Preliminary Study Of Normal Brain Structure Of Han And Tibetan Adults With DTI And DTT Imaging In3T MRI

Objective: To study the anisotropy and diffusion characteristics as well as thefibers of the normal Han and Tibetan adults with DTI and DTT technology in3TMRI,to explore the relationship between the FA value and altitude,and tosee if there is some difference between nations.Methods:120cases of Han and Tibetan people from different altitudes（living in the current altitude for more than1year） were chosen. All the caseswere divided into6groups according to the altitude,GroupA:Han people from2200m to3000m,Group B:Tibetan people from2200m to3000m,GroupC:Han people from3000m to4000m,Group D:Tibetan people from3000m to4000m,Group E:Han people from more than4000m,Group F:Tibetan peoplefrom more than4000m,there were20cases in every group,and the range ofaverage age of every group is from20to55. The equipment was PhilipsAchieva3.0TX multi-source emission superconducting MRI scanner，axis,scanning sequence: TlWI, T2WI, FLAIR, DWI and DTI. the sequence ofsingle excitation spin echo planar imaging （EPI） was adopted in the scanning.to get the FA and ADC value of the genu and splenium of corpus callosum、bilateral anterior limbs and posterior limbs of internal capsules、bilateralexternal capules、frontal white matter、cingulum、centrum semiovale、bilateral caudate nucleus head、lenticular nucleus and thalamus respectively and to perform statistical analysis. The Fiber Track soft ware was used to get3-dimensional fiber imaging.Results:1. There was no difference between the FA and ADC value of theright and left cerebral hemisphere of the Han and Tibetan people fromdifferent altitude. And there was no sexual difference.2. The FA value of the white matter was higher significant than the FA valuesof gray matter nuclei. The FA value of the corpus callosum was the highest inall the white matter, followed by posterior limbs of internal capsule andcingulate, the genu of corpus callosum, anterior limbs of internal capsules,centrum semiovale, frontal white matter, and the FA value of the externalcapsule was the lowest. The FA value of the thalamus was the highest in graymatter nuclei, followed by head of caudate nucleus，and the FA value of thelenticular nucleus is the lowest. There were some difference between the ADCvalue of some white matter and gray matter,the reference range of ADC valueis （0.692-0.941）(10^-3mm²/s).3. With the altitude increasing, the subcortical ischemic focal occurrence rateincreasing, and most of them located in the frontal cortex, but there was nodifference in anisotropic and diffusion in the frontal white matter.There wassome statistical difference between the FA value of the knee of the corpuscallosum and head of the caudate nucleus of Tibetan people from2200m-3000m and3000m-4000m.4. Comparison between Han and Tibetan people:The FA value of the caudate nucleus of the two nation from3000-4000m had statistical difference,and theADC value of the centrum semiovale and the had statistical difference.（p=0.028, P=0.006）5. The different color in the FA color-coded graph and fiber graph can helprecognizing the tracts and line direction of the fibers.Conclusion: with the altitude increasing, the subcortical ischemic focaloccurrence rate increasing,the rate was15%、32.5%、47.5%respectively,especially in the frontal lobes.but there was no difference in anisotropic anddiffusion in the frontal white matter.The anisortropy of the caudate nucleus ofthe two nation from3000-4000m had statistical difference，There was somestatistical difference between the anisortropy of the head of the caudatenucleus,and the diffusion charactic of centrum semiovale and frontal lobe.theloubus of Tibetan people from2200m-3000m and3000m-4000m.Theresearch can also provide reference range for normal adults from more than2200m in brain DTI imaging.