Jun 5 2007
The use of combined imaging technologies may hold the key to stopping and even preventing heart attacks, according to research reported at the 54th Annual Meeting of SNM, the world's largest society for molecular imaging and nuclear medicine professionals.
"For the first time, we have shown that we can detect dangerous, high-risk plaque that causes heart attacks and strokes through the use of multidetector computed tomography (CT) imaging and a novel contrast agent," said James H. Rudd, a cardiologist and scientist with the Imaging Sciences Laboratory at Mount Sinai School of Medicine in New York City. Additionally, researchers combined CT imaging with positron emission tomography (PET) imaging, "providing a new way to determine the amount of inflammation within atherosclerotic plaque and the chances of plaque causing a future heart attack or stroke," he noted.
The slow, progressive buildup of fats, cholesterol and other substances,called plaque,on the inner lining of arteries causes atherosclerosis, which can lead to heart disease. Plaques can narrow the heart's arteries, allowing less blood to flow to the heart muscle (causing angina), and plaques that rupture may cause sudden heart attack, stroke or death. Nearly 80 million Americans have one or more forms of cardiovascular disease.
"Using both imaging techniques together,an excellent example of multimodality molecular imaging,gave more information than using them separately," explained Rudd. "Each technique tells us something different about atherosclerosis," he said. With CT imaging and N1177 (a nanoparticulate contrast agent used to improve the effectiveness of CT and provided by NanoScan Imaging LLC), researchers "were able to determine the size of plaque, whether it was causing narrowing of the arteries and whether any inflammatory cells were involved," said Rudd. "From the PET scan, we got extra information about whether the plaques were dangerous and whether they could lead to problems for patients," he added. The combined imaging techniques focused "not only on the structure of plaque but also on the underlying molecular biology of the disease in the hope of guiding and monitoring future therapies," said Rudd.
PET is a highly specialized, noninvasive imaging technique that uses short-lived radioactive substances to produce three-dimensional color images of those substances functioning within the body. Unlike CT, which provides anatomic images, PET scanning provides information about the body's chemistry, metabolic activity and function not available through other procedures.
Rudd explained that the Mount Sinai study was performed using an animal model of atherosclerosis that "behaves" like the disease in humans. Additional research needs to be done with heart disease and stroke patients "to see if our approach gives more information than the traditionally used technique of invasive X-ray coronary angiography," he said. Rudd, who also holds a position at the Division of Cardiovascular Medicine in Cambridge, United Kingdom, said that part of the work at Mount Sinai was funded by the British Heart Foundation, a charity that supports research and education about heart disease.
"This work features the enhanced imaging of atherosclerotic plaques,using a novel combination of technologies," said Josef Machac, SNM's Scientific Program Committee cardiovascular vice chair. "FDG-PET has been demonstrated to be taken up in macrophage-rich plaques, indicating an inflammatory component of atherosclerosis," added the director of nuclear medicine at the Mount Sinai School of Medicine in New York City.