Computational imaging of aortic vasa vasorum and neovascularization in rabbits using contrast-enhanced intravascular ultrasound: Association with histological analysis

Özet

Objective: Neoangiogenesis is pathophysiologically related to atherosclerotic plaque growth and vulnerability. We examined the in vivo performanceof a computational method using contrast-enhanced intravascular ultrasound (CE-IVUS) to detect and quantify aortic wall neovascularizationin rabbits. We also compared these findings with histological data.Methods: Nine rabbits were fed with a hyperlipidemic diet. IVUS image sequences were continuously recorded before and after the injection ofa contrast agent. Mean enhancement of intensity of a region of interest (MEIR) was calculated using differential imaging algorithm. The percentdifference of MEIR before and after the injection of microbubbles (d_MEIR) was used as an index of the density of plaque or/and adventitialneovascularization. Aortic segments were excised for histological analysis.Results: CE-IVUS and histological analysis were performed in 11 arterial segments. MEIR was significantly increased (~20%) after microbubbleinjection (from 8.1±0.9 to 9.7±1.8, p=0.016). Segments with increased VV/neovessels in the tunica adventitia (histological scores 2 and 3) hadsignificantly higher d_MEIR compared with segments with low presence of VV/neovessels (score 1); 40.5±22.9 vs. 8±14.6, p=0.024, respectively.Conclusion: It is possible to detect VV or neovessels in vivo using computational analysis of CE-IVUS images, which is in agreement with histologicaldata. These findings may have critical implications on vulnerable plaque assessment and risk stratification.