Scanning the Horizon of Cardiac Imaging

February 2006 Special Advertising Section  

Chest pain or a heart attack used to be the first sign of clogged arteries, and by then it was often too late to intervene. But advances in cardiac imaging are changing that. New heart scanning technology can detect early calcified plaque in the arteries before it leads to a life-threatening condition.

Geoffrey Bodeau, a radiologist with Consulting Radiologists, Ltd. in Minneapolis, and codirector of HeartScan Minnesota at Minneapolis’ Abbott Northwestern Hospital, says early cardiac imaging and the gradual shift in medicine from a treatment emphasis to a preventive one can save lives. “Up until several years ago, the way that medicine was practiced was that we waited until someone was sick, and we treated them the best way possible,” he says.

Today, the most advanced computed tomography (CT) scanners can take remarkably clear photos of the entire heart in six to eight seconds—one breath hold—to reveal early atherosclerosis (narrowing of the arteries). Magnetic resonance imaging (MRI) can take beautiful pictures that show whether heart muscle is dead or alive. Technological breakthroughs have also pushed traditional stress testing and catheterization to new heights in accuracy and efficiency.

There’s no question that cardiac imaging has come a long way in identifying narrowed or blocked arteries, which can lead to a heart attack or stroke. But a consensus on how these diagnostic tools are best used is still awaiting the accumulation of convincing evidence.

Views on CT Scanning
Cardiologists agree the multi-slice CT, an anatomical test, is a tremendous advance in screening over conventional catheterization in that it is a noninvasive and less risky way to identify atherosclerosis in the coronary arteries. “What’s so nice about it is that you can pick up very early plaquing, which can start in the twenties,” says Gregory Helmer, a cardiologist at the Minnesota Heart Clinic and director of non-invasive cardiovascular services at Fairview Southdale Hospital in Edina. Catching it earlier means the opportunity to treat sooner and more aggressively, even in patients with no symptoms, he says.

Anyone who is concerned that they or a loved one may have atherosclerosis because they have risk factors for heart disease can undergo calcium scoring, a sensitive test done with an advanced CT scanner that can pick up early atherosclerosis, Bodeau says. A physician referral is not necessary, but anyone who has the test is urged to discuss the results with their doctor, Bodeau says.

The faster the CT, the safer it is, because less medication is required to slow the heart to a speed at which it can be photographed without motion artifact, says Don Johanns, director of medical imaging at United Hospital in St. Paul. “The heart rate needs to be very stable,” he says. “We need to administer drugs to slow the heart down, and if the patient is having a heart attack or cardiac perfusion, that can be risky.”

Bradley Bart, director of nuclear cardiology at Hennepin County Medical Center in Minneapolis and an assistant professor of medicine at the University of Minnesota, says CT scanning may potentially have a role in, for example, deciding whether to start a cholesterol-lowering medication in someone with borderline high cholesterol. But he isn’t convinced it’s a valuable general screening tool, because there isn’t overriding evidence that it results in better outcomes. “It doesn’t really tell you how the heart is working or whether symptoms are related to the anatomy that you’re seeing,” he says. “I tend to take a very pragmatic approach to these imaging studies; the question is, what are you going to do with that information?”

Bart says there are only three possible courses of action if you find evidence of significant atherosclerosis: lifestyle changes, medications, or cardiac revascularization (heart bypass or stent placement). We all know, Bart says, that we should exercise regularly, not smoke, maintain a healthy weight, and follow a good diet. “Did you really need a scan to tell you that you should be doing those things?” he asks.