Predicting unstable atheroma using FDG PET/CT and other nuclear tracers

Aim: To identify relationship between physiological properties and metabolism of carotid and aortic atheromatous plaques, and their level of 'stability' or likelihood of contributing to cardiovascular/ cerebrovascular events/ injury.
Method: Patients are scanned using ¹⁸F-FDG & ⁶⁸GA-DOTATATE/NOC PET CT to identify atheromatous plaques. Avid carotid plaque lesions are correlated with the appearances of the lesions on MRI. In patients that undergo endarterctomy, surgical samples undergo comprehensive histological analysis.

Previous Results: We have identified increased glucose metabolism in the wall of arotic aneurysms. We have identified an inverse trend between ¹⁸F-FDG uptake and aortic aneurysm expansion, therefore aneurysms with lower activity maybe less likely to expand. A positive relationship exists between plaque metabolism and markers of angiogenesis and inflammation, and an inverse relationship between plaque calcification and histologic markers of inflammation in aortic aneurysms.

Although at first glance results may seem contradictory, they serve to illustrate that physiology of aneurysm are complex, and that size of aneurysms does not predict likelihood of rupture/ stability.

Future directions: We are currently working to identify a relationship between histological markers and level of somatostatin receptor uptake in carotid artery aneurysms using ⁶⁸Ga -Dotatate. In future we intend to use various tracers to directly mark apoptosis, hypoxia and angiogenesis in vivo.