Evaluation Of Abdominal Aortic Vessel Wall Permeability And Texture Analysis Based On DCE-MRI In Early-Stage Atherosclerotic Rabbits-a Preliminary Study

PartⅠ: Quantitative Parameters of Dynamic Enhanced Magnetic Resonance Imaging to Evaluate Early Abdominal Aortic Atherosclerosis in RabbitsObjective To explore the feasibility of "black blood" dynamic enhanced magnetic resonance imaging（DCE-MRI）in the assessment of abdominal aortic vessel wall microvascular permeability and blood flow perfusion in early atherosclerotic rabbits.Methods Twenty healthy male New Zealand white-eared white rabbits aged 3months were fed with a high-fat diet combined with balloon-injured abdominal aorta to establish an atherosclerosis model（experimental group n=18,control group n=2）.3D-TOF,conventional T₂WI,T₁WI,and "black blood" DCE-MRI imaging examinations were performed on animal models at weeks 0,4,12,and 20 using clinical 3.0T MR equipment.GE Omni-Kinetics software Patlak model was used to measure the vessel wall volume transfer constant（K^trans）and plasma volume（Vp）.After 20 weeks,all animals were euthanasia,and the abdominal aorta was fixed and isolated.CD31 immunohistochemical staining was performed and neovascularization density（MVD）calculated.Repeated measurement analysis of variance was used to compare the permeability parameters at different times in two groups.The correlation between K^trans 、Vp and MVD were modeled by Pearson correlation analysis.Result The K^trans and Vp were not statistically different at different time points in control group.Compared with baseline,the K^trans and Vp values in experimental group increased significantly at week 20（both P<0.05）.The Pearson correlation analysis showed that the K^trans of vessel well in experimental group was moderately correlated with MVD（r=0.58,P<0.01）,and Vp was moderately correlated with MVD（r=0.43,P<0.01）.The abdominal aorta vessel wall was unevenly thickened,smooth muscle cells irregularly arranged,and the neovascularization significantly increased in experimental group at week 20.Conclusions It is feasible to evaluate the microvascular permeability of the rabbit abdominal aortic vessel wall in early atherosclerosis using the "black blood" DCE-MRI,which provides imaging monitoring means for early atherosclerotic lesions.Part Ⅱ Evaluation of Abdominal Aorta Vessel Wall Based on DCE-MRI Texture Analysis in Early-stage Atherosclerotic RabbitsObjective To investigate the feasibility of evaluating early lesions of the abdominal aorta vessel wall in atherosclerotic rabbits based on DCE-MRI texture analysis.Methods Twenty 3-month-old male New Zealand white-eared rabbits were fed with a high-fat diet and balloon injured abdominal aorta to establish an AS model（experimental group n=18 and control group n=2）.All animals were prepared for3D-TOF,conventional T₂WI,T₁WI,and “black blood” DCE-MRI imaging examinations at weeks 0,4,12,and 20.GE Omni-Kinetics software was used to analyze texture features on DCE-MR original image.And the texture feature parameters（mean,variance,skewness,kurtosis,correlation,entropy,IDM and contrast）were extracted.All animals were euthanasia after the scan completed,and the abdominal aorta was fixed and isolated.Sirius Red staining and Victoria Blue staining were performed.Repeated measures analysis of variance was used to compare the texture parameters at different time points in two groups.The receiver operating characteristic curve（ROC）was constructed and the area under the curve（AUC）was obtained to describe the diagnosis efficacy of the differential textural parameters in experimental group at week12 and baseline,and between week 20 and week 12.Results There was no significant differences of the texture parameters in the control group at different time periods.The mean,variance,skewness,kurtosis,correlation and entropy increased in experimental group.The mean,variance,and correlation were significantly different from baseline in experimental group at week12（all P<0.05）.The mean,variance,kurtosis,skewness,entropy,correlation,and contrast were statistically significant different from baseline in experimental group at week 20（all P<0.05）.The variance,skewness,entropy,correlation,IDM,and contrast were significantly different between week 12 and week 20（P<0.05）.AUC values of mean,variance,and correlation between 12 weeks and baseline were 0.734,0.938,and 0.719.The AUC values of variance,skewness,entropy,correlation,and IDM between 20 and 12 weeks were 0.813,0.863,0.998,0.913,and 0.938.The abdominal aorta vessel wall had a disordered arrangement of collagen fibers,increased collagen deposition area,and tightly arranged elastic fibers without obvious breakage in experimental group at week 20.Conclusion DCE-MRI texture analysis is feasible to evaluate early abdominal aortic atherosclerotic lesions in rabbits.