Positron Emission Tomography and Dynamic Contrast- Enhanced MRI in Carotid Atherosclerosis Implications for Plaque Inflammation

The fundamental role of inflammation in atherosclerosis is well established through animal and autopsy studies, which has promoted the development of imaging approaches for in vivo assessment of plaque inflammation. Among many biological targets implicated in plaque inflammation, macrophages and neovessels have gained broad interest because they are abundant and detectable by clinical imaging modalities such as F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and dynamic contrast-enhanced (DCE) MRI. Increased metabolic activity measured as target-to-background ratio (TBR) is thought to indicate enhanced macrophage recruitment and activation. In contrast, the transfer constant (K) in DCE-MRI is considered to reflect microvessel density and permeability. As 2 integral components of the inflammatory process, previous studies have suggested that cellular events, including macrophage recruitment and activation, and vascular adaptation, including angiogenesis and increased permeability, could affect each other during atherogenesis. We studied their relationship using in vivo imaging.