超声、高分辨率磁共振成像技术在诊断评估兔颈动脉粥样硬化中的应用研究

Application of ultrasound and high-resolution magnetic resonance imaging in the diagnosis and evaluation of carotid atherosclerosis in rabbits

目的利用超声、高分辨率磁共振成像(HRMRI)技术,分析评价兔颈动脉粥样硬化(AS)模型的病变程度,为颈动脉AS动物模型的诊断评估提供技术方法。方法取雄性日本大耳白兔18只,随机分为正常对照(NC)组和模型(Model)组,每组9只,模型组饲喂高胆固醇饲料2周后行右侧颈动脉球囊损伤术,术后继续高脂饲喂6周,建立兔颈动脉AS模型,NC组饲喂常规饲料至8周。造模4周、8周时检测血浆总胆固醇(TC)和甘油三酯(TG)并超声检查颈动脉,造模8周时行颈动脉高分辨率磁共振成像(HRMRI)检查,行安死术后取右侧颈总动脉行HE染色和油红"O"染色,评估颈动脉AS病变。结果与NC组比,模型组兔造模4周时血浆TC显著升高(P<0.05),8周时体重、血浆TC、TG均显著增加(P<0.05,P<0.01);超声结果显示,模型组兔的右侧颈总动脉内中膜厚度(IMT)、狭窄率、收缩期最高血流速度、血管阻力指数均随病变程度加深而显著增加(P<0.05,P<0.01),并可见狭窄和斑块形成;HRMRI结果亦显示,MIP成像可见右侧颈总动脉明显狭窄,3D-TOF成像可见模型组兔有明显的AS斑块且狭窄率显著增加(P<0.01);组织病理学证实模型组兔颈总动脉有明显的AS斑块形成,IMT、狭窄率、脂质含量均比NC组显著增加(P<0.01);相关性分析结果表明超声、HRMRI与HE染色的定量分析结果显著相关(P<0.01)。结论超声和HRMRI技术均能无创检测诊断兔颈动脉粥样硬化模型的病变,但HRMRI更能清晰、直观地判断血管狭窄及AS斑块严重程度。

Objective The aim of this study was to evaluate the application of ultrasound and high-resolution magnetic resonance imaging(HRMRI)in a rabbit carotid atherosclerosis(AS)model,providing technical method for the diagnosis and evaluation of preclinical atherosclerotic plaques.Methods Eighteen male Japanese white rabbits were randomly divided into two groups(n=9).The model group was fed a high-cholesterol diet for 2 weeks followed by balloon injury to the right carotid artery.After surgery,high-fat feeding was continued for 6 weeks to establish a rabbit carotid AS model.The NC group was fed regular feed for 8 weeks.At 4 and 8 weeks after modeling,plasma total cholesterol(TC)and triglyceride(TG)levels were measured,and the carotid artery was examined via ultrasound.Carotid HRMRI was performed at 8 weeks.After euthanasia,the right common carotid artery was taken for HE and oil red"O"staining to assess carotid artery atherosclerotic lesions.Results Compared with the findings in the NC group,TC levels were significantly higher in the model group at 4 weeks after modeling,and body weight and TC and TG levels were significantly higher in the model group at 8 weeks.The result of ultrasound revealed that intima-media thickness(IMT),the stenosis rate,the maximum systolic blood flow velocity,and the vascular resistance index of the right common carotid artery increased significantly in the model group with the deepening of the lesions,and stenosis and plaque formation were observed.In addition,the HIMRI result disclosed obvious stenosis of the right common carotid artery compared with findings in the NC group,and the model group displayed obvious atherosclerotic plaque formation and a significantly higher stenosis rate.Histopathology further confirmed the obvious atherosclerotic plaque formation in the common carotid artery in the model group,and IMT,the stenosis rate,and lipid content were significantly higher in the model group than in the NC group.In addition,correlation analysis demonstrated that the quantitative result of ultrasound,HRMRI,and HE staining were significantly correlated.Conclusions Both ultrasound and HRMRI technology can non-invasively detect and diagnose lesions in a rabbit carotid AS model,but HRMRI can more clearly and intuitively judge the severity of vascular stenosis and atherosclerotic plaques.