly established a strong presence in cardiovascular imaging, and they control the patients. On the other hand, radiologists have far more technical knowledge of the complexities of CT and MR imaging. Thus, both disciplines offer something of value. In an editorial several years ago in the bulletin of the American College of Cardiology, the chairman of its board of governors reviewed the often contentious relationships between radiologists and cardiologists over such issues as exclusive contracting and self-referral in imaging, but concluded that the cardiovascular imaging specialist of the future will probably be a hybrid product [5]. It does seem likely that the goals of good patient care and advancement of the field will best be served by cooperation between the two groups, rather than confrontation. However, it also seems likely that if radiologists are to participate fully in its future, they must become more active in cardiovascular imaging research and education than they have been in the past.

References

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1. McLoud TC. Formation of Committee for Cardiovascular Imaging. AJR 2000;174:548
2. Committee for Cardiovascular Imaging. ACR Bulletin 1999;55(9):10 -34
3. Levin DC, Parker L, Eschelman DJ, Sunshine J, Busheé G. Do interventional radiologists pose a significant threat to the practice of vascular surgery? J Vasc Interv Radiol 1999;10:1007 -1011[Medline]
4. Levin DC, Parker L, Sunshine JH, Busheé G, Merritt CRB. Role of emergency medicine physicians in US performed in patients in the emergency department: how substantial is their participation? Radiology 2000;216:265 -268[Abstract/Free Full Text]
5. Wann LS. Self-referral and exclusive contracting. Cardiology 1999;28:8 -12

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