Molecular imaging provides a better way to visualize heart disease

Jun 5 2007

Technically advanced molecular imaging provides a 3-D way to significantly improve the diagnosis of heart disease, according to researchers at the 54th Annual Meeting of SNM, the world's largest molecular imaging and nuclear medicine society.

"The exciting results of our study show that physicians can use our technologically advanced fusion of anatomic and physiological three-dimensional color displays to significantly improve the accuracy of diagnosing heart disease," said Cesar A. Santana, assistant professor of radiology at the Emory School of Medicine in Atlanta, Ga. "In addition, these computer fusion and rendering techniques could be used in the future with molecular imaging agents to detect and guide the treatment associated with coronary artery disease," he added.

"Using innovative new computer techniques, we took images of the coronary arteries from one study, called a computed tomography (CT) angiography, and superimposed them on top of images of heart muscle," he noted. "The heart muscle was color coded to the blood flow brought in by the coronaries into the muscle. That blood flow information was obtained from a nuclear imaging scan," he further explained.

Coronary artery disease (CAD), the most common form of heart disease, occurs when the arteries that supply blood to the heart muscle become hardened and narrowed, explained Santana. The arteries harden and narrow due to buildup of a material called plaque on their inner walls. As the plaque increases in size, the insides of the coronary arteries get narrower and less blood can flow through them. Over time, blood flow to the heart muscle is reduced, and, because blood carries much-needed oxygen, the heart muscle is not able to receive the amount of oxygen it needs. About 7 million Americans suffer from coronary heart disease, and nearly 500,000 will die from it annually.

The study's results were obtained using several cutting-edge technologies: CT to view the coronary arteries; nuclear imaging [positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging processes)] to view the blood flow to the heart muscle; and an innovative computer technique to combine and display these two types of information. A CT angiography scan is an X-ray procedure that produces detailed cross-sectional images of the coronary arteries. PET and SPECT are highly specialized, noninvasive imaging techniques that use short-lived radioactive substances to produce three-dimensional images that reveal information about blood flow and function of the heart.

"Our results are the culmination of more than 15 years of research and development by our Emory nuclear cardiology research scientists and physicians," said Santana. He credited both Tracy L. Faber, associate professor of radiology, and Ernest V. Garcia, radiology professor and head of Emory's Nuclear Cardiology Research and Development Lab.

"There still is considerable more work needed to improve the accuracy of the superimposition of the coronary tree onto the heart muscle and to improve the rendering method of displaying the images so that the right information is conveyed to the physician," said Santana.

"This work illustrates the value of a coregistered, combined 3-D display of blood flow together with CT angiography imaging data," noted Josef Machac, SNM's Scientific Program Committee cardiovascular vice chair. "This information, taken together, demonstrates superior performance, compared to each modality alone. This has been speculated on, but now, we have empirical evidence that it is true," added the director of nuclear medicine at the Mount Sinai School of Medicine in New York City.