New research published in this week’s New England Journal of Medicine reveals that noninvasive CT scans are nearly as accurate at imaging coronary artery blockages as conventional angiography and are much safer for many patients.

An angiography requires inserting a slim catheter tube into an artery in the groin and running it up into the arteries near the heart. The procedure usually takes 30 to 45 minutes plus another hour of recovery; complications, though rare, include heart attack and stroke.

Researchers at Johns Hopkins University in Baltimore discovered that the new expensive CT scans can detect narrowed blood vessels in people with suspected heart disease nearly as well as the conventional angiogram. More exactly, they found that so-called 64-row computed tomography, or CT scans were 93 percent as precise as conventional cardiac catheterization without subjecting a patient to an invasive procedure. The only downside is that the patients are exposed to relatively high levels of radiation. A 2007 study linked up to 2 percent of all US cancers to CT radiation.

For the study, Dr. Julie Miller, an interventional cardiologist at Johns Hopkins University School of Medicine in Baltimore and colleagues at nine hospitals in the United States, Canada, Germany, Japan, Brazil, Singapore and the Netherlands identified 291 patients with symptoms of coronary artery disease who were candidates for traditional angiograms. Their median age was 59, and 74 percent of them were men.

The researchers used a 64-slice CT scanner made by Toshiba Medical Systems, which funded the study along with the National Institutes of Health and private foundations. Then the participants underwent conventional angiograms.

In 163 patients with the highest degree of coronary artery disease, the CT angiograms were 93 percent as good as the traditional angiograms, the study showed. Overall, the CT scans accurately identified 85 percent of the patients who had the biggest blockages and 90 percent of the patients who did not.

Also, the researchers found that 91 percent of patients who were identified by the CT scans as having the most severe disease were correctly diagnosed, as were 83 percent of patients whose scans did not reveal large blockages.

Although some argue that the new CT scans might not be as good as angiograms, “our study shows they do have value, because they have a high degree of diagnostic accuracy to identify patients with tight heart blockages. Having the scan is a noninvasive procedure, and that is very attractive. Patients do not undergo the risk, even though it is small, of angiography,” Dr. Miller said.

However, the study concluded that scanners “cannot replace conventional coronary angiography at present.”

According to the American Heart Association, more than 1.2 million patients in the US undergo cardiac angiograms each year and 1 percent to 2 percent of those cases result in complications. The National Center for Health Statistics at the Centers for Disease Control and Prevention estimates that 25 people die every year as a result of the procedure.