Preliminary Application Of DKI In Motor Dysfunction Recovery In Patients With Subcortical Focal Cerebral Infarction

Objective:1.To investigate the characteristic changes of secondary degeneration of the corticospinal tract(CST)and cerebral cortex remodeling after cerebral infarction and its potential significance for the recovery of neurological functions with diffusion kurtosis imaging(DKI)prospectively.2.Dynamically observed the changes of the DKI parameters of CST and cerebral cortex after cerebral infarction quantitatively.Combined the clinical motor function scores,to explore the feasibility of DKI in detecting secondary degeneration of CST,cerebral cortex remodeling and predicting the prognosis of patients.Materials and Methods:19 patients experienced subcortical stroke subcortical focal cerebral infarction underwent routine MRI and DKI examinations and evaluations with the National Institutes of Health Stroke Scale(NIHSS),the Barthel Index(BI),Modified Ranking Scale(mRS)within 72 hours,at 4 weeks and 12 weeks respectively.19 age-and gender-matched healthy volunteers were recruited as controls while they underwent DKI only once.DKI and DTI data was obtainedat the same time.MK map,AK map,RK map,FA map,MD map were obtained by functool post-processing software.According to the definition of the region of interest(ROI)based on the original map of DKI,the the parameter values of the central anterior cortex,the pedunculus cerebri,and the pons were manually measured.t-test was employed for the group comparison.The repeated measures analysis of variance was used for Intra-group comparison of DKI,DTI statistics and neurological functions scale at different time-points.The Spearman Correlation Analysis Method was used to compare the relationship between the change percentage(pX)of neurological function scores and the parameters in the acute phase to 12 W as well as the mirror side parameter ratio(rX)in the acute phase and the neurological function score at 12 W.All calculations were performed using SPSS software version 17.0.Results:1.Compared with the normal control group,the values of MK,AK,and MD of the central anterior cortex away from the infarct within 72 hours,at 4 weeks and 12 weeks of the cerebral infarction were all increased;among them,MK and AK in the affected side were significantly increased in the acute phase(P<0.05),and the affected MD was significantly increased at all the time points(P<0.05).In the acute phase,the MK and AK were higher in the affected side than the mirror side,whereas after 4W,and AK was lower than the mirror side at 12 W with statistical significance(P<0.05).In the selected of two layers of the corticospinal tract(the pedunculus cerebri and the pons),the MK of both sides of the pedunculus cerebri within 72 hours,at 4 weeks and 12 weeks were higher than the normal control group,but were lower in the pons,the difference was statistically significant(P < 0.05).The MK of the pedunculus cerebri within 72 hours was higher than the mirror side,and the difference was statisticallysignificant(P<0.05).The RK of both sides of the pedunculus cerebri within 72 hours,at 4 weeks and 12 weeks were higher than the normal control group,but were lower in the pons,the difference was statistically significant(P<0.05).The RK in the affected side of the pedunculus cerebri within 72 hours was higher than the mirror side,and the difference was statistically significant(P<0.05).The AK in the affected side of the pedunculus cerebri within 72 hours,at 4weeks and 12 weeks were higher than the normal control group,but were lower in the pons,the difference was statistically significant(P<0.05).The FA in the affected side of the pedunculus cerebri and the pons within 72 hours,and both side of the pedunculus cerebri and the pons at 4 weeks and 12 weeks were lower than the normal control group,the difference was statistically significant(P<0.05).The FA of the pedunculus cerebri at three time-points and that of the pons within 72 hours were lower than the mirror side,and the difference was statistically significant(P<0.05).From acute phase to 12 W,the MD of ipsilateral central gyrus increased gradually,and the FA of the pedunculus cerebri and the pons gradually became smaller,and the MK of pons gradually decreased,which all showed a significant time effect(p<0.05).2.From the acute phase to 12 W of the focal cerebral infarction,the pMK in the ipsilateral central anterior cortex showed significant negative correlation with patients’ pmRS(r=-0.690,p=0.009).The pMD in the ipsilateral central anterior cortex showed significant negative correlation with patients’ pNIHSS and pmRS(r=-0.610,-0.623;p=0.027,0.023).The pMK of the ipsilateral pedunculus cerebri was significantly and negatively correlated with the patient’s pNIHSS(r =-0.570,p = 0.042).There was a significant positive correlation between the pMK in the ipsilateral pons and pBI(r=0.676,p=0.011).There was a significant positive correlation between the rMK,rRK of ipsilateralpedunculus cerebri in acute phase and the NIHSS scores at 12W(r=0.693,0.724;p=0.009,0.005).There was no significant correlation between the ratio of parameters of the cerebral cortex and the pons in the acute phase and the clinical score of 12 W.Conclusion:1.The motor cortex microstructures of both sides were changed within 72 hours and at 12 weeks after subcortical focal cerebral infarction,and Secondary degeneration of the corticospinal tract persisted,and could be quantitatively assessed by DKI,which was more accurate and reliable than traditional diffusion imaging.2.The cerebral cortex remodeling after cerebral infarction may promote the recovery of neurological functions,and secondary degeneration of CST may hinder the recovery of neurological functions.3.The MK and MD of the central anterior cortex in the affected side had the strongest correlation with the prognosis of clinical neurological function.The MK and RK of corticospinal tract in the affected side had the strongest correlation with the prognosis of clinical neurological function.They could be served as new imaging parameters to early observe the secondary degeneration of CST and cortical remodeling,and could indirectly reflect the patients’ prognosis and guide clinical treatment.