New CT scanners are promising crystal-clear images of the heart in a single rotation, and 3D echocardiography is coming into its own as well. But just as these advances are being made, Medicare is threatening to eliminate reimbursement for coronary CT angiography (coronary CTA) unless it is part of an approved clinical trial, payors continue to reduce reimbursements for modalities regardless of their clinical gee-whiz capabilities, while the costs for these cutting-edge technologies are significantly more expensive than early generations. However, cardiac imaging experts are optimistic that having the latest and greatest will not only be a benefit to patients, but also reduce overall health care costs.
Cardiac Imaging Advances
Not long ago, having a 64-slice CT scanner was the envy of every cardiac imaging center caught with a brand-new 16 slice. These days, having a 64-slice CT is standard equipment for any dedicated hospital cardiac department or competitive outpatient imaging center.
One of 64 slice’s main advantages for cardiac imaging is its ability to perform coronary CTA studies with a 99% negative predictive value for coronary artery disease (CAD).1 From a cost perspective, payors, such as National Imaging Associates, Rancho Cordova, Calif, are currently evaluating whether the exam is effective and can be utilized as a cost-effective replacement for nuclear stress tests and reduce unnecessary cardiac catheterizations.2
Yet cardiac imaging specialists wanted even more out of their CT scanners—specifically, lower radiation doses and faster scan times to capture the heart, as well as perfusion studies. So it is perhaps not surprising that one’s recent 64-slice CT scanner may already be obsolete.
The annual meeting of the Radiological Society of North America saw the introduction of several future 64-slice killers. Among the most talked about for cardiac and other applications is the AquilionONE CT scanner from Toshiba Medical Systems, Tustin, Calif.
Robb Young, senior manager of CT at Toshiba, believes that the AquilionONE is a leap forward in multislice CT imaging because of its ability to scan an organ in one gantry rotation with 16 cm coverage.
Young explained, “It’s really the difference between looking at a still picture and a high-definition video. When you look at a 64 slice, regardless of its configuration, just to do multiple rotations around a patient’s organ, whether the heart or the brain, it can take up to 20 rotations to get enough data to get those 3D images. What’s really powerful about the AquilionONE is that you’re able to cover 16 cm in one gantry rotation.”
AquilionONE’s single gantry rotation also addresses reducing radiation exposure and CT contrast with its substantially abbreviated scan time. With 320 .5mm detector elements, Toshiba calls the AquilionONE a “dynamic volume” CT because it can capture an entire organ dynamically with just a couple of rotations, thus imaging blood flow as well as function and anatomy.
|The AquilionONE can image the entire heart in a single rotation, providing volumetric temporal resolution that is superior to multislice temporal resolution available today, resulting in clearer image quality.|
Young said, “You’re actually able to capture this whole organ for one moment in time, which opens the ability to very quickly not only assess the coronaries, but the entire myocardium.” Young also said that 16mm coverage can reduce radiation exposure over a multislice CT that may need 20 rotations to image a single organ. Instead, the AquilionONE’s single rotation captures the entire organ in one pass, eliminating the need to reconstruct slices from multiple points in time.
Of course, all of this imaging power comes at a premium that is significantly more than most $1.5 million 64-slice systems. Young said that the AquilionONE is priced at $2.5 to $2.8 million and concedes that a hospital would need to be buying it for more than just its cardiac department.
He said, “If you’re just talking cardiac, you can’t justify it. You have to look at all the other organ systems that you’re going to address. The AquilionONE can cover 16 cm, which not only includes the heart, but also can cover a brain or a kidney system.”
Tony DeFrance, MD, board certified in interventional cardiology, and medical director of CVCTA Education, San Francisco, believes that the AquilionONE still has the potential to reduce costs.
He said, “Since we have single rotation scanning and low dose, we can look at how the contrast is getting into the muscle and that’s really important, because right now we can see the anatomy, but often the question is how that is affecting blood flow. We can’t really assess that well with a 64, but with the 320, we’ll be able to look at the anatomy and perfusion, which—we’ll see in clinical practice—could potentially make this a one-stop shop. You could see anatomy, perfusion, and function, all in a 1- or 2-second study with low radiation doses.”
Young said that Toshiba is currently conducting validation studies with perfusion and the possible exams that could potentially be eliminated.
