Imaging Study Of Chinese Miniature Pig Cardiac Circulatory Disorders

The First Part:Integrated imaging study of acute myocardial ischemia in Chinese mini-swine modelObjective To study the Multi-Detector Row Computed Tomography(MDCT), Magnetic Resonance Imaging(MRI) and Single Photon Emission Computed Tomography(SPECT) detected acute myocardial ischemia in Chinese mini-swine model.Materials and Methods A total of six mini-pigs,body weight(21.6±1.2) kg,all male.MDCT scaned the pig first.Then distal segment of Left Anterior Descending Artery was ligated.In the 2h～8h after ligation,MDCT scan was given every 2h.MRI, SPECT and the last MDCT scan were given within 24 hours one after another.Finally pathological examination was given after pig got killed.Results One died of ventricular fibrillation,5 had the results.Pathological examination showed that myocardial infarction in 5 pigs generally range from apical,anterior and septal of left ventricular.Infarction model are transmural myocardial infarction most.Reduce perfusion regions of SPECT showed same location of infarct regions with pathology.Reduced first-pass perfusion regions in MRI showed same location of infarct regions with pathology.Delayed scanning of MRI did not show significantly delayed enhancement.Reduced first-pass perfusion regions in MDCT scan of 2h,4h,6h,8h and 24h all showed same location of infarct regions with pathology.Three pigs in the 4h～8h scan showed strengthened the edge of reduced perfusion regions in delayed scan.All 5 pigs showed no delayed enhancement at 24h scan.Mean value of the reduced first-pass perfusion region from preoperative to postoperative 2h～8h and 24h MDCT scan was followed bythe 75.91HU,36.43HU,35.21HU,37.8HU,37.39HU,33.32HU. Mean value of the normal first-pass perfusion region from preoperative to postoperative 2h～8h and 24h MDCT scan was followed by the values 84.16HU,89.78HU, 93.23HU,90.77HU,89.3HU,89.4HU.At p=0.05 level,repeated measures analysis of variance showed that over the time,first-pass perfusion CT values of reduced perfusion regions and normal perfusion regions are significantly different(F=8.221,p＜0.001).At p=0.05 level,one-way ANOVA analysis showed that the value of the reduced first-pass perfusion region is not exactly the same over time(F=33.649,p＜0.001),2h～8h and 24h had no difference between each other(p=0.792),the value of preoperative MDCT scan was different(p＜0.001).Preoperative and postoperative 2h～8h,24h average volume of SV(Stroke Volume) were 21.7ml, 11.9ml,10.3ml,11.4ml,12.3ml,12.6ml,respectively.Preoperative and postoperative 2h～8h,24h average volume of ESV(End-Systolic Volume) were 15.2ml,23.4ml,25.0ml,24.4ml,25.3ml,22.8ml,respectively.Preoperative and postoperative 2h～8h,24h average volume of EDV(End-Diastolic Volume) were 37ml,35.4ml,35.0ml,35.7ml,37.6ml,37.5mll,respectively.Peoperative and postoperative 2h～8h,24h average percentage of ejection fraction(Ejection FFraction EF) were 58.9%,33.8%,29.0%,31.9%,32.6%,33.5%.,respectively.EF(F =27.240,p＜0.001),EDV(F=2.339,p=0.079) had no statistically significant change.SV(F=22.349,p＜0.001) ESV(F=8.810,p＜0.001) were statistically significant different.The mean parameters of MRI were SV9.8ml,ESV21.5ml, EDV22.8ml,EF33.8%.At p=0.05 level,paired-samples t test showed that SV(t=-2.474,p=0.069),ESV(t=-0.258,p=0.809),EDV(t=-1.379,p= 0.240),EF(t=0.056,p=0.958),no statistical difference between MRI and MDCT. Myocardial infarction rates of pathology in 5 pigs were 37.10%,58.70%,31.30%, 26.80%,25.60%,respectively.Myocardial infarction rates of MDCT in 5pigs were 24.20%,63.30%,34.30%,47.00%,28.00%,respectively.Myocardial infarction rates of MRI in 5pigs were 38.20%,61.20%,32.60%,25.30%,21.50%, respectively.At p=0.05 level,paired-samples t test showed that no statistical difference between pathology and MDCT(t=0.612,p=0.574),no statistical difference between pathology and MRI(t=0.820,p=0.458),no statistical difference between MDCT and MRI(t=0.425,p=0.692).Conclusions MDCT,MRI and SPECT were all able to show the myocardial infarction in acute myocardial ischemia model well.MDCT,MRI and pathology showed the infarct size well related