The Application Of CT Perfusion Combined Spectral Imaging In Evaluating The Ischemia Reperfusion Injury In Lower Limb Skeletal Muscle Of Rabbit

PART I Skeletal muscle CT perfusion combined spectral imaging:A feasibility study in rabbitsObjective:To investigate the feasibility of CT perfusion combined spectral imaging for evaluating the hemodynamics of the lower limb skeletal muscle in rabbit model.Methods:Eight New Zealand rabbits were fixed in a prone postion after anesthesia with Sumianxin? and sedation with pentobarbital sodium.Head perfusion pattern w as performed on GE revolution CT with a coverage of 16cm,including the both lo wer extremities.Quantitative perfusion parameters,blood flow(BF),blood volume(BV),mean transit time(MTT),time to peak(TTP)and spectral parameters,energy iodine value(EI)were measured by two radiologists separately at imaging postproc essing workstation.The quantitative perfusion and spectral parameters were compare d between thigh and shank using paired-t test and measurement reproducibility wa s evaluated using Bland-Airman analyse.Results:Lower limb artery anatomy of rabbits was similar to that of human.CT p erfusion color maps showed thigh and shank as homogeneous hypervascularity.Thig h had the slightly higher BF,BV,MTT values,the slightly lower TTP value and si milar El compared with shank[(5.56 ± 0.06)VS(5.49 ± 0.13)ml/100g/min,(1.76+0.05)VS(1.73 ± 0.1)ml/100gg(19.33+0.86)VS(19.00 ± 1.12)S,(87.0 ± 4.67)VS(87.6 ± 6.4)S,(6.44 ± 0.34)VS(6.46 ± 0.33)?g/mL,respectively].However,th ere were no stastistically significant differences(P>0.05).Bland-Altman analyse sho wed a good measurement reproducibility of quantitative perfusion and spectral para meters between two separate researchers(difference mean=0.04,0.03,-1.0,1.0 and-0.07,respectively).Conclusion:It is feasibility for CT perfusion combined spectral imaging in evaluati ng the hemodynamics of lower limb skeletal muscle in rabbit model.PART II CT perfusion combined spectral imaging in evaluating ischemia reperfusion injury in lower limb skeletal muscle of rabbitObjective To investigate the value of CT perfusion combined spectral imaging in evaluating ischemia reperfusion injury in lower limb skeletal muscle of rabbit.Method Tirty-five rabbits were included in the study.IR animals were divided into six groups according to different reperfusion time point:IR immediately group,IR 6 h group,IR 12h group,IR 18h group,IR 24h group,and IR 30h group(n=5,respectively).Sham-operated group was produced by exposing femoral artery without clamping and examined at corresponding postoperative 4h,10h,16h,22h,28h,34h.Blood supply of right lower limbs were clamped for 4h and recovered reperfusion,quantitative perfusion parameters,blood flow(BF),blood volume(BV),mean transit time(MTT),time to peak(TTP)and spectral parameters,energy iodine value(El)were obtained,the parameters ratio between the right side and left side(rBF,rBV,rMTT,rTTP,rEI)were calculated.All subjects were executed after CT examination.The thigh quadriceps fresh tissue samples were preserved for testing amount of malondialdehyde(MDA)and activity of superoxide dismutase(SOD)and pathological examination(HE).Compare CT perfusion parameter variations between groups and evaluate the correlation between parameters and MDA,SOD.Result rBF value of IR12h,18h,24h,30h group was significantly lower than that of sham-operated group[(0.78±0.07)vs(1.01±0.08),P=0.002;(0.70±0.08)vs(0.99±0.10),P=0.001;(0.64±0.07)vs(1.01±0.13),P=0.001;(0.65±0.09)vs(1.01±0.09),P=0.001].rBV value of IR12h,18h,24h,30h group was significantly lower than th at of sham-operated group[(0.85±0.08)vs(1.04±0.13),P=0.029;(0.75±0.09)vs(0.999±0.14),P=0.015;(0.67±0.09)vs(1.01 ±0.17),P=0.005;(0.68±0.09)vs(1.03±0.14),P=0.002].rEI value of IR18h,24h,30h group was significantly lower than that of sham-ope rated group[(0.72±0.07)vs(1.00±0.22),P=0.045;(0.70±0.08)vs(1.04±0.14),P=0.002;(0.71±0.09)vs(1.02±0.15),P=0.005].There are no statistical differences betwee n rMTT,rTTP value of IR0h,6h,12h,18h,24h,30h group and sham-operated gro up.rBF,rBV,rMTT,rEI values between six IR groups were significantly different(F=10.781,9.167,24.994 and 10.777,P=0.000,0.000,0.000 and0.000).rTTP values between six IR groups showed no significant difference((F=0.391,P=0.850).There were a good positive correlation between rBF,rBV,rEI values and SOD(r=0.638,P=0.000;r=0.592,P=0.001;r=0.575,P=0.001)and a good negative correlation bet ween rBF,rBV,rEI values and MDA(r=-0.401,P=0.028;r=-0.394,P=0.031;r=-0.410,P=0.024).Postoperative pathological examination showed there are no inflamma tion,myofibrosis and tissue swelling in sham group A,but a different levels of sev erity in experiment groups.There is a significant statistical difference of pathologica 1 grading in reperfusion group(F=14.273 P=0.000).In comparison of the each adj acent time point,a significant statistical difference was found between IR 12h and IR 18h(P=0.040)and no statistical significance between other adjacent groups.Conclusion 1)CT perfusion combined spectral imaging can accurately reflect the m icrocirculation change over time of lower limb skeletal muscle IR injury of rabbit.2)Parameters ratio rBF,rBV,rEI has a good correlation with biochemical markers(SOD,MDA).