Another advanced CT that made an impact at RSNA this year was the 256 Slice Brilliance iCT from Philips Medical Systems, Bothell, Wash. With 256 detectors, fast acquisition speed, and 8 cm coverage, Philips says the Brilliance iCT is able to image the entire heart in two beats, while reducing radiation doses.
David Rosenblum, DO, vice chairman of the Department of Radiology at MetroHealth Medical Center in Cleveland, and Karen Kutoloski, DO, director of the hospital’s Women’s Health Center and director of cardiac rehabilitation, had the opportunity to test the Brilliance iCT before its official release.
Kutoloski said, “It helps imaging the coronaries because they’re a small structure. Also, previously [with a 64 slice] we had to slow the heart rate down to get better resolution. Now we can image faster. The heart rate’s still an issue, but it may not be quite as much of an issue.”
|The 256-slice Brilliance iCT scanner allows radiologists to produce high-quality images with exceptional acquisition speed, including complete coverage of the heart and brain.|
Rosenblum added, “We still administer beta blockers, but to give you an idea, if somebody’s heart rate is over 75 beats per minute, the spatial resolution in order to freeze the heart has to be under 100 milliseconds, and we are imaging now at about 150 milliseconds.”
A typical 64 slice might have a patient under the scanner for 12 seconds, but the 256 Brilliance iCT reduces that time to 5 to 8 seconds. That added speed can not only improve the image quality, but may also reduce radiation exposure time compared to a 64 slice.
According to a Philips press release, a retrospective study by the Wisconsin Heart Hospital found that it had achieved an 80% dose reduction using Philips’ “Step & Shoot” cardiac feature compared to previous exams using helical CT angiography techniques.
The Step & Shoot feature allows the scanner to focus the x-ray beam during a single phase of a particular cardiac cycle, such as late diastolic. Consequently, x-rays no longer need to be beamed throughout the entire cardiac cycle, thus reducing exposure time.
As to the larger price tag, Rosenblum commented, “If you’re a broad-based radiology practice or you want to dabble in cardiology, I probably wouldn’t go with the 256. I’d go with the 64 and you could probably do many applications and do OK. But if you’re high powered and you want to do a lot of cardiac vascular imaging, then you want to consider the extra cost. It will go a long way.”
3D Echocardiography Coming Into Its Own
Cardiac imaging has also seen advances in 3D echocardiography in the last several years, specifically on the use of transesophageal 3D echocardiography (TEE).
TEE miniaturizes all the technology required for acquisition of live rendered 3D echocardiographic images and essentially places them on the tip of a gastroscope.
Roberto Lang, MD, director of cardiac imaging and professor of medicine at the University of Chicago Medical Center, believes that the 3D system, though more expensive than traditional echocardiography, is a significant breakthrough for the preoperative planning of microvalve surgery.
He said, “I think it will also serve as a very important tool for the echocardiographic guidance of percutaneous procedures, such as percutaneous closure of an atrial septic defect or a PFO [patent foramen ovale], or for all the percutaneous procedures that are being geared toward reducing mitral regurgitation.”
Lang also believes that TEE will provide a new tool for the diagnosis of valvular heart disease, such as the diagnosis of malfunctioning prosthetic valves.
Like all advanced technology, the price of TEE is not cheap. Lang estimates that it can be in the ballpark of $300,000, which is a $100,000 premium over conventional echocardiography machines.
The second area of improvement in echocardiography is in “texture tracking,” sometimes referred to as “tissue tracking.” The technique uses a certain spectrum of the echocardiogram that is able to be tracked on a beat by beat, frame by frame, basis.
Lang said, “Texture tracking allows you to do the more automated quantification of ventricular function, which is very important, because based on that, the pumping ability of the heart, people decide on defibrillators.”
Though physicians may be able to use technology such as TEE to make a better diagnosis and perhaps prevent unneeded further testing, Medicare and payors will not reimburse physicians for the same exam that could have been performed with a traditional machine. The same is true for advanced CT technology, which is increasingly under reduced reimbursement pressures.
CMS Targets Cardiac CTA
Whether hospitals and cardiac-focused imaging centers buy that multimillion-dollar advanced 256-slice CT or even a 64-slice CT, reimbursement cost pressures are still hitting radiology from the 2005 Deficit Reduction Act (DRA). Recently, Medicare delivered another blow to already tight capital budgets.
