Feasibility of [18F]-RGD for ex vivo imaging of atherosclerosis in detection of alpha v beta 3 integrin expression

Background. Inflammation and angiogenesis play an important role in atherosclerotic plaque rupture. Therefore, molecular imaging of these processes could be used for determination of rupture-prone atherosclerotic plaques. alpha v beta 3 integrin is involved in the process of angiogenesis. Targeted imaging of alpha v beta 3 integrin has been shown to be possible in previous studies on tumor models, using radiolabeled arginine-glycine-aspartate (RGD). Our aim was to investigate feasibility of ex vivo detection of alpha v beta 3 integrin in carotid endarterectomy (CEA) specimens.Methods and Results. Nineteen CEA specimens were incubated in 5 MBq [18F]-RGD-K5 for 1 hour followed by 1 hour emission microPET scan. The results were quantified in 4 mm wide segments as percent incubation dose per gram (%Inc/g). Segmental-to-total ratio was calculated and presence of alpha v beta 3 integrin and endothelial cells in each segment was confirmed by immunohistochemical staining for CD31 and alpha v beta 3 integrin, respectively. [18F]-RGD-K5 uptake was heterogeneously distributed across CEA specimens and was localized within the vessel wall. Significant correlations were observed between segmental-to-total ratio with alpha v beta 3 integrin staining score (r = 0.58, P = .038) and CD31 staining score (rho = 0.67, P <.002).Conclusion. This study showed the feasibility of integrin imaging by determination of alpha v beta 3 integrin expression in human atherosclerotic plaques.