PET/CT offers ’superior’ view of atherosclerosis plaque, may identify those at risk for heart attack

Positron emission tomography (PET) in combination with computed tomography (CT) offers a “superior” view of atherosclerosis plaque inflammation—so much so that it may eventually be used to identify individuals who are at high risk for heart attack or stroke, according to researchers at Massachusetts General Hospital in Boston. Their findings were released during SNM’s 53rd Annual Meeting June 3–7 in San Diego.

“The future is using PET/CT—and other developing technologies—to assess plaques that are biologically active with deadly consequences when they misbehave,” said Ahmed Tawakol, cardiologist and co-director of the Cardiac MR/PET/CT Program at Massachusetts General Hospital. “PET/CT in combination is more powerful than either PET or CT alone, providing us with an enriched data set,” added the co-author of “Combined PET/CT Assessment of Carotid Plaques: A Human Histopathological Study.” He explained, “In investigating the use of today’s imaging technologies to predict those individuals with high risk for stroke or heart attack, we determined we can possibly improve on current risk stratification strategies by identifying patients as being at low, moderate, high or very high risk for developing a heart attack or stroke.” PET/CT “may allow us to identify patients at highest risk for heart attacks or strokes, so physicians can focus the appropriate medical attention on them more quickly and more aggressively,” said Tawakol. In addition, it “might allow us to reclassify individuals previously thought to be at high risk. Biologically inactive plaques suggest a moderate or even low risk, thereby sparing patients more aggressive interventions,” he added.

Atherosclerosis is the process in which deposits of fats, cholesterol, cellular waste products and other substances—called plaque—build up in the inner lining of an artery. This may limit blood flow through the carotid arteries, which supply blood to the head and neck. More than 71 million Americans have one or more forms of cardiovascular disease, which claims more lives than cancer, accidents and HIV (AIDS) combined.

This study benefits those individuals with carotid disease and opens the exploration of the biological questions of atherosclerosis and related heart diseases, said Tawakol. “This molecular imaging research opens the door for the testing of new and future therapies and the identification of promising new drugs,” he added.

PET/CT imaging enables the collection of both biological and anatomical information during a single exam, with PET picking up metabolic signals of body cells and tissues and CT offering a detailed picture of internal anatomy. “We establish that PET in combination with CT is superior to PET alone for characterization of plaque inflammation,” said Tawakol, explaining that the current study builds on prior observations that PET is useful in characterizing plaque formation. “There is a lot of interest in learning how to stabilize or pacify plaques, and we may be able to test this,” he noted, saying additional research might determine if a cardiac event can be predicted by identifying plaque inflammation.

“This is very exciting work,” said Josef Machac, SNM’s Scientific Program Committee cardiovascular vice chair. “The idea is that atherosclerosis comes in different ‘flavors,’ and the challenge is to predict whether patients are at high risk for having a stroke or heart attack,” added the director of the Clinical PET Center and nuclear medicine at Mount Sinai School of Medicine in New York City. He continued, “This research points the way by examining carotid plaque function from PET and its structure from CT.”

Abstract: A. Tawakol, D. Vermylen, J. Swanson and J. Moloo, medicine/cardiology, Massachusetts General Hospital, Boston; R. Curry, A. Morss, U. Hoffmann, T.J. Brady and A.J. Fischman, radiology, Massachusetts General Hospital, Boston; and S. Bedri, pathology, Massachusetts General Hospital, Boston, “Combined PET/CT Assessment of Carotid Plaques: A Human Histopathological Study,” SNM’s 53rd Annual Meeting, June 3–7, 2006, Scientific Paper 9.

About SNM

SNM is holding its 53rd Annual Meeting June 3–7 at the San Diego Convention Center. Research topics for the 2006 meeting include molecular imaging in clinical practice in the fight against cancer; the role of diagnostic imaging in the management of metastatic bone disease; metabolic imaging for heart disease; neuroendocrine and brain imaging; new agents for imaging infection and inflammation; and an examination of dementia, neurodegeneration, movement disorders and thyroid cancer.

SNM is an international scientific and professional organization of more than 16,000 members dedicated to promoting the science, technology and practical applications of molecular and nuclear imaging to diagnose, manage and treat diseases in women, men and children. Founded more than 50 years ago, SNM continues to provide essential resources for health care practitioners and patients; publish the most prominent peer-reviewed resource in the field; sponsor research grants, fellowships and awards; host the premier annual meeting for medical imaging; and train physicians, technologists, scientists, physicists, chemists and radiopharmacists in state-of-the-art imaging procedures and advances. SNM members have introduced—and continue to explore—biological and technological innovations in medicine that noninvasively investigate the molecular basis of diseases, benefiting countless generations of patients. SNM is based in Reston, Va.; additional information can be found online at www.snm.org.