Diagnostic Value Of Gemstone Spectral Imagine Combined With CT Perfusion Imaging In Lower Limb Ischemia And Necrotic Skeletal Muscle-A Preliminary Study

Part Ⅰ A feasibility study of gemstone spectral imaging combined with CT perfusion imaging in skeletal muscle of lower limbsObjective:To investigate the feasibility of gemstone spectral imaging combined with CT perfusion imaging in evaluating the hemodynamics of lower limb skeletal muscle in rabbits.Methods:14 New Zealand white rabbits were randomly numbered.GE Revolution CT was used to scan the rabbits with craniocerebral perfusion mode.The scanning range was from the lower abdomen to the hind limbs.Two radiologists independently completed image post-processing and data acquisition at the workstation,and obtained blood flow(BF),blood volume(BV),mean transit time(MTT),and time to peak(TTP),Iodine concentrations(ICs),effective atomic number(Eff-Z),spectrum attenuation curve(SAC)and other perfusion and spectrum parameters,and Compared quantitative parameters between the thigh and the calf.Bland-Altman consistency analysis was used to evaluate the repeatability of the two physicians’ measurements.Results:(1)The lower limb anatomy of rabbit was similar to that of human body,and the thigh artery has many important branches;The perfusion images showed that rabbits has abundant blood supply and uniform distribution in lower limbs.(2)The quantitative parameters between the thigh and the calf were as follows:BF were 5.51ml/min/100g±1.38 and 5.43ml/min/100g±1.22,BV were 1.67ml/100g±0.52 and 1.59ml/100g±0.62,MTT were 17.33s±2.11 and 18.11 s±0.35,TTP were 78.63s±2.46 and 79.63s±3.96,ICs were 6.03 100ug/cm3±1.21 and 5.67 100ug/cm3±1.35,Eff-Z were 8.38±0.35 and 7.791±0.95.The BF,BV and ICs for the thigh group were not significantly higher than that for calf group(p>0.05).The MTT、TTP and Eff-Z for the calf group were not significantly higher than that for thigh group(p>0.05)(3)Bland-Altman analysis showed a good measurement reproducibility of quantitative parameters between two separate readers(difference mean=-0.1,-0.03,-0.17,-0.04,-0.05,-0.3).Conclusion:It was feasible to evaluate the hemodynamics of lower limb skeletal muscle in rabbits by gemstone spectral imaging combined with perfusion imaging.Part Ⅱ The application of gemstone spectral imaging combined with perfusion imaging in the lower limb ischemia and necrotic skeletal muscleObjective:To investigate the dynamic changes of parameters of CT perfusion imaging of chronic ischemic necrosis of lower extremities and its value in differential diagnosis of ischemia and necrosis of lower extremities.Methods:Sixteen male New Zealand rabbits were randomly numbered.Hindlimb ischemia model was induced in right hindlimbs of 16 New Zealand white rabbits by excision of femoral artery and the branch.The right hindlimb was the surgical side group,and the left hindlimb group was the healthy side group.Before and 5d,2w,4w,6w,8w after the model establishment,spectral CT perfusion scan was performed on models respectively.All the data were sent to the workstation and the perfusion curve and the parameters(BF,BV,MTT,TTP,ICs,EFF-Z)were analyzed.At 8th week,all the models were killed to make a pathological examination.According to the results,they were divided into the ischemia group and the necrotic group.Receiver operating characteristic cures were generated to determine parameters for optimizing sensitivity,specificity and accuracy in this study.Results:(1)BF and ICs of the right hindlimbs were significantly lower than that of the left at 5d,6w and 8w(P<0.05).BV of the right hindlimbs were significantly lower than that of the left at 5d and 8w(P<0.05).There was no significant difference of MTT,TTP and EFF-Z among the two hindlimbs at each time(P>0.05).(2)BF,BV and ICs of the ischemia group was significantly higher than that of the necrotic group at 8th week(P<0.05).(3)The SAC of the necrotic group was under that of the ischemia group,and there was no significant difference of the slope of SAC among the two groups(P>0.05).(4)ROC curve analysis found that BF,BV and ICs were more accurate in identifying skeletal muscles in the ischemic and necrotic groups.Conclusion:Gemstone spectral imaging combined with perfusion imaging can accurately demonstrate the dynamic process of chronic ischemia and necrosis of the lower limbs.When BF<2.34,BV<0.85,ICs<2.55,skeletal muscle could be distinguished between ischemic group and necrotic group,and the accuracy of BV was the highest.