Salt in the wound: (18)F-fluoride positron emission tomography for identification of vulnerable coronary plaques

Ischaemic vascular events occur in relation to an underlying vulnerable plaque. The pathological hallmarks of high-risk plaques are well described and include inflammation and microcalcification. To date, non-invasive imaging modalities have lacked the spatial resolution to detect these processes with the necessary precision to facilitate clinical utility. Positron emission tomography (PET) using targeted radiopharmaceuticals affords a highly sensitive tool for identifying features of interest and has been in use for several decades in oncological practice. Recent developments have created hybrid scanning platforms which add the detailed spatial resolution of computed tomography (CT) and, for the first time, made imaging of individual coronary plaques feasible. In this study we compared the utility of PET-CT using (18)F-fluoride and (18)F-fluorodeoxglucose ((18)F-FDG) to detect high-risk or ruptured atherosclerotic plaques in vivo. (18)F-fluoride localized to culprit and vulnerable plaques as determined by a combination of invasive imaging and histological tissue examination. In contradistinction, (18)F-FDG analysis was compromised by non-specific myocardial uptake that obscured the coronary arteries. We discuss the findings of this study, the limitations of the current approach of vulnerable plaque assessment and some on-going developments in cardiovascular imaging with (18)F-fluoride.