| Objective: To explore the feasibility of establishing viable and infarcted myocardium model of rabbit by hanging and ligating the left anterior desending(LAD).Then referring the pathologic manifestation and determined if the model was successfully setup.We evaluated the correlation between the viability of myocardium and CT perfusion imaging,and to probe if dynamic scan of MSCT can determine the viability of ischemic myocardium.Materials:1.1 Experimental animal: 45 heath New Zealand rabbits(weight 2.5±0.3kg) were randomly divided into experimental group(n=40) and control group(n=5). The experimental group were subdivided into ligated group(n=20) and hung group(n=20).1.2 Model building1.2.1 Ligated GroupAfter basic anaesthesia,2%phenobarbitone were injected intravenously.Animal were lain on the back. The major pectoral muscle and minor pectoral muscle were dissected and the 4th to 6th rib were cut off.Then pericardium was cut carefully. When left auricular appendage was revealed,we can find left coronary artery by inferior margin of it.we ligated the ramus descendens of anterior arteriae coronariae sinistrae.The chest wall were closed after operating field were cleaned by physiological saline(PS).1.2.2 Hung Group:The operation is identical as the former mentioned method,but LAD was hanged for 15minute instead of tied.1.2.3 Control GroupThe method of operation is identical as the former mentioned method but nothing was done to LAD.1.3 The standard of success for experimental group.To determine if the operation was successful by observeing macroscopilly and microscopilly,including TTC stain,H&E stain,and immunochemiohistological examination.1.4 CT perfusion scanGE LightSpeed 16 MSCT was used with cine manner.The scaning span was from cardiac base to the apex.The parameters were: qualification(120kV,100mA),rotation time (0.4s/circuit), collimation(2.5mm), data collection mode (2.5mm×8).After pilot scan and plain scan was performed, iohexol or Iobitridol was injected intravenously (4ml ,0.3ml/s)while perfusion scan was made.1200 original images were acquisited. Delayed scan was performed 10 minute later with collimation of 2.5mm.Ad 4.2 perfusion software was used for postprocessing to get time-density curve. Metoprolol was injected intravenously before CT scan was performed to control heart rates to 60~80/min.1.5 PathologyAnimal were executed after overdose anaesthesia.Heart were taken out of chest,cut into 2.5mm slices according to scan plane.Part of sample was stained by 2%TTC bathe in 37℃water box.Others were fixed with 10%paraformaldehyde and stained by HE and immunohistochemistry.1.6 Analysis of statisticsSPSS13.0 statistics software was used to analysis the peak value,peak time and delayed scan CT value.α=0.05 was taken as the significant standard.Results:The ligated group's peak time(65±3.1sec) were longer than the hanging group's (51±1.8 sec),with statistics difference(t=9.068,p=0.038)The tied group's peak valu(e157.6±23.6Hu)were lower than that of the hanging group (210.9±16.8Hu),with statistics difference(t=9.068,p=0.038). The tied group's delayed scan value(89±15.3Hu) were higher than the hanging group's (58±13.9Hu),with statistics difference(t=10.07,p=0.0037).Conclusion:1.Postischemia viable myocardium model can be established by hanging or ligated LAD .The model is suitable to MSCT scan.2.MSCT perfusion scan can differentiate necrosis myocardium from viable myocardium by cine scan and delayed enhencement.
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