| Part one MRI, mPET/CT evaluation value of SD rat model of MCAOObjective:According to the modified Zea-Longa suture method for preparing SD rat right middle cerebral artery occlusion (MCAO) model of cerebral ischemia. Using imaging (MRI, mPET/CT) to evaluate SD rat MCAO model, analyze rat brain SD 0.5h-12hADC value changes of ischemia, discuss DWI and mPET/CT sensitivity to cerebral ischemia. Materials and methods:There need 49 healthy SD rats. Pre-experiment 3 rats, in formal experiment 46 rats were randomly divided into ischemic group 36 rats,10 rats in the control group.Pre-experiment and formal experiment ischemia group according to the modified Zea-Longa suture method [1] making SD rats MCAO model in the right neck, suture tissue in control group after exposure of the right common carotid artery. Ischemia group divided into group MRI and group mPET/CT imaging. Group MRI suture placed after the success of 0.5h,1H,2h,4h,6h,8h, 12h underwent MRI scanning (scanning sequence is DWI, T2WI, FLAIR, T1 WI), ADC value determination of focal ischemia. The mPET/CT group, the control group after 0.5h F-FDG head mPET/CT imaging,12h after operation were examined by MRI. Determine mPET/CT group, the left hemisphere ischemic control group and right hemisphere SUV mean value. Statistical data using SPSS13.0 software.Statistics 0.5h-12h values of ADC of SD rat DWI positive sequence 0.5h after operation in MRI group, drawing ADC value time curve, and hypothesis testing, based on P<0.05 equation was established. Statistical mPET/CT group, cerebral ischemia, the left hemisphere of the brain region of interest SUV mean, t test analysis; rats right hemisphere SUV mean mPET/CT group and the control value, t test, P< 0.05 was statistically significant. The experimental groups of SD rats after 0.5h of MRI group and mPET/CT group were four qualitative data tables Fisher exact probability method χ2 test, P<0.05 had statistical significance. Pre-experimental group, ischemia group made the suture placed 2.2±0.3cm die success criteria, and the SD rat survival over 6h and postoperative 12hMRI check DWI, T2WI, FLAIR series on the right hemisphere brain artery supply area showed high signal.5 level classification of all the rats was carried out according to Longa[1] neurological function score. Group MRI, check the 12hMRI mPET/CT group, the control group after each choose 10 rats,5 rats in each group. TTC staining, HE staining in 5. The pathological picture consists of vice director of Department of pathology physician diagnosis. Results:The pre-experimental group’s success in l,and the successful rate was 33.3%. The experimental group of 5 rats in intraoperative or postoperative died within 0.5h, successful model 31, the success rate is 86.1%. MRI group are with 21 SD rats. DWI series:after 0.5h 18 SD rats right cerebral hemisphere increased signal, after 1h 20 SD rats right cerebral hemisphere increased signal, after 2h,4h,6h,8h,12h were seen 21 SD rats, the right side of the brain signal with high signal. FLAIR, T2WI series:after 4H 12 SD rats right cerebral hemisphere increased signal, after 6h 15 SD rats, the right side of the brain signals increased, increased 8h visible after 19 SD rats right cerebral hemisphere signal, and after the increase of 12h from 21 SD rats, the right side of the brain signals. T1WI series:1 SD rats after 12h in the right hemisphere slightly low signal. MRI group of 0.5hDWI sequences of positive 0.5h,18 SD rats, the right brain is high signal area of 1h, 2h,4h,6h,8h,12h and ADC value (mm2/106s) were 480.15±21.46,450.81± 17.44,418.17±8.33,385.67 ±19.55,357.15±9.74,332.30±5.34,308.07 ±22.59. To draw the ADC value time regression curve equation was y=-14.372x+459.113, r=0.912, P<0.05. Regression equation was established, ischemia for 12 hours with ADC value decreased. MPET/CT group of 10 male SD rats 18F-FDG head mPET/CT imaging, the right side of the brain uptake reduce or imaging agent uptake defect area, and SUV mean was 2.31±0.35, the left hemisphere SUVmean3.63±0.40, visible on the right side of the brain after 12hMRI corresponding to high signal (DWI, FLAIR, T2WI). The control group after 0.5h mPET/CT bilateral hemisphere scintigraphy showed no abnormal uptake, right hemisphere SUVmean was 3.71±0.38, postoperative 12hMRI scan signal. The mPET/CT groups of SD rats ischemia 0.5h of bilateral cerebral hemisphere SUV mean values of t test, t=7.74, P<0.05 had statistical significance. The mPET/CT group and 0.5h the right side of the brain SUV mean value control group SD rats after t test analysis, t=9.32, P<0.05, there was statistical significance. MRI group and mPET/CT group after 0.5h qualitative data with the four Fisher exact probability method x2 test, P> 0.05, no statistical significance. The experimental groups of SD rats with 12hMRI TTC staining in ischemic region,0.5hmPET/CT check ischemic areas. HE staining showed that ischemic zone pale staining, a sieve mesh, nerve cell degeneration, necrosis, glial fibrillary disintegration, liquefaction, in some areas a focal necrosis, ischemia margin zone scattered in the red blood cells and inflammatory cells infiltration. The control group by TTC staining, HE staining revealed no abnormalities. Conclusion:1. The suture method can establish stable and reliable MCAO SD rat model.2. MRI examination can be used in MCAO rat model of evaluation and follow-up observation, can be found after 0.5h-2hDWI ischemia.0.5h-12hADC value is lower, FLAIR, T2WI sequence