超声造影动态评价不同阶段的兔腹主动脉斑块内新生血管密度的研究

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

目的应用超声造影技术动态观察不同阶段的兔腹主动脉斑块内新生血管的密度,探讨不同阶段斑块新生血管密度的差异及其影响因素。方法 30只日本大耳朵白兔,以扩张球囊损伤腹主动脉后,再分别高脂饲养8周(10只,A组)、12周(10只,B组)、16周(10只,C组),建立动脉粥样硬化模型;高脂饲养结束时行常规超声及超声造影检查,观察动脉内中膜复合体厚度、斑块厚度和斑块增强强度以及斑块增强强度与管腔增强强度的比值。造影结束后处死实验兔,取斑块组织,并以CD31染色观察斑块内新生血管的密度。比较3组间上述各参数的差异。结果 C组实验兔腹主动脉内中膜复合体厚度、斑块厚度、斑块内新生血管密度、血脂水平、斑块增强强度以及斑块增强强度与管腔增强强度的比值均大于A组和B组,B组实验兔上述参数均大于A组(均P<0.001)。斑块增强强度以及斑块增强强度与管腔增强强度的比值均与斑块内新生血管的密度具有良好的相关性(r=0.795,P<0.001;r=0.704,P<0.001)。结论超声造影技术可以定量评价斑块新生血管的密度。斑块形成后期新生血管的密度高于斑块形成早期。斑块内新生血管的密度可能与血脂水平以及动脉内中膜复合体和斑块的厚度有关。

Objective To evaluate the neovascularization in plaques of different stages in a rabbit model of atherosclero- sis during contrast-enhanced uhrasonography （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 athero- sclerotic 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 neovaseularization density than early-stage plaques （P 〈 0. 001 for all）. There is a good correlation between the enhanced intensity of atherosclerotie 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. Neovaseularization density increased as athero- sclerosis progressed on both the CEUS measurements and histological evidence, which may be associated with the maxi- mum thickness of the plaques and serum lipids level.