Ultrasmall Superparamagnetic Iron Oxides Enhancement Magnetic Resonance Imaging To Detect Atheromatous Plaques Of Abdominal Aorta In Rabbits And Ezetimibe Effect On Vascular Inflammation After Vascular Injury

Section1: Ultrasmall Superparamagnetic Iron Oxides enhancementMagnetic Resonance Imaging to detect atheromatousplaques of abdominal aorta in rabbits.Objective: To establish atherosclerotic experiment in rabbits by high fatdiet Plus balloon injury and explore the feasibility of Ultrasmall Superpara-magnetic Iron Oxides enhancement Magnetic Resonance Imaging to detectatheromatous plaques of abdominal aorta in rabbits.Methods:40New Zealand white rabbits after one week normal diet weredivided into2groups randomly as the experiment group (n=20) and thecontrol group (n=20). MR Imaging was performed on a3T MR when thecontrol group were fed with normal diet for12weeks. Then0.9%physiolo-gical saline was infused intravenously, MR Imaging was performed on a3TMR system immediately and5days later again. The experiment group werefed with high fat diet after balloon injury for12weeks, then MR Imaging wasperformed on a3T MR. After that, Ultrasmall Superparamagnetic Iron Oxideswas infused intravenously, then MR Imaging was performed on a3T MRsystem immediately、1days、3days and5days. At the same time,Measurements of the intraluminal signal to noise ratio、the vessel wall signalto noise ratio and the reduction in transversal area was performed on theprecontrast image set. After the last scan, all rabbits were executed to getaortic specimens，and stained with following：（1）hematoxylin and eosin（HE）stain；（2）Prussian blue stain. On the control group blood serum totalcholesterol(TC) and low density lipoprotein (LDL)were measured on1week and12weeks after normal diet; on the experiment group blood serum totalcholesterol(TC) and low density lipoprotein (LDL)were measured on1weekafter normal diet and12weeks after balloon injury.Results:1Both TC and LDL were significantly inereased in experiment groupcompared with the control group.2There were crescent-shaped plaques in the lumens of MagneticResonance Imaging of the experiment group.3In the USPIO enhanced MRI scanning images, we can see the sizes ofthe filling defect respectively in the T2WI and T2*sequence and the mostobvious change appearance on the5days.4The intraluminal SNR values fell to the lowest when USPIO wasinjected instantly and increased with the extension of time, at the same timethe vessel wall signal to noise ratio(SNR) values decreased gradually and thereduction in transversal area increased gradually.Conclusions:1High fat diet and balloon injury can establish a good rabbit experimentof atherosclerosis.2MRI can developing plaques, and the results of MRI consistent withthe pathological results.3The macrophages engulfed USPIO particles in the AS plaques canmake filling defect in the T2WI and T2*sequence, and extend clearly as theextension of time and the most obvious change appearance on the5days.4USPIO enhancement MRI showed filling defect parts consistent withpathological results showed macrophages location.Section2: Ultrasmall Superparamagnetic Iron Oxides enhancementmagnetic Resonance Imaging to detect Ezetimibe effectionon vascular inflammation after vascular injury Objective: Compared with the changing of the SNR value, the reductionin transversal area, the intima-media thick-ness(IMT) and the percentage ofthe macrophages between the intervention group and the experiment group toevaluate the effect of Ezetimibe on vascular inflammation after vascularinjury.Methods:40New Zealand white rabbits after one week normal diet weredivided into2groups randomly as the experiment group (n=20) and theintervention group (n=20). The experiment group were fed with high fat dietfor12weeks after balloon injury and the intervention group give theEzetimibe5mg/kg/day on the basis of high-fat feeding. Blood serum totalcholesterol(TC) and low density lipoprotein (LDL)were measured at1weeknormal diet and12weeks after balloon injury both in the experiment groupand the intervention group. Then MR Imaging was performed on a3T MR.After that, Ultrasmall Superparamagnetic Iron Oxides was infusedintravenously, then MR Imaging was performed on a3T MR systemimmediately and on1days、3days and5days. At the same time theintraluminal signal to noise ratio(SNR)、the vessel wall signal to noiseratio(SNR) and the reduction in transversal area was performed on theprecontrast image set. At last, all rabbits were executed to get aorticspecimens，and stained with hematoxylin and eosin （HE）and Prussian blue,then measured the intima-media thick-ness(IMT) and the percentage of themacrophages.Results:1Both TC and LDL were significantly decreased in intervention groupcompared with the experiment group.2USPIO enhancement MRI scan and MRI scans were visible lessplaque numbers and deposition of lipid in the intervention group than theexperiment group.3As the extension of time, the vessel wall signal to noise ratio(SNR)values decreased gradually and the reduction in transversal area increased gradually both in the experiment group and the intervention group. The SNRvalues and the reduction in transversal area were no statistically significantdifference between the two groups on the fifth day.4The pathologic result were visible less plaque numbers and depositionof lipid in the intervention group than in the experiment group. There was nostatistically significant difference between the percentage of the macrophageand the intima-media thick-ness(IMT) within the intervention group andexperiment group.Conclusions:1Ezetimibe can decrease the serum TC and LDL levels and reducedeposition of lipid in the plaques as a selective cholesterol absorptioninhibitor.2Our research did not find that Ezetimibe can reduce plaquemacrophages in invasion.