A Clinical Role of PET in Atherosclerosis and Vulnerable Plaques?

Abstract

Atherosclerosis is a chronic and most often progressive disease with a long clinically apparently silent period, and can become unstable at any time, due to a plaque rupture or erosion, leading to an acute atherothrombotic event. Atherosclerosis has a progression rate that is highly variable among patients and in the same patient. The progression of atherosclerotic plaque from asymptomatic to symptomatic phase depends on its structure and composition in which inflammation plays an essential role. Prototype of the ruptured plaque contains a large, soft, lipid-rich necrotic core with intraplaque hemorrhage that accounts for more than half of the volume of the plaque covered by a thin and inflamed fibrous cap with few smooth muscle cells, and a heavy infiltrate of inflammatory cells. Noninvasive imaging modalities might provide an assessment of the atherosclerotic disease process through the exploration of these plaque features. Computed tomography angiography and magnetic resonance imaging can characterize plaque morphology, whereas molecular imaging, owing to the high sensitivity of nuclear medicine for the detection of radiopharmaceuticals in tissues, allows to explore plaque biology. During the last 2 decades, FDG-PET imaging has also emerged as a powerful tool to explore noninvasively inflammatory activities in atherosclerotic plaques providing new insights on the evolution of metabolic activities in the vascular wall over time. This review highlights the role of PET imaging for the exploration of metabolic activities in atherosclerotic plaques. It will resume the evidence that have been gathered from clinical studies using FDG-PET and will discuss the perspectives of new radiopharmaceuticals for vulnerable plaque imaging.