Assessment of atherosclerosis in large vessel walls: A comprehensive review of FDG-PET/CT image acquisition protocols and methods for uptake quantification

Abstract

There is growing evidence showing the importance of fluorodeoxyglucose positron emission tomography (FDG-PET) in the evaluation of vessel wall inflammation and atherosclerosis. Although this imaging modality has been increasingly used, there are various methods for image acquisition and evaluating FDG uptake activity in the vessel walls and atherosclerotic lesions, including qualitative visual scaling, semi-quantitative, and quantitative evaluations. Using each of these image acquisition protocols and measurement methods may result in different findings. In this review, we are going to describe the various image acquisition methods and common measurement strategies reflected in the literature and discuss their advantages and flaws.

Optimizing FDG-PET/CT imaging of inflammation in atherosclerosis

“…Optimal circulation time of 18F-FDG for arterial imaging may be longer than 90 minutes, but authors note that more comparative studies are needed to define it. [9][10][11] Similarly, even moderate hyperglycaemia can lower 18F-FDG uptake by plaque cells. 10 This is probably mainly based on competition between glucose and 18F-FDG as metabolic substrates and more tracer remains in circulation.…”

“…9 They note that high 18F-FDG dose is not necessary to obtain sufficient image quality and accurate lesion quantification that is important to optimize the radiation dose to the patient. In contrast, timing of imaging after tracer injection has significant effect on arterial 18F-FDG signal.…”

“…Different approaches have been applied for measurement of arterial 18F-FDG uptake in different studies as described by Gholami et al 9 18F-FDG uptake values from multiple sections can be averaged within an entire artery or arteries. This can offer an accurate estimate of overall plaque activity and may be best suited for monitoring the response to systemic treat-ments for atherosclerosis.…”

“…A source of variation is that a generally accepted vesselspecific threshold for abnormal 18F-FDG signal in atherosclerosis has not been defined yet. 9 Relatively small studies with methodological differences have compared in vivo 18F-FDG signal with the histological basis of 18F-FDG uptake in atherosclerotic plaques. 13 Furthermore, it may be that 18F-FDG uptake is present only transiently during the natural course of atherosclerotic plaque development.…”

Editorial in response to: PET/CT evaluation of 18F-FDG uptake in pericoronary adipose tissue in patients with stable coronary artery disease: Independent predictor of atherosclerotic lesion formation?

“…While FDG imaging has shown promise in imaging atherosclerotic plaques in carotid arteries, technical issues arise when imaging coronary arteries. As Gholami et al 12 recently reviewed, methodologies for prescan patient preparation (fasting, blood glucose levels) and optimal imaging time post-FDG injection can all preclude the quality and reproducibility of results by affecting the target-to-background ratio.…”