Currently, all 50 states allow for reimbursement for coronary CTA, but if CMS has its way, coronary CTA will be reimbursable only if the exam is part of a clinical trial approved by CMS and is performed on symptomatic patients with either chronic stable angina at intermediate risk for coronary artery disease or unstable angina at low to intermediate risk of CAD.
|Cardiac imaging is more sophisticated and promising than ever before. The Brilliance iCT from Philips is able to image the entire heart in two beats, while reducing radiation dose.|
The public comment period ended in mid-January of this year with a final decision to be announced on March 13.
Physicians argue that coronary CTA’s widely accepted 99% negative predictive value1 is a useful imaging test, especially in emergency departments that evaluate chest pain. But CMS and private payors are concerned about overutilization and that coronary CTA is simply redundant and less useful than a nuclear stress test.
DeFrance, who teaches how to do coronary CTA and other advanced imaging techniques, strongly believes that CMS should reconsider its proposal. He said, “By throwing [coronary CTA] out or by drastically limiting it, they’re throwing the baby out with the bath water. They want to limit imaging in general, but we finally have a test that looks promising for reducing costs. So this is not the right test to eliminate.”
DeFrance listed 12 studies encompassing 1,271 patients that have demonstrated the effectiveness of multislice cardiac angiography for the diagnosis of acute chest pain. These include a randomized controlled study showing a 77% reduction in diagnostic time and a 16% reduction in the cost of care compared to standard diagnostic evaluation.3-13
If Medicare does cut coronary CTA reimbursement, DeFrance suspects that while it may affect the coronary CTA field, it would not stop its growth. “I think this is a speed bump, because this technology is so compelling, patients like it so much, and it has such good and growing data behind it that it may slow it temporarily, but it’s not going to go away.”
- Hoffmann MH, Shi H, Schmitz BL, et al. Noninvasive coronary angiography with multislice computed tomography. JAMA. 2005;293:2471-2478. jama.ama-assn.org/cgi/content/abstract/293/20/2471. Accessed January 29, 2008.
- NIA/Magellan to begin pilot program for coronary CTA patient handling protocols. www.imagingeconomics.com/issues/articles/2006-10_04.asp#4.
- Sato Y, Matsumoto N, Ichikawa M, et al. Efficacy of multislice computed tomography for the detection of acute coronary syndrome in the emergency department. Circ J. 2005;69:1047–1051.
- White CS, Kuo D, Kelemen M, et al. Chest pain evaluation in the emergency department: can MDCT provide a comprehensive evaluation? AJR Am J Roentgenol. 2005;185:533–540.
- Hoffmann U, Penal AJ, Ferencik M, et al. MDCT in early triage of patients with acute chest pain. AJR Am J Roentgenol. 2006;187:1240–1247
- Hoffmann U, Nagurney JT, Moselewski F, et al. Coronary multidetector computed tomography in the assessment of patients with acute chest pain. Circulation. 2006;114:2251–2260.
- Gallagher MJ, Ross MA, Raff GL, et al. The diagnostic accuracy of 64-slice computed tomography coronary angiography compared with stress nuclear imaging in emergency department low-risk chest pain patients. Ann Emerg Med. 2007;49:125–136.
- Rubinshtein R, Halon DA, Gaspar T, et al. Usefulness of 64-slice cardiac computed tomographic angiography for diagnosing acute coronary syndromes and predicting clinical outcome in emergency department patients with chest pain of uncertain origin. Circulation. 2007;115:1762–1768.
- Hollander JE, Litt HI, Chase M, et al. Computed tomography coronary angiography for rapid disposition of low-risk emergency department patients with chest pain syndromes. Acad Emerg Med. 2007;14:112-116
- Johnson TRC, Nikolaou K, Wintersperger BJ, et al. ECG-gated 64-MDCT angiography in the differential diagnosis of acute chest pain. AJR Am J Roentgenol. 2007;188:76-82
- Goldstein JA, Gallagher MJ, O’Neill WW, et al. A randomized controlled trial of multi-slice coronary computed tomography for evaluation of acute chest pain patients. J Am Coll Cardiol. 2007;49:863–871.
- Vrachliotis TG, Bis KG, Haidary A, et al. Atypical chest pain: coronary, aortic, and pulmonary vasculature enhancement at biphasic single injection 64-section CT angiography. Radiology. 2007;243:368–376.
- Onuma Y, Tanabe K, Nakazawa G, et al. Non cardiac findings in cardiac imaging with multidetector computed tomography. J Am Coll Cardiol. 2006;48:402–406.
Tor Valenza is a staff writer for Axis Imaging News. For more information, contact .