Abstract 1143: Imaging of Vasa Vasorum in Atherosclerotic Plaque with 99m Tc-labeled single chain-VEGF

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Introduction: Adventitial vasa vasorum proliferation and neointimal neovascularization are associated with intraplaque hemorrhage, expansion of necrotic core and hence plaque vulnerability. Increased expression of VEGF and its receptors accompany neoangiogenic process. We used 99m Tc -labeled single chain VEGF (TcV) for developing potentially noninvasive imaging modality in experimentally induced aortic atherosclerotic lesion. Methods : Noninva-sive radionuclide imaging was performed with TcV (6.85 ±0. 27 mCi) in 6 NZW rabbits receiving high cholesterol diet (0.2% cholesterol, 4% fat) for one year and compared with 3 control rabbits receiving normal rabbit chow. Four hours after intravenous administration of TcV, micro SPECT/microCT imaging was performed for in vivo localization of tracer activity. Aortas were then explanted, and gamma counted for determination of % injected dose per gram (%ID/g). The aortas were then submitted for histopathologic characterization. Results : The uptake in thoracic aorta was clearly visualized non-invasively by TcV in vivo imaging in 4 of 5 rabbits in hypercholesterolemic rabbits, but not in the control animals. The %ID/g of each parts of aorta in hypercholesterolemic rabbits (Arch : 0.036 ± 0.020 %, Thoracic : 0.026 ± 0.012 %, Abd : 0.019 ± 0.009 %) was about 2.5-fold higher than that in control group (Arch : 0.014 ± 0.004 %, Thoracic : 0.009 ± 0.003 %, Abd : 0.009 ± 0.003 %) (figure a ). Ex vivo images of each group are shown as figure b . Conclusions : This preliminary study suggests a potentially novel strategy for non-invasive imaging of neoangiogenesis in atherosclerotic plaque and may allow identification of unstable plaques.