Feasibility of [18F]-RGD for ex vivo imaging of atherosclerosis in detection of αvß3 integrin expression.

ABSTRACT

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. αvß3 integrin is involved in the process of angiogenesis. Targeted imaging of αvß3 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 αvß3 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 αvß3 integrin and endothelial cells in each segment was confirmed by immunohistochemical staining for CD31 and αvß3 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 αvß3 integrin staining score (r = 0.58, P = .038) and CD31 staining score (ρ = 0.67, P < .002). CONCLUSION: This study showed the feasibility of integrin imaging by determination of αvß3 integrin expression in human atherosclerotic plaques.