Cardiologists continue to invest in a variety of diagnostic imaging modalities, but according to a new survey, CT scanners lead the way.

As the dynamic world of cardiac imaging keeps advancing, definite trends in cardiac diagnostic techniques are slowly emerging. Although the current trend is toward more unobtrusive modalities such as CT and MR angiography, it is clear that echocardiography, nuclear perfusion (SPECT), and cardiac catheterization are still important diagnostic tools.

Dan DeGiorgio, director of cardiac solutions for Siemens Medical Solutions USA Inc in Malvern, Pa, said, “All imaging components are selling equally well in terms of the number of units, but CT is the big ticket, so the highest revenue is there.”

Despite the price, according to a new market research report, “Present Practices & Future Directions in Cardiac Imaging: The Cardiologist’s Perspective,” recently released by IMV Medical Information Division, a market research firm based in Des Plaines, Ill, acquisition of 64-slice CT equipment by cardiology practices throughout the United States has more than doubled over the past 2 years. Their survey found that 45% of the cardiology practices surveyed presently own or lease CT equipment. This averages out to about two units per practice among those who have such equipment. In contrast, according to an earlier IMV survey in 2006, only 23.5% of cardiac practices owned or leased CT equipment at that time, with an average of 1.4 units per practice.

Although cardiac catheterization has been the most important tool for evaluating the arteries of the heart, it is an invasive procedure that requires an incision in the groin, inserting a catheter into an artery in the leg, and advancing the catheter under x-ray guidance to the heart. Contrast dye is then injected directly into the arteries on the surface of the heart and x-rays are taken that show whether any of the vessels are narrowed.

On the other hand, cardiac CTA requires only a small IV in the arm. A small amount of dye is injected into the vein followed by a CT scan of the heart. With cardiac CT angiography, there is no risk of vascular damage, heart attack, or stroke. After the scan, the IV is removed and the patient can go home, go to work, or resume normal activities immediately.

According to the Princeton Longevity Center, nearly one out of every three people advised to have a cardiac catheterization ultimately find they do not have any significantly blocked arteries, so use of CTA can be an excellent way to avoid the risk of complications and eliminate the need for a stay in the hospital. 

Cardiac CT angiography is also a highly effective diagnostic tool for those people who have an abnormal stress test but are unlikely to have significant heart disease. In people with nondiagnostic (equivocal or borderline) stress tests, or those with “negative” stress tests but who are at high risk of coronary artery disease, CTA can quickly and noninvasively determine whether significant coronary artery disease is present. 

According to Mary C. Patton, director of market research for IMV, “In the 2006 survey, respondents predicted very substantial shifts away from traditional imaging modalities, such as diagnostic cardiac catheterization, to less invasive imaging procedures such as CT angiography and MR angiography. In general, such shifts have not occurred at the rate the 2006 cardiologists envisioned; one factor in this development is reimbursement.” Despite this, she added, “The shift away from cardiac catheterization has continued, with CTA replacing the older procedure as a primary diagnostic imaging modality for the evaluation of several major cardiac conditions.”

64-Slice Units Lead the Way

“Importantly, the majority of CT units out there in the cardiology practices are now 64-slice units,” Patton observed. “It’s extremely important for today’s cardiology practices to offer state-of-the-art imaging capabilities to maintain or improve their competitive edge and provide the best possible patient care. The perception of many cardiologists working in large private practices is that there’s no point in buying CT equipment that’s not 64-slice.”

The 2008 IMV survey, which explored the use of cardiac CT angiography, CT calcium scoring, cardiac MR and MR angiography, SPECT and SPECT/CT, PET and PET/CT, cardiac catheterization, and echocardiography, yielded some interesting results.

For example, an estimated three quarters (75%) of US cardiologists order some CT angiography exams on a monthly basis; up from 71.5% reported in the 2006 survey. The aggressive shifts of cardiac procedures to CT angiography and MR angiography have not occurred at the rate predicted by cardiologists in the 2006 survey. However, some shift of procedures continues to occur, particularly in the case of CT angiography.

Nevertheless, despite recent declines in the overall number of SPECT procedures performed, SPECT procedure volumes among responding cardiologists are stable or increasing. More than 60% of the cardiology practices represented in the survey sample presently own or lease at least one piece of SPECT or SPECT-CT equipment. Also, echocardiography continues to represent one of the top three diagnostic imaging modalities for 10 of the 12 cardiac conditions covered in the survey.

The IMV survey confirms that cardiologists continue to invest in a variety of diagnostic imaging modalities, including echocardiography, SPECT, and CT equipment. Yet, CT has shown the greatest increases in equipment purchases and installed units based within private cardiology practices.