in 4-12h after ischemia appeared high signal.3. PET/CT in the diagnosis of cerebral ischemia in SD rats with high sensitivity, ischemia 0.5h can find focal ischemia reduced SUV.Part two MRI studies on brain of dead SD ratsObjective:After the establishment of MCAO model, scanning the SD rat’s brain tissue by the MRI,To observe the image of infarction after death,To explore the causes of death of cerebral infarction by imaging examination for diagnosis of feasibility. Method:The experimental group was the right brain is the establishment of improved Zea-Longa suture method of artery occlusion (MCAO) model score was 3-4 points,13h-56h death after embolization in 12 SD rats. The control group uses excess anesthetic intraperitoneal injection which caused 5 SD rats dead.Experiment group 12 SD rats arterial cerebral is chemia in vivo 12h MRI scanning, the control group after anesthesia in excess 0.5h MRI scanning.Put the two groups of SD rats in the room with temperature 10-15℃ and relative humidity 45%-55%t, after the death of 8h,24h,48h,72h, 96h repeated head MRI scan.The experimental group SD of rat cerebral infarct, determination of contralateral brain tissue ADC and the control group of right hemisphere ADC value.After The experimental groups of SD rats dead,8h,24h 48h,72h each take a mouse’s brain tissue HE staining,8 after the dead 96h brain tissue removed HE pathological staining. A control group of 5 SD rats 96h brain tissue was taken out to do HE staining,all pathological picture by pathology physician diagnosis.Statistical data using SPSS 13.0 software.The experimental group and the control group of SD rats died right hemisphere ADC repeated analysis of variance;The experimental groups of SD rats of right hemisphere infarction and non-infarction of left hemisphere after the death of ADC value of repeated analysis of variance, all with P<0.05 had statistical significance.The experimental groups of SD rats after the death of 8h,24h,48h, 72h,96hcerebral infarction ADC values and in vivo cerebral infarction ADC value of two two paired t test.The experimental groups of SD rats after the death of 8h,24h,48h,72h,96hleft hemisphere ADC values and ADC values in the left hemisphere of two two paired t test.Groups of SD rats after the death of 8h,24h,48h,72h,96h right hemisphere ADC values and ADC values in the right cerebral hemisphere of two two paired t test control, all with P<0.05 had statistical significance.Result:After the SD rat which in the experimental group cerebral infarction 12h and scanning after the SD rat dead 8h、24h、48h、72h、 96h,from each point we can see the high signal of the right of right cerebral hemisphere of the SD rat(DWI、FLAIR、T2WI).The left hemisphere near the midline area of different level signal,After the SD rat dead 48h、72h、96h the edge of the high signal area became fuzzy.PMMRI showed the eight SD rats’ brain midline structure left shift.The scanning of Control group MRI has no abnormal high signal.The experimental group SD lesions in rats with cerebral infarction (ischemic 12h) in vivo,after death 8h,24h,48h,72h,96h the ADC value were 304.50±19.07,260.83±16.52,209.27±22.73,179.70±27.96, 153.89±20.23,135.86±24.19,The experimental groups of SD rats in vivo left in non infarct zone (12h after operation),after dead 8h,24h,48h,72h,96h the ADC value were 607.50±75.29,352.41±9.50,282.73±32.21,238.60± 24.01,197.22±6.32,174.50±21.28.The control group right cerebral hemisphere in vivo, after the death of 8h,24h,48h,72h,96h ADC (mm2/106s) were 626±66.49,358.80±2.30,285.20±1.04,246.80±6.89,192.80± 11.32,179.20±18.31.The ADC repeated analysis of variance of SD rats’ right hemisphere of the experimental group and the control group.F=39.54, P<0.05, Statistical significance;The experimental groups of SD rats of right hemisphere infarction and left hemispheric non repeated analysis of variance, ADC value of infarction after the death of F=42.91, P<0.05.The experimental groups of SD rats after the death of 8h,24h,48h,72h,96hinfarct ADC values were associated with in vivo infarct ADC value of two two paired t test,The T values were 8.13, 13.31,14.36,20.31,19.79, P<0.05,The experimental groups of SD rats after the death of 8h,24h,48h,72h,96hleft hemisphere ADC values and ADC values in the left hemisphere of two two paired t test, the T values were 10.25,12.44, 13.98,16.71,18.84, P<0.05;group SD rats after the death of 8h,24h,48h,72h, 96h the right brain hemisphere of brain tissue ADC values were associated with right hemisphere brain tissue in vivo with ADC values of two two paired t test control, t values were 7.32,10.64,16.21,14.66,16.62, P<0.05, there was statistical significance.Conclusions:1. SD rat cerebral infarction died within 13h-56h, stored at room temperature 10-15 ℃, relative humidity of 45% to 55% of the environment, died within 96h MRI imaging DWI, FLAIR, T2WI sequence infarct showed high signal.postmortem infarction brain tissue ADC value is lower than non-infarcted brain tissue ADC value.MRI can be used for cerebral infarction virtual autopsy of death.2. SD rat cerebral infarction died 8h-96h non-infarcted brain tissue ADC value is lower than non-infarcted brain tissue in vivo ADC values. SD rat cerebral infarction 8h-96h postmortem brain tissue infarction ADC values is below infarcted brain tissue in vivo ADC values. SD rats anesthetized accidental death 8h-96h ADC values is below the brain tissue in vivo brain ADC values. |
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