The Preliminary Study Of Multimodal MRI In The Assessment Of Traumatic Brain Injury,Post-traumatic Epilepsy And Depression

Chapter One The experimental study of multimodal MRI in the assessment of injury severity after traumatic brain injuryObjective: The aim of this study was to evaluate the value of multimodal MRI(including T2 W, susceptibility weighted imaging（SWI）, diffusion kurtosis imaging（DKI） and dynamic contrast-enhanced magnetic resonance imaging（DCE-MRI） and its quantitative coefficient(K^trans)) in the assessment of the different injury severity after traumatic brain injury（TBI）.Materials and methods:Based on weight-drop device, we used the different impact force（30×20 cm*g, 60×20 cm*g, or 90×20 cm*g） to induce mild, moderate, or severe TBI, respectively. One day after TBI, we used veterinary coma scale system（VCS） to evaluate the impaired neurofunction after TBI. Meanwhile the multimodal MRI（including T2 W, SWI, DKI and DCE-MRI） was performed to each experimental rabbit. Then the lesion volume on T2 W and the hemorrhage volume on SWI was calculated. More important, the values of MD,MK and K^trans in every ROIs（including ipsilateral cortex, ipsilateral hippocampus, ipsilateral thalamus, contralateral hippocampus and contralateral thalamus） was calculated. We analyzed the difference of VCS, lesion volume and hemorrhage among the four study groups. And also the difference of MD, MK and K^trans in every ROIs among the four study groups was analyzed.Results: With the increase of impact force, the VCS score was gradually reduced（all p<0.01） and the lesion volume increased（all p<0.01）. The hemorrhage volume in the severe TBI group tended to be greater than moderate TBI group（p=0.071）, the hemorrhage volume in the moderate injury group was larger than mild TBI group（p<0.01）. The K^trans values of the ipsilateral cortex in all TBI groups were all larger than sham group（p<0.001）. With the increase of impact force, the K^trans values of the ipsilateral cortex was gradually increased（p<0.001）. In the ipsilateral hippocampus, the K^trans values in the severe TBI group was higher than moderate TBI group（p=0.001） and the moderate TBI group was higher than mild TBI group（p<0.001）, no difference was found of K^trans value between mild TBI group and sham group（p=0.918）.In the ipsilateral thalamus, the K^trans value in the severe TBI group was higher than moderate, mild and sham groups（all p<0.001）, no difference was found among the moderate, mild and sham groups（all p>0.05）.In the contralateral hippocampus and thalamus, no difference was found among these four groups（sham, mild, moderate and severe）（all p>0.05）.In the ipsilateral cortex, the MD values in the severe TBI group was higher than moderate TBI group（p=0.016） and the moderate TBI group had a trend to be higher than mild TBI group（p=0.096）, the MD values in the mild TBI group was higher than sham group（p=0.01）.In the ipsilateral hippocampus, the MD values in the severe TBI group was higher than moderate TBI group（p=0.009） and the moderate TBI group was higher than mild TBI group（p<0.001）, no difference was found between mild TBI group and sham group（p=0.278）. In the ipsilateral thalamus, contralateral hippocampus and contralateral thalamus, no difference of MD values was found among these four groups（sham, mild, moderate and severe）（all p>0.05）.In the ipsilateral cortex, ipsilateral hippocampus and thalamus, the MK value in all TBI groups were lower than sham group（all p<0.01）,and more important, with the increase of impact force, the MK values of these ROIs were gradually decreased（all p<0.05）. In the contralateral hippocampus and thalamus, the MK values in the severe TBI group were lower than moderate TBI group（all p<0.01） and the moderate TBI group were lower than mild TBI group（all p<0.01）, no difference of MK values was found between mild TBI group and sham group（p=0.646,0.5 respectively）.Conclusions: The multimodal MRI could evaluate the injury severity and the abnormalities after TBI quantitatively and comprehensively.DKI could detect the abnormal areas which appeared normal on other sequences.Chapter Two The experimental study of diffusion kurtosis imaging combined with dynamic contrast-enhanced magnetic resonance imaging in the prediction of post-traumatic epilepsyObjective: To explore the value of diffusion kurtosis imaging（DKI） combined with dynamic contrast-enhanced magnetic resonance imaging（DCE-MRI） in the prediction of post-traumatic epilepsy（PTE）.Materials and methods:We used a modified weight drop device to induce the traumatic brain injury（TBI）.38 rabbits were randomized divided into two groups, TBI group（n=30）, sham group（n=8）. The DKI and DCE-MRI were performed at 1 day after experimental TBI. And the PTE was investigated within 3 months after TBI. According the PTE, the TBI group was divided into two groups, that is PTE group and Non-PTE group. The differences of MK values and K^trans values in all ROIs（including ipsilateral cortex, ipsilateral hippocampus, ipsilateral thalamus, contralateral hippocampus and contralateral thalamus） among these three groups was analyzed. After the follow-up,the experimental animals were sacrfied for the Nissl staining.Results: In TBI group, 2 experimental rabbits died. Of the 28 rabbits in TBI group, post-traumatic seizure（PTS） was found at least once in 8 rabbits and these 8 rabbits were classified as the PTE group. In the ipsilateral cortex, the K^trans values in PTE and Non-PTE groups were both higher than sham group（all p<0.001） and the K^trans values in PTE group was higher than Non-PTE group（p<0.001）. In the ipsilateral hippocampus, the K^trans values in PTE was higher than Non-PTE group and sham group（all p<0.001） and no difference was found of K^trans values between Non PTE group