Cardiovascular CT stands both at a crossroads and directly in the crosshairs. Sixty-four slice and higher slice-count scanners are proving their prowess at creating exquisite images of the heart and coronary arteries, and clinical research and experience continue to demonstrate the clinical and economic value of cardiovascular CT. That’s because cardiovascular CT provides a non-invasive means to help physicians detect heart disease earlier, limit invasive cardiac catheterizations and save money compared to nuclear stress testing and catheterization. Plus, the newest scanners effectively reduce radiation dose.
On the downside, the cardiovascular CT community finds itself facing a formidable foe. The Centers for Medicare and Medicaid Services (CMS) has proposed adoption of a national coverage determination (NCD) that could substantially limit the use of CT angiography. If implemented, the policy would replace local coverage determination in all 50 states and the District of Columbia with an NCD that restricts coverage to narrow chest pain indications.
Despite the current regulatory ambiguity, cardiovascular CT remains a valuable option in the cardiac imaging arsenal. This month, a few experienced sites share their know-how.
Cardiovascular CT at a glance
Cardiovascular CT has evolved tremendously over the last few years. Take for example cardiovascular CT pioneer Fairfax Radiological Consultants in Fairfax, Va. The outpatient radiology group began offering cardiac CT in 2003 and recently invested in a new system: the GE Healthcare VCT XT, a next-generation 64-slice scanner. The new scanner offers a number of advantages over its predecessors, says Medical Director Jay Earls, MD.
“The VCT XT pairs improved speed with high-quality images at a much lower radiation dose than before. Five years ago, it took 20 seconds or longer to scan the heart, which presented problems for patients who couldn’t hold their breath for the duration of the scan. The average acquisition time on GE VCT XT is 4 seconds.”
Abbott Northwestern Hospital in Minneapolis is a relative newcomer to cardiac CT. The hospital deployed Siemens Medical Solutions Somatom Definition dual-source CT scanner in January 2007 and completed 2,300 scans last year.
“The scanner has changed cardiac imaging and patient care,” says John Lesser, MD, director of clinical cardiology. “Cardiologists are doing fewer normal invasive catheterizations.” That’s because physicians are ordering cardiac CT rather than an invasive cardiac catheterization when a patient has an equivocal stress test. If the CT is normal, the patient can bypass the cath lab. Cardiac CT also is the test of choice for cardiac patients who can’t tolerate the exercise required for a stress test.
Other sites, like Lenox Hill Heart and Vascular Institute in New York City, turn to CT as a cardiac and vascular imaging workhorse. The real question, says Harvey Hecht, MD, director of cardiovascular CT, is not which applications are appropriate for Philips Healthcare Brilliance 64-slice CT, but which aren’t.
Cardiovascular CT data provides crucial information, helping physicians determine if a patient’s symptoms are related to coronary artery blockage and to calculate the degree of blockage. Cardiovascular CT also provides information about plaque, so cardiologists can decide the optimal course to prevent rupture. “We use the scanner for a whole range of services. It’s the first test used to evaluate cardiac patients. A cardiac CT scan is superior to a traditional stress test for determining the appropriate therapy: angiography, stenting or bypass surgery. We also use the scanner to evaluate patients with equivocal stress tests and after cardiac catheterization to answer unresolved questions,” says Hecht. For example, the institute uses cardiac CT to evaluate coronaries not adequately visualized during cardiac catheterization because of damping of the catheter or inability to cannulate the artery. CT images also help physicians determine the course of anomalous vessels and delineate the occluded segment of a chronic total occlusion. Finally, physicians use CT images to size stents.
The reason behind the effectiveness of cardiovascular CT over conventional studies is quite simple. “Cardiac CT provides a 3D view of the coronary arteries. We can rotate the arteries on the post-processing workstation. Images acquired in the cath lab are more limited,” says Hecht. In fact, Hecht and his