Research And Clinical Application Of Diffusion Tensor Imaging In Evaluating Neurological Recovery After Ischemic Infarction

Part I DTI Features of normal adult brain tissue DTI imaging andparameters analysisObjective: To investigate the imaging features of normal adult braintissue through DTI protocol，Analyzing the characteristic of DCavg and FAof white matter and grey matter in different brain sites，and the repeatabilityof rebuilding DTT map.Method:10normal adult volunteer were collected, included fourmales and six females（mean age26.7±1.62years）, and received head DTIscans at three different time by3.0T MRI，the first and the second scanningwere performed at12:00pm and6：00pm at the same day，the thirdscanning was performed at any time after eight weeks. We rebuilt DCavgand FA map，meanwhile，and measured DCavg value and FA value incerebral peduncle，anterior limb of internal capsule，posterior limb ofinternal capsule，thalamus and Centrum Semiovale. Before calculating, thenormality test and homogeneity test of variances of data were conducted,ANOVA or nonparametric test was used through results. We mainly used t–test to compare DCavg value and FA value in left and right side in thesame site, different sites and in male and female. We also compared DCavgvalue and FA value collected at three different time. Analyzed therepeatability of DTT map rebuilding by rebuilding DTT maps with data ofthree different time scanning, p value<0.05was considered statisticallysignificant.Results：1DCavg value of left posterior limb of internal capsule is larger than thatin the right(p=0.038). Difference of DCavg value and FA value in differentsites were no statistically significant（p>0.05）.2There were not any difference between DCavg value of the five brainsites（p>0.05）, but FA value of different brain sites were different. Theorder of FA value of different brain site from large to small is：cerebralpeduncle>posterior limb of internal capsule>anterior limb of internalcapsule>centrum semiovale>thalamus.3Females DCavg value in cerebral peduncle is larger the that of males.4There is excellent repeatability when we rebuild the DTT map.Conclusion：1There is a difference in DCavg value in left and right sides of the samebrain site and between male and female. FA value of different brain sitesare different，FA value of cerebral peduncle attains maximum meanwhile,FA value of thalamus attains minimum. We should keep our mind on these differences.2DTI data collected from scannings at different time are stable，whichprovides theory basis for the application of DTI in normal adult brainresearch.3We rebuilt DTT maps with DTI data collected from scannings atdifferent time，and found that there is excellent repeatability when werebuild the DTT map, which could serve as intuitive method to investigatewhite fiber bundles and related disease. Part II DTI research of normal adult brain tissue age-relatedchangeObjective: To investigate the age-related DCavg value and FA valuechange of brain tissue between young people and elderly people through3.0T MRI.Method：15elderly people were collected as elderly group,includedeight males and seven females (mean age59.07±10.00）,15normal adultvolunteer as young group（mean age26.93±1.62）.The two groups receivednormal head MR scan and DTI scan by3.0T MRI. After we rebuilt theDCavg and FA map, DCavg value and FA value were collected in cerebralpeduncle，posterior limb of internal capsule，anterior limb of internal capsule，centrum semiovale and thalamus were measured. We analyzed thedifference of DCavg value and FA value between the two age group，andanalyzed the dependency between DCavg and FA with age, p value<0.05was considered statistically significant.Results：1DCavg value of right cerebral peduncle, right posterior limb ofinternal capsule and both sides of thalamus in elderly group were higherthan that of young group (p=0.024、0.048、0.038、0.022), with statisticalsignificance.2FA value of both sides of cerebral peduncle, right anterior limb ofinternal capsule, both sides of thalamus were higher than that of elderlygroup (p=0.012、0.024、0.015、0.017、0.038),with statistical significance.3DCavg value of cerebral peduncle and thalamus had positivecorrelation with age (r=0.44，p=0.01；r=0.54，p=0). FA value of cerebralpeduncle，anterior limb of internal capsule and thalamus had inversecorrelation with age (r=-0.60，p=0；r=-0.56，p=0；r=-0.40，p=0.03），with statistical significance. DCavg value of posterior limb of internalcapsule and centrum semiovale had positive correlation with age，differencewas not statistically significant.Conclusion：1We obtained the normal DCavg value and FA value of normal adultbrain tissue of different age group at3.0T MR scanning environment, provide reference data for the research of related disease.2The brain degeneration is a actively progress with the age，DTI couldreflect brain micro structure change. Specifically，DCavg value of elderlybrain is higher than that of young people. FA value of brain of youngadult is higher than that of elderly.3We use person correlation methods analyzed the correlation betweenDCavg value and FA value and age, and found that there are correlation andcertain regularity. DCavg value of brain has positive correlation with age.FA value of brain has inverse correlation with age. Part III DTI research of neural function recovery after ischemiainfarctionObjective: To investigate the neural function recovery after ischemiainfarction by DTI protocol, we regularly follow-up patients that suffered afirst acute ischemia infarction which have only one infarction, wequantitatively analyzed the change of DCavg value and FA value before andafter the rehabilitation treatment. At the same time，we observed DTT mapbefore and after the rehabilitation treatment to analyze the functionrecovery after ischemia infarction in order to provide DTI data for theclinical treatment. Method：This study collected31patients included seventeen malesand forteen females (mean age63.19±8.93years) who suffered a ischemiainfarction for the first time and treated with the rehabilitation treatment foreight weeks from November2011to December2013. All patiens met thestandard received normal MR scan and DTI scan befor and after therehabilitation treatment for eight weeks. We rebuilt the DCavg and FA map,measured DCavg value and FA value and compare the difference befor andafter the treatment. Two associate senior doctor were assigned to rebuildthe DTT map of white fiber bundles with DTI data before and after, andobserve the damage and recovery situation of white fiber bundles.Results:1FA value of infraction side increased after treatment for eight weeks（P<0.05），with statistical significance. DCavg value of infarction sideincreased after treatment for eight weeks（P>0.05），without statisticalsignificance.2FA value of uninjured side increased after treatment for eight weeks（P<0.05），with statistical significance. DCavg value of uninjured sideincreased after treatment for eight weeks（P>0.05），without statisticalsignificance.3rDCavg and rFA before treatment had inverse correlation with NIHSSscore. rDCavg and rFA after treatment had positive correlation with NIHSSscore. However，the results above had no statistical significance. 4There was not significant change of white fiber bundles of uninjuredside before and after treatment. However, compare the DTT map ofinfarction after treatment with before，white fiber bundles significantlydecreased.Conclusion：1DTI could reflect impairment and repairmen situation of nerve systemafter ischemia infarction by quantitative analysis. FA value increases withthe treatment illustrate that，the neural function is gradually recovered ininfarcts with the treatment.2FA value of uninjured side increases after treatment，this result mighthave correlation with the neural functional compensation in the uninjuredside，which is helpful for further investigation of neural function recovery.3Compare DTT map of uninjured side and infarction side before andafter rehabilitation treatment. We found that there is a progressiveirreversible damage in white fiber bundles. DTT is a visual observationmethod for observing neural function recovery after ischemia infarction.