Molecular imaging in atherosclerosis: FDG PET

Abstract

18F-FDG PET is a new noninvasive tool for inflammation functional imaging. Low spatial resolution is now compensated by coregistration with CT or MRI. New mechanistic insights have emerged from animal and histology to explain the obtained signals by hypoxia, macrophage infiltration, and differentiation. Mixed results have been found in biomarkers studies. Interesting data have come recently linking plaque anatomy and function in carotids and in aortic aneurysms as well as inflammation and events. In coronary arteries, plaque assessment is still hampered by myocardium uptake but developments are being made. 18-FDG PET has been able to monitor inflammation before and after several therapies in animals and humans but to date the lack of standardization and the absence of prospective event-driven studies prevent this promising technique to be used in clinical practice.

Fig. 1

Sample MRI images from a patient at baseline top) and treated with dalcetrapib 600 mg for 24 months (bottom) showing regression in total vessel area (top panel). The MRI metrics used as endpoints are shown in the bottom panel. LCC = left carotid artery. RCC = right carotid artery. Wall outer boundary is denoted in green. Wall inner boundary is denoted in yellow. Total vessel area is lumen area + wall area. Normalized wall index is wall area divided by total vessel area and represents a ratio with no units