There are few reliable methods that can be used to identify inflamed plaque non-invasively before they rupture. Instead, physicians have relied on detection of blood vessel narrowing to predict which patients are at risk for strokes. However, blood vessel narrowing is a relatively poor predictor of stroke risk; most patients with severe carotid artery narrowing remain stroke-free for over 5 years without treatment, although surgery or medication may be employed when significant carotid plaque is found. Therefore, Dr. Ahmed Tawakol, MD, and his team sought a new means of characterizing carotid plaque. The researchers delivered their findings on June 22 at the Society of Nuclear Medicine's 51st Annual Meeting in Philadelphia.
For the study, the scientists studied ten patients with moderate to high-grade carotid stenoses (the narrowing of the carotid artery that can lead to stroke) to test their hypothesis that carotid plaque inflammation can be characterized non-invasively using PET with 18F-FDG (glucose labeled with a radioactive isotope of fluorine) as the imaging agent.
Within one month of PET imaging, the same patients underwent carotid endarterectomy (the surgical removal of plaque from the carotid artery), at which time their carotid plaque specimens were collected and inflammation was determined using immunohistological methods. The results revealed a correlation between FDG uptake, as measured by PET, and degree of plaque inflammation. Although the work is still in preliminary stages, the hope is that eventually FDG-PET imaging could be used to improve the prediction of stroke risk.
This is the first time FDG-PET imaging has been used to provide an index of vascular inflammation in human subjects," according to Dr. Tawakol. "The potential applications of the study are numerous. Obviously, early detection and better characterization of carotid plaque could enhance our ability to combat stroke. We also anticipate that the FDG-PET method could be used to test plaque-stabilizing drugs. Moreover, we hope that a similar method might be developed to detect coronary artery disease in the future."
The Society of Nuclear Medicine is holding its 51st Annual Meeting June 19–23, 2004, at the Pennsylvania Convention Center in downtown Philadelphia. Hot topics for the 2004 meeting include techniques for the early diagnosis of Alzheimer's disease; advanced imaging for the diagnosis, staging, and treatment of cancer; nuclear cardiology; and the collaboration between nuclear medicine and bioengineering in the fight against cancer.