The Study Of Mild Traumatic Brain Injury Using Diffusion Kurtosis Imaging And Arterial Spin Labeling

Purpose To investigate the changes of brain struction and cerebral blood flow(CBF)in mild traumatic brain injury(m TBI)patients by using diffusion kurtosis imaging(DKI)and pusled arterial spin labeling(PASL),and to explore the relationship between these image changes with post concussion symptoms severity.Materials and Methods20 m TBI patients,15 normal controls(NC)were inculded in this study.For m TBI patients,they were all in the acute phase(less than 3 days)and their conventional CT and conventional MRI scans had no positive lesion;Glasgow Coma Scale(GCS)scores were all 15.In this study,we further divided m TBI patients into two groups,SWI(-)group and SWI(+)group,depending on if there was the sign of axonal injury on SWI images.All data were acquired on a Siemens 3 T MR scanner using a 8-channel head coil.Scanning sequences included T1 MPRAGE,T2WI,SWI,DKI,PASL.Before scanning,the severity of postconcussion symptoms were measured using the Rivermead Postconcussion Symptoms Questionnaire(RPSQ).The process of analysis of DKI data were as follows:(1)The process of analysis of whole brain white matter.Firstly,we got the maps of DKI parameters(FA,MD,MK,AK,RK)using Diffusional Kurtosis Estimator(DKE)software;Secondly,FSL was used to conduct the Tract Based Spatial Statistics(TBSS)analysis and the correlation analysis between DKI parameters and RPSQ score.Age was used as covariate.p < 0.05 means statistical significance.(2)The process of analysis of bilateral thalami.Region of interest(ROI)analysis was be used to study bilateral thalami,and we defined bilateral thalami based on wfu pickatlas.The calculation of parameter values based on MRICRON software.The process of analysis of PASL data were as follows: Firstly,the r CBF maps can generate automatically after scanning;Secondly,we defined ROI areas(bilateral frontal,parietal,temporal,occipital lobes and bilateral thalami)in AAL using wfu pickatlas toolkit;Thirdly,calculaing r CBF value for each ROI using MRIcro N software.The values of r CBF for ROI areas were compared between NC,SWI(-)and SWI(+)groups using analysis of variance(ANOVA)and age was used as covariate.The post hoc test utilized the Bonferroni method.The correlations between r CBF values and RPSQ score were assessed using Spearman correlation coefficients.Agewas used as covariate.p < 0.05 means statistical significance.Results The results of DKI data:(1)White matter analysis: for SWI(-)and NC groups,SWI(-)group showed increased FA、decreased MD、increased MK、increased AK and increased RK in some WM regions;for SWI(+)and NC groups,SWI(+)group showed decreased FA、increased MD、decreased MK、decreased AK and decreased RK in some WM regions;for SWI(-)and SWI(+)groups,SWI(+)group showed decreased FA、increased MD、decreased MK、decreased AK and decreased RK in some WM regions;No correlation was found between DKI data and RPSQ score.(2)Bilateral thalami analysis: for SWI(+)and NC group,SWI(+)group showed increased MK in right thalamus(non-Bonferroni method,p=0.043).No change was found in any DTI parameter.No correlation was found between changed DKI data and RPSQ score.The results of PASL data: For SWI(-)and NC groups,SWI(-)group showed decreased r CBF value in left occipital lobe(p=0.021);For SWI(+)and NC groups,SWI(+)group showed decreased r CBF value in left frontal lobe(p=0.047)、 right occipital lobe(p=0.011)、 right temporal lobe(p=0.033)and right parietal lobe(p=0.020);For SWI(+)and SWI(-)groups,SWI(+)group showed decreased r CBF value in right temporal lobe(p=0.028);The values of r CBF in left frontal lobe negatively correlated with RPSQ score(r=-0.598 p=0.007).Conclusion1.DKI parameters showed changes in some areas of white matter in m TBI patients,and showed more abnormal areas in SWI(-)group than findings by using DTI,so it may be sensitive to detecting white matter changes in axonal injury in m TBI patients.2.MK changed in right thalamus but DTI parameters showed no change,so MK is sensitive to detecting grey matter,and thalami may be involved after m TBI.3.PASL showed the decreased CBF level in the brain of m TBI patients and this change correlated with RPSQ score,so it may be one of the contributing factors for m TBI patients’ clinical symptoms.