Selection Criteria

Patton reports that cardiologists in the survey preferred to buy or lease new equipment, rather than buying refurbished equipment. This is, at least in part, due to their concerns about maintaining their competitive edge technologically and providing the highest level of patient care available. “Price continues to represent a critical selection criterion, although access to the latest technology is probably equally important,” Patton said.

Generating enough self-referral volume (and associated) reimbursement to cover their investment in the latest technologies is the key challenge for many cardiology practices. Rick Banner, product manager for Siemens, CT, said, “Leasing is going up because there is less risk.” He added, “No one is immune to the current recession, so cardiac imaging is a very cost-conscious environment.”

In this context, Philips is promoting its MX 16-slice CT units for those cost-conscious practices. The company’s 16-slice system is ideal for those customers who want to replace their current scanner or add a second system, but have purchasing cost concerns stemming from economic pressures. Philips’ 16-slice unit is a high-performing scanner, capable of executing all routine applications, including exams like CT angiography, where a 16-slice scanner is typically required. It is ideal for those clinicians who may want to add a second system to expand their clinical services in areas such as CTA. The Philips portfolio is also flexible. Their Brilliance iCT 128-slice platform also can be upgraded to 256-slice resolution as the needs of the facility change.

“Cardiologists want advanced applications that will allow them to respond more quickly and easily,” said Siemens’ DeGiorgio. “They want to acquire equipment that will be upgradeable for future advances. One can’t let someone go to the hospital with undiagnosed chess pains. CT can quickly resolve some of these diagnostic questions; it has that advantage.”

“Time is critical,” Banner said. “A big issue is radiation dose. Anything that can reduce the time of evaluation from 30 minutes to 5 minutes will be sought after.” For example, Siemens is introducing a CT scanner that will set new standards regarding speed and dose reduction. The system requires only a fraction of the radiation dose that systems previously required to scan even the tiniest anatomical details faster than ever before. The SOMATOM Definition Flash is a new dual-source CT, featuring two x-ray tubes that simultaneously revolve around the patient’s body. The fastest scanning speed in CT (ie, 43 cm/s) and a temporal resolution of 75 ms enable complete scans of the entire chest region in just 0.6 seconds. The short scan time means patients are no longer required to hold their breath during the exam the way they had in the past. At the same time, the SOMATOM Definition Flash operates at an extremely reduced radiation dose. For example, a spiral heart scan can be performed with less than 1 millisievert (mSv), whereas the average effective dose required for this purpose usually ranges from 8 mSv to 40 mSv.

In addition, according to Banner, the Siemens unit has the smallest footprint on the market so it doesn’t require a larger room for installation. The Philips iCT unit requires a room no larger than 365 square feet to install. This could be a significant factor in many purchase decisions.

Despite the advantages of CTA, according to the Cleveland Clinic Heart and Vascular Institute, these tests are not a substitute for other imaging techniques in all cardiovascular conditions. Unlike an echocardiogram machine, MRI and CT scanners cannot be brought to the bedside of an acutely ill patient. Nonetheless, cardiac MRI is already being used more and more as the examination of choice in certain settings (eg, assessment of myocardial viability). In addition, early success with noninvasive angiography of coronary arteries based on advanced cardiac CT techniques has led to its routine application in certain settings (eg, coronary artery bypass graft patient evaluation, detection of anomalous coronary arteries, and clarification of equivocal results from other screening exams for coronary disease). These tests have already become an integral part of the evaluation of patients with various forms of cardiovascular disease, and promising new versions continue to develop.

“Cardiologists want integrative solutions that allow physicians to scan at any heart rate,” Banner said. “The Siemens operating environment also allows cardiac physicians to access data wherever they are. This includes 4D on the Web. We provide Web-based, full-line software integration so cardiologists can read the heart and radiologists can read the chest when and where they need the information.”

For cardiac imaging—and cardiac patients—the overall picture is optimistic. According to the IMV survey, 39.1% of the survey respondents believe that the diagnostic and treatment efforts of the medical community will significantly reduce the incidence of hypertension within the next 10 years and 32.0% of these cardiologists expect the efforts of the medical community to significantly reduce the incidence of congestive heart failure (CHF) within the next 10 years. More than 75% of the IMV survey respondents believe that the diagnostic and treatment efforts of the cardiology and general medical community will actually reduce the incidence of new coronary artery disease (CAD) within the next 10 years.

James Markland is a contributing writer for Axis Imaging News.