between each other. The Second Part:Integrated imaging study of chronic myocardial ischemia in Chinese mini-swine modelObjective To study the Multi-Detector Row Computed Tomography(MDCT), Magnetic Resonance Imaging(MRI) and Single Photon Emission Computed Tomography(SPECT) detected chronic myocardial ischemia in Chinese mini-swine model.Materials and Methods A total of six mini pigs,all male,body weight(22.7±1.4) kg.All pigs accepted MDCT scan first,then an Ameroid narrow ring was placed on Left Anterior Descending Artery within 1 week.MDCT,MRI and SPECT were given on the same day.The other SPECT was given on the 27^th day,then coronary angigraphy,MDCT,MRI were given on the 28^th day.Finally,killed animals and gave pathological examination.Results Two pigs died of heart failure during the process of rearing,4 had the results.Pathology showed 3 pigs had subendocardium infarction,1 had no infarction.Coronary Angiography showed anterior descending artery stenosis were higher than 50%in 3 pigs with infarction.MRI showed no reduced first-pass perfusion or delayed enhancement in 1 pig,reduced first-pass perfusion but no delayed enhancement in 2 pigs,reduced first-pass perfusion and delayed enhancement in 1 pig.SPECT in the 3 pigs showed reduced left ventricular anterior wall perfusion,1 pig had no reduced perfusion.MDCT showed stenosis of left anterior descending coronary arteryin is more than 50%in 3 pigs.Significant reduced first-pass perfusion regions could be seen in 3 pigs,but no delayed enhancement region was seen.Two pigs showed reduced first-pass perfusion regions but no delayed enhancement region.MDCT showed preoperative day,the 1^st postoperative day and the 28^th postoperative day of cardiac function.At p=0.05 level,SNK test were as follows:SV(Stroke Volume,) followed by the average volume of 20.5ml,22ml,15.2ml(F=3.330,p=0.106);ESV (End-Systolic Volume) followed by the average volume of 15ml,17.2ml,26.2ml (F=10.820,p=0.010);EDV(End-Diastolic Volume,) followed by the average volume of 38ml,39.2ml,41.4ml(F=1.132,p=0.383);EF(Ejection FFraction) followed by the average percentage of 54.4%,53.1%,36.7%(p=2.802,F=0.138). ESV increase was statistically significant,there was no statistical difference in other parameters.MRI showed the 1^st postoperative day and the 28^th postoperative day of cardiac function.At p=0.05 level,the sample-paired t test were as follows:SV followed by the average volume of 11.8ml,11.1ml(t=0.161,p=0.883);ESV the average volume of 13ml,27.3ml(t=-3.146,p=0.051);EDV were the average volume of 24.7ml,38.2ml(t=-19.817,p＜0.001);EF were the average percentage of 47.9%,30.2%(t=1.693,p=0.189).The increase in EDV was statistically significant,there was no statistical difference in other parameters.MDCT and MRI were compared by sample-paired t test at the level of p=0.05:SV(t=4.054,p= 0.005),ESV(t=0.665,p=0.527),EDV(t=2.680,p＜0.032),EF (t=1.791,p=0.116).MDCT of the SV,EDV were higher than MRI,but both ESV and EF was no statistical difference.At p=0.05 level,using the SNK test to analyze the changes of mean first-pass perfusion CT value on preoperative day,the 1^st postoperative day and the 28^th postoperative day.Mean ventricular anterior wall value were 75.6HU,80.66HU,46.73HU(F=10.274,p=0.011);mean septal mean CT were 78.53HU,82.85HU,82.12HU(F=1.020,p=0.339);mean left ventricular wall CT mean,respectively 73.34HU,76.92HU,67.08 HU(F=4.233, p=0.070).CT value of Left ventricular anterior wall were statistical difference.Conclusions MDCT,MRI and SPECT could show the region of chronic myocardial ischemia.They were all limited to show little subendocardium infarction. The Third Part:Integrated imaging study of myocardial microcirculation disturbance in Chinese mini-swine modelObjective To study the Multi-Detector Row Computed Tomography(MDCT), Magnetic Resonance Imaging(MRI) and Single Photon Emission Computed Tomography(SPECT) detected myocardial microcirculation disturbance in Chinese mini-swine model.Materials and Methods Eight Chinese mini pigs,all male,body weight(22.8±0.9) kg.All pigs got MDCT scan first,then 10⁵ microspheres (100μm) were injected in the middle piece of left anterior descending artery in 1 week.SPECT was given 27 days later.Coronary angigraphy,MDCT,MRI were given on the 28^th day.Finally,animals were killed and pathological examination was given. Results Three pigs died of ventricular fibrillation,one pig died due to heart failure in the rearing process,four pigs got all inspections.No pathological staining infarction was found.All models got microcirculation disturbance of little myocardial.Using sample-paired t test to analyse changes in MDCT cardiac function at p=0.05 level.SV (Stroke Volume) of MDCT preoperative and 28th day were the average amount of 17.5ml,17.9ml,no statistical difference between the two(t=-0.329,p=0.746).The average volume of ESV(End-Systolic Volume) of MDCT preoperative and 28th day were the average amount of 16.4ml,16.8ml,no statistical difference between the two (t=-0.577,p=0.604).EDV(End-Diastolic Volume) of MDCT preoperative and 28th day were the average amount of 33.9ml,34.9ml,no statistical difference between the two(t=-1.190,p=0.320).EF(Ejection Fraction) of MDCT preoperative and 28th day were the average amount of 51.8%,54.2%,no statistical difference between the two(t=-1.736,p=0.181).The average amount of SV of MRI on the 28^th day was 14.8ml,The average amount of ESV of MRI on the 28^th day was 15.5ml,The average amount of EDV of MRI on the 28^th day was 30.6ml,The average amount of EF of MRI on the 28^th day was 48.6%.At p=0.05,comparing MDCT and MRI parameters of cardiac function by sample-paired t test.SV(t=1.058,p=0.368),ESV(t=0.548, p=0.622),EDV(t=1.928,p=0.149),EF(t=1.513,p=0.227),there were no statistical difference.At p=0.05 to analyse the CT value changes of MDCTin the use of sample-paired t test.MDCT scan of left ventricular anterior wall first-pass perfusion CT values of the average before and after operation were 73.34HU,69.06HU (t=0.937,p=0.418),delayed 1min note the value of the average preoperative and postoperative CT were 66.08HU,52.37HU(t=1.425,p=0.249),3min note the average value of preoperative and postoperative CT were 73.34HU,69.06HU(t= 0.937,p=0.418),5min note the average value of preoperative and postoperative CT were 60.07HU,48.52HU(t=1.290,p=0.288),10min note the average preoperative and postoperative CT values were 54.00HU,55.96HU(t=2.313,p= 0.314),no statistical difference were found.Ventricular septal average first-pass perfusion CT values of preoperative and postoperative 71.64HU,72.85HU(t=1.546, p=0.220),delayed injection 1min average preoperative and postoperative CT values were 61.94HU,67.1HU(t=2.421,p=0.094),3min note the average value of preoperative and postoperative CT were 68.52HU,53.17HU(t=0.069,p=0.950), 5min note the average value of preoperative and postoperative CT were 60.37HU, 49.55HU(t=2.292,p=0.106),10min note the average preoperative and postoperative CT values were 46.84HU,46.26HU(t=0.125,p=0.909),no statistical difference were found.Left ventricular wall first-pass perfusion CT values of the average before and after operation were 76.75HU,79.51HU(t=-0.812,p= 0.735),delayed lmin Note the value of the average preoperative and postoperative CT were 71.36HU,77.56HU(t=2.421,p=0.476),3min note the average value of preoperative and postoperative CT were 65.50HU,60.78HU(t=0.569,p=0.609), 5min note the average value of preoperative and postoperative CT were 54.41HU,54.35 HU(t=0.013,p=0.991),10min note the average preoperative and postoperative CT values were 54.50HU,56.52HU(t=-0.327,p=0.765),no statistical difference were found.MDCT showed no reduce the first-pass perfusion region in Left ventricular anterior wall,interventricular septum,left ventricular wall,no delayed enhancement was found either.MRI showed no reduce the first-pass perfusion region in Left ventricular anterior wall,interventricular septum,left ventricular wall,no delayed enhancement was found either.SPECT are not reduce regional perfusion.SPECT showed no reduced perfusion region in Left ventricular anterior wall,interventricular septum, left ventricular wall.Conclusions MDCT,MRI,SPECT detected microcirculation disturbance of little myocardial on Chinese mini-pigs are limited.