The Study And Clinical Application Ofmagnetic Resonance Spectroscopy And Susceptibility Weighted Imaging After Traumatic Brain Injury

Part?Experimental dynamic study of proton magnetic resonance spectroscopy in rabbits with traumatic brain injuryObjective:To continuously measure changes of specific metabolite in the brain within 2 weeks after injury using proton magnetic resonance spectroscopy?¹H-MRS?in rabbit models of traumatic brain injury?TBI?,and to analyze the correlation between metabolite ratios in the brain of animals with different degrees of injury and Neurological Severity Score?NSS?scores within 24 hours after injury so as to explore the value of¹H-MRS in the diagnosis of TBI.Methods:Fifty Chinese rabbits were randomly assigned to control group?sham surgery;n=5?and injury group?n=45?.All rabbits received conventional MRI scan before TBI to exclude the rabbits with abnormal signals in the brain.In accordance with brain contusion method caused by Fenney free fall impact,different intensities of attack were chosen to hit the rabbit brain.According to NSS score,rabbits were divided into mild?NSS<15?,moderate?15?NSS?30?and severe?NSS>30?injury groups?n=15 per group?.MRI scan was conducted in each injury group at 1,6,24,48,168 and 336 hours after TBI.MRI images were scored by two imaging physicians who did not know the intensity of attack and NSS scores according to T₁WI and T₂WI images at 24 hours after TBI so as to analyze the correlation between NSS scores and MRI image scores.We observed the changes in N-acetylaspartate?NAA?,creatine?Cr?,choline?C ho?,lactic acid?Lac?and NAA/Cr,C ho/Cr ratios in metabolite at various time points,compared the differences in NAA/Cr and Cho/Cr ratios between injury group and control group,and analyzed the association between NAA/Cr ratio and NSS scores among injury groups at 24 hours after injury.Rabbits were sacrificed in batches following MRI scan at 24,168 and 336 hours after injury.The brain was obtained and sliced into sections.These sections were stained with hematoxylin and eosin.Pathological changes of injured brain tissue in each injury group were observed.Results:?1?Compared with the control group,NAA,Cho,and Cr peaks decreased in each injury group.No obvious Lac peak was seen at the injury site in the mild injury group.Lac peak was observed at the injury site in the severe injury group.Lac peak was detected at different stages after injury in 11 cases of the moderate injury group.?2?At 1 hour after injury,in the mild injury group?15/15?,moderate injury group?11/15?and severe injury group?3/15?,T1WI and T2WI images d id not show obvious abnormal signals.NAA/Cr ratio on the injury side decreased 12.79%,28.90%and 45.02%in the mild,moderate and severe injury groups,respectively.At 24 hours after injury,NAA/Cr ratio reduced 25.11%,39.81%and 51.18%in the mild,moderate and severe injury groups,respectively.Afterwards,NAA/Cr ratio increased in the mild and moderate injury groups,and reached a normal level at 336 hours,which did not show significant differences as compared with the control group.NAA/Cr ratio dropped to a maximum of 54.97%at 48 hours,and then gradually increased in the severe injury group.However,NAA/Cr ratio was still lower than the normal level at 336 hours in the moderate and severe injury groups,and 87.20%and66.82%of that in thecontro l group.?3?C ho/Cr ratio on the injury side in the mild,moderate and severe injury groups decreased 10.86%,15.94%and 34.78%,respectively at1 hour after injury,and decreased 24.63%,29.71%and 42.02%,respectively at 6 hours.Cho/Cr ratio increased at 24 hours in the mild,moderate and severe injury groups.C ho/Cr ratio was higher in the mild and moderate injury groups than in the control group at 168hours.At 336 hours,C ho/C r ratio in the mild,moderate and severe injury groups recovered to 110.86%,121.01%and 94.92%of that of the control group,respectively.?4?After TBI,NAA/Cr levels were significantly negatively correlated with NSS scores.Conventional MRI image scores were lightly positively correlated with NSS scores.?5?The results of MRS in each injury group at different stages after injury were consistent with pathological changes.Conclusion:?1?¹H-MRScan noninvasively dynamically detect the metabolic changes of brain tissue after TBI.?2?¹H-MRS can detect abnormal changesin the injur ed brain earlier than conventional MRI.Among them,NAA/Cr is most sensitive.Compared with conventional T1WI and T2WI images,¹H-MRS is more accurate in judging the extent of TBI damage.?3?After local brain injury,the changes of NAA/Cr and Cho/Cr ratios and the appearance of Lac peak reflect the severity of brain injury to some extent,and have positive significance for early judging the extent of TBI and evaluating prognosis.?4?After local injury,NAA/Cr ratio recovers to different degrees,suggesting that brain tissue damage can recover within a certain range,and the degree of recovery may be associated with the extent of brain injury.The lighter the damage degree is,the faster the recovery of NAA/Cr ratio will be,and the bigger the recovery rate will be.Part?Clinical dynamic study of susceptibility weighted imaging and magnetic resonance spectroscopy after traumatic brain injuryObjective:To evaluate the correlation of image data with Glasgow Coma Scale?GCS?and Glasgow O utcome Scale?GOS?scores,and to e xplore the value of magnetic resonance spectroscopy?MRS?and susceptibility weighted imaging?SWI?in assessing injury severity and predicting prognosis after traumatic brain injury?TBI?by dynamically detecting and analyzing SWI images in the acute stage and MRS images at different stages in TBI patients.Methods:We collected 57 TBI patients as TBI group and 30 age-and gender-matched healthy volunteers as control group.All subjects received SWI,MRS and conventional MRI scans.In accordance with GCS scores within 24 hours after TBI,patients were assigned to mild injury group?GCS score=13–15;n=22?,moderate injury group?GCS score=9–12;n=19?and severe injury group?GCS score?8;n=16?.In accordance with GOS scores at 6 months after TBI,patient s were divided into good prognosis group?GOS score=5;n=24?,average prognosis group?GOS score=4;n=16?and poor prognosis group?GOS score=3;n=17?.TBI patients received SWI scan in the acute stage.We recorded the number of regions involved in hemorrhagic foci,number and area of the hemorrhagic foci,analyzed the differences among injury groups,and analyzed the correlation between SWI data and GCS scores within 24 hours after TBI.We detected MRS data in different stages in the control and TBI groups,observed the change law of NAA/Cr and Cho/Crratios,compared the differences in MRS data between control and TBI groups,as well as among injury groups,and analyzed the correlation between NAA/Cr ratio and GCS scores in the acute stage of TBI,and the correlation between NAA/Cr ratio and GOS scores at 3 months after TBI.Results:?1?The number of regions involved in hemorrhagic foci,number and area of the hemorrhagic foci revealed by SWI were significantly different among mild,moderate and severe injury groups?P<0.05?.?2?The number of regions involved in hemorrhagic foci,number and area of the hemorrhagic foci revealed by SWI were negatively correlated with GCS scores within 24 hours after TBI and GOS scores within 6months after TBI.Area of the hemorrhagic foci revealed by SWI was highly associated with GCS scores.?3?NAA/Cr ratio persistently reduced within 1 month after TBI,and increased at 3 months in the mild and moderate injury groups.NAA/Cr ratio did not increase within 3 months after TBI in the severe injury group.C ho/Cr ratio increased