Physicians may soon gain a new tool to enable them to diagnose patients at risk of heart attacks with far more accuracy than is now possible, a researcher reported Monday in Chicago at the opening session of the world's biggest radiology meeting.
The new technology allows doctors to look at the lining of coronary arteries with enough clarity to help them determine which vessels are likely to rupture and leak fat into the blood, causing clots that will trigger a heart attack, said Zahi Fayad, an assistant radiology professor at Mt. Sinai School of Medicine in New York.
"For the first time, we are able to look inside the vessel wall and see what is in there," said Fayad, who presented his findings to the Radiological Society of North America at its annual meeting being held in McCormick Place.
The standard technique for diagnosing coronary artery disease--coronary angiography--fails to find most of the truly dangerous artery disease, said Fayad.
Angiography uses a thin tube placed inside a coronary artery that is filled with contrast solution. The solution is squirted out of the tube so X-ray images may be made to show any spots where the artery lining has grown so thick with plaque it narrows the space available for blood flow. When an artery becomes blocked and blood cannot flow at all, heart tissue starves and dies, resulting in a heart attack.
The problem, said Fayad, is that only certain types of plaque in artery walls are unstable. Research suggests that these risky plaques appear normal on angiogram X-rays nearly 70 percent of the time.
"What makes artery plaque dangerous is if it has a big pool of fat accumulated that can rupture into the blood where it will form clots," Fayad said.
Researchers at Mt. Sinai, working with General Electric's medical imaging division, have demonstrated they can make images that detail the content of plaque, Fayad said. They use magnetic resonance imaging, a technology widely used to diagnose brain tumors and other afflictions but which has had little application in coronary disease.
GE has designed MRI equipment especially intended to make images of the beating heart, and Mt. Sinai researchers have collaborated in writing software to produce coronary artery images. Other equipment makers also are building special coronary imaging devices, he said.
Though the pilot study included only a handful of patients with artery disease as well as several healthy college students, Fayad said the images produced were sufficient to spot risky plaque in one patient who was referred for treatment.
More extensive MRI coronary artery studies are now under way, Fayad said, and Mt. Sinai researchers hope they will establish the efficacy of this technology in diagnosing artery disease.
Unlike angiography or another new technology called intravascular ultrasound, MRI doesn't require putting anything inside the patient's body. MRI requires only that the patient lie in a strong magnetic field while radio waves bombard the body to create images of arteries.
"This could change the face of cardiology imaging," Fayad said.
If the studies now being done work out as hoped, MRI exams for coronary patients could become common within a few years, he said.
"MRI also might be used to see if treatment is working, and to help determine whether other measures need to be taken," Fayad said. "It also may tell us when the plaque is stable, and that perhaps in some cases no therapy is needed."