Experimental Study On The Change Of Blood-brain Barrier Permeability After Traumatic Brain Injury Applying Dynamic Contrast Enhanced Magnetic Resonance Imaging

Objective:The purpose of this study is to investigate the value of dynamic contrast enhanced magnetic resonance imaging and serum S100β protein in the dynamic changes of blood-brain barrier permeability after traumatic brain injury.Methods:Sixty adult SD rats were randomly divided into injury group and sham operation group.The injury group was established by controlled cortical impact method.The sham operation group was used as control.MRI examination,serum S100p protein and Evans blue leakage The detection was performed at different time points(3h,1d,3d,7d,14d)after modeling,and 6 rats per time point.Magnetic resonance scanning was performed using a Philips 3.0T MR scanner and a 3.0T 8-channel laterally placed mouse coil.MRI scan sequences consist of conventional coronal T2WI sequences,DCE-MRI,and enhanced T1WI sequences of the rat’s head.After the scan,The DCE-MRI data were processed using the hemodynamic software-Omni Kinetics and The extended toft’s linear model was selected to calculate and measure the quantitative perfusion parameters of the brain lesion area and the contralateral mirror area.And The quantitative parameters includes the volume transfer constant(Ktrans),the rate constant(Kep),the extravascular extracellular volume fraction(Ve)and the fraction plasma volume(Vp).And further calculate the relative parameter value,the calculation formula:relative parameter value=damage side area/opposite side mirror area,obtain rKtrans,rVe,rKep,rVp.In addition,the concentration of S100β protein in the serum of rats at each time point was detected by ELISA,the EB dye in rat brain tissue was extracted by formamide solution,and the concentration of EB leakage was measured by ultraviolet spectrophotometer.The relative quantitative parameters of DCE-MRI(rKtrans,rVe,rKep,rVp),serum S100β protein and EB leakage between the injury group and the sham operation group were compared by t test,and the sum of the parameters at different time points was compared by rank sum test.The correlation between EB leakage and DCE-MRI relative quantitative parameters and serum S100βconcentration was analyzed by pearson correlation analysis;and the change of BBB permeability at each time point after trauma was observed.When the statistic P<0.05,the difference was statistically significant.Results:1.There were significant differences in the relative values of DCE-MRI perfusion parameters(rKtrans,rVe),serun S100β protein levels,and EB leakage at 1d,3d,and 7d between the injury group and the sham operation group(P<0.05).There was no significant difference between the two groups at other time points(P>0.05).When the rVp value was compared between the two groups,There was significant difference at the 7 day,and the difference was not statistically significant at other time points.The rKop value was compared between the two groups.There was significant difference at 3d and 7d.and the difference was not statistically significant at other time points.2,There were significant differences in the EB leakage in the injury group at different time points(P<0.05).The difference between the 3d group and the other time groups was statistically significant(P<0.05).It increased slightly at 3h after injury,lasted for 1d,and reached the peak at 3d,gradually declined at 7d and Dropped to normal level at 14 days3.The relative values of DCE-MRI perfusion parameters(rKtrans,rVe,rVp)in the injury group were statistically significant at different time points(P<0.05).There was no statistical difference in the time points of The relative values of DCE-MRI perfision parameters in the sham operation group(P>0.05).the trend of rK,rans and rVe values was consistent with the EB leakage.4.The serum S100β concentration in the injury group were statistically different at different time points(P<0.05).They increased slightly at 3 hours after injury and lasted for 1 day,The peak reached the peak at 3 days,gradually decreased at 7 days,and remained at a low level for 14 days.There was no significant difference in the amount of serum S100β in the sham operation group at each time point.(P>0.05)5.Correlation analysis showed a positive correlation between rKtrans value and EB leakage(r=0.712,P<0.01);there was a positive correlation between rVe value and EB leakage(r=0.544,P<0.01);There was also a positive correlation serum between S100β value and EB leakage(r=0.686,P<0.01).Compared with the serological S100β protein,the rKtrans value is more strongly correlated with the gold standard“EB leakage”.Conclusions:1.The rKtrans and rVe values could reflect the changes of BBB permeability after traumatic brain injury,and can be used as an effective index to evaluate the changes of BBB permeability.2.Serum S100β protein changes dynamically with time after traumatic brain injury,and to some extent,it could also reflect the change of BBB permeability.3.Compared with serum S100β protein,rKtrans could more accurately reflect the change of BBB permeability after traumatic brain injury.