Assessment of avb3 integrin expression after myocardial infarction by positron emission tomography

Aims The purpose of this study was to determine the feasibility of a new positron emission tomography (PET) imaging approach using an 18F-labelled avb3 integrin antagonist ( 18F-Galacto-RGD) to monitor the integrin expression after myocardial infarction. Methods and results Male Wister rats were subjected to 20 min transient left coronary artery occlusion followed by reperfusion. Autoradiographic analysis and in vivo PET imaging were used to determine myocardial 18F-Galacto-RGD uptake at different time points following reperfusion. Results PET imaging and autoradiography demonstrated no significant focal myocardial 18F-Galacto-RGD uptake in non-operated control rats and at day 1 after reperfusion. However, focal accumulation in the infarct area started at day 3 (uptake ratio 1.91+0.22 vs. remote myocardium), peaked between 1 (3.43+0.57) and 3 weeks (3.43+0.95), and decreased to 1.96+0.40 at 6 months after reperfusion. Pretreatment with avb3 integrin antagonist c(-RGDfV-) significantly decreased tracer uptake, indicating the specificity of tracer uptake. The time course of focal tracer uptake paralleled vascular density as measured by CD31 immunohistochemical analysis. Conclusion Regional 18F-Galacto-RGD accumulation suggests up-regulation of avb3 integrin expressio