and sham group（p=0.907）.In the ipsilateral thalamus, contralateral hippocampus and thalamus, no difference was found of K^trans value among these three groups（PTE, Non-PTE and sham group）（all p>0.05）.In the ipsilateral cortex, the MK value in PTE and Non-PTE groups were both lower than sham group（all p<0.001） and MK value in PTE group was lower than Non-PTE group（p<0.001）.In the ipsilateral thalamus, the MK value in PTE and Non-PTE groups were both lower than sham group（all p<0.001） and MK value in PTE group was lower than Non-PTE group（p<0.001）.In the ipsilateral hippocampus, the MK value in PTE and Non-PTE groups were both lower than sham group（all p<0.001） and MK value in PTE group was lower than Non-PTE group（p<0.001）. In the contralateral hippocampus, the MK value in PTE and Non-PTE groups were both lower than sham group（p<0.001,p=0.002,respectively） and MK value in PTE group was lower than Non-PTE group（p<0.001）.In the contralateral thalamus, the MK value in PTE and Non-PTE groups were both lower than sham group（all p<0.001）, but no difference was found of MK value between PTE group and Non-PTE group（p=0.721）. The number of neuronal cells in contralateral hippocampus revealed by Nissl staining in PTE group was less than Non-PTE group（p=0.006）.Conclusions: The early breakdown of blood-brain barrier in ipsilateral cortex and hippocampus after TBI and the damage severity in the ipsilateral cortex, ipsilateral hippocampus, ipsilateral thalamus and contralateral hippocampus were correlated with PTE.Chapter Three The study of susceptibility weighted imaging combined with diffusion kurtosis imaging in the evaluation of encephalomalacia accompanied with epilepsy after traumatic brain injuryObjective: Epilepsy remains one of the most intractable complications of encephalomalacia resulted from traumatic brain injury（TBI）. This study aimed to predict epilepsy objectively by analyzing the imaging features for epilepsy with advanced magnetic resonance imaging（MRI）.Materials and methods: From 2012 to 2014, 252 patients（Male:145; Female:107; Average age: 38.03±13.31） with TBI were prospectively enrolled in the study, Participants were ascertained at the time of injury from the emergency room（ER）. Inclusion criteria were:（i） witnessed closed head trauma（motor vehicle accidents, falls, struck by construction debris）;（ii） initial evaluation at a clinic and or emergency room with findings consistent with TBI(Glasgow Coma Score（GCS〉9） and no neurologic deficits;（iii） follow-up post-injury should be more than1 year.（iv） abnormal encephalomalacia on conventional imaging. Exclusion criteria were（i） history of previous TBI;（ii） other neurological disease;（iii） history of illicit drug use substance abuse. At 1 year follow-up, all participants were divided into two groups: epilepsy group and non- epilepsy group. All of them underwent MRI including conventional imaging, SWI and DKI sequence as well. The lesion volume, the iron deposition, and the MD and MK values around the lesions were calculated. The ANOVA model was used to compare these values between the two groups using the Fish-LSD test（two sample T test comparison）. P values less than 0.05 were considered to represent statistically significant differences by using SPSS 16.0.Results: In total, 6o epilepsy patients and 91 non- epilepsy patients were reported in the study. All patients underwent MRI scanning. Baseline characteristics showed no significant difference involved GCS scores and lesion volume between the two groups. Iron deposition is significantly higher in the epilepsy group than that in the non-epilepsy group（p<0.05）. No significant difference was found in encephalomalacia. MD values showed no significant difference between the two groups, while MK values showed significant difference（ p<0.05）.Conclusions: The present study shows that evaluating epilepsy as a consequence of encephalomalacia in patients with TBI by using advanced MRI is of interest and importance. Ion deposition could evaluate encephalomalacia and microstructure changes around the lesions, suggesting a possible role for iron accumulation in the prediction of epilepsy in these patients.Chapter Four Microbleeds on susceptibility-weighted MRI in depressive and non-depressive patients after mild traumatic brain injuryObjective: To analyze the correlation between microbleed detected by susceptibility-weighted imaging（SWI） and the newly-developed depression after mild traumatic brain injury（TBI）.Materials and methods: 165 patients with closed TBI and normal finding at CT and conventional MRI were included in this study. All patients underwent MRI including conventional MR sequences and SWI. The number and volume of microbleed lesions were semiautomatically outlined and manually counted. All patients were followed up with the Diagnostic and Statistical Manual of Mental Disorders（DSM-IV） within 1 year after TBI. The difference in microbleed on SWI was compared between the depressive and nondepressive groups.Results: The depressive group had a higher rate of abnormality on SWI than did the nondepressive group（p <.001）. Among patients that had exhibited microbleed lesions, the number and volume of lesions was greater in the depressive group than the nondepressive group（both p <.001）. These differences in numbers and volume of lesions were found only at the frontal, parietal and temporal lobes（all p <.001）. Among patients that had exhibited microbleed lesions, the number and volume of lesions in other areas was not significantly different between the depressive and nondepressive groups（all p >.05）.Conclusions: SWI was more sensitive in the detection of microbleed after mild TBI. The microbleed lesions located at the frontal, parietal and temporal lobes were correlated with depression after TBI.