Relationship between Enhanced Intensity of Contrast Enhanced Ultrasound and Microvessel Density of Aortic Atherosclerostic Plaque in Rabbit Model

The aim of this study was to evaluate the relationship between enhanced intensity of contrast enhanced ultrasound and microvessel density of aortic atherosclerotic plaque in rabbit model. The abdominal aortas of thirty-six male New Zealand rabbits were damaged by balloon expansion and the animals were then fed a high fat diet for 12 weeks. Twenty-seven plaques on the near aortic wall were detected using conventional ultrasound examination. The maximum thickness of each plaque was recorded. CEUS was performed on these 27 plaques and the time-intensity curves (TICs) were analyzed offline. Using the quantitative ACQ software, features such as the arrival time (AT), time to peak (TTP), baseline intensity (BI), peak intensity (PI) and enhanced intensity (EI) (EI = PI-BI) were assessed. Inter- and intra-observer agreement of EI were assessed using the Bland-Altman test. After CEUS examination, the rabbits were sacrificed for pathological examination and CD34 monoclonal antibody immunohistochemical detection. Microvessel density (MVD) was counted under the microscope. The relationship between indexes of CEUS and the level of MVD was analyzed. There was a good positive linear correlation between EI and MVD (γ = 0. 854, P<0. 001), the intraclass correlations for inter- and intra-observer agreement for EI were 0.73 and 0.82 respectively, suggesting that EI may be act as a useful index for plaque risk stratification in animal models.