Dynamic evaluation of neovascularization in plaques of different stages in a rabbit model of atherosclerosis during contrast-enhanced ultrasonography

Objective To evaluate the neovascularization in plaques of different stages in a rabbit model of atherosclerosis during contrast-enhanced ultrasonography (CEUS). Methods Abdominal aortic atherosclerosis was induced in 30 rabbits, and animals underwent standard ultrasonography and CEUS imaging of abdominal aorta at the end of the atherosclerotic induction period. The animals were euthanized after CEUS, and plaque specimens were harvested for histological staining of CD31. Results The late-stage plaques exhibited a higher serum lipids level, an increased intimal-medial thickness, an increased thickness of the plaques, a higher enhanced intensity, a higher ratio of enhanced intensity in the plaque to the lumen of the abdominal aorta, and an increased histological neovascularization density than early-stage plaques (P<0.001 for all). There is a good correlation between the enhanced intensity of atherosclerotic plaques and the histological neovascularization density (r=0.795, P<0.001). A significant correlation was also found between the ratio of enhanced intensity in the plaque to the lumen of the abdominal aorta (r=0.704, P<0.001). Conclusion CEUS imaging can be used to access intraplaque neovessels in real-time in vivo. Neovascularization density increased as atherosclerosis progressed on both the CEUS measurements and histological evidence, which may be associated with the maximum thickness of the plaques and serum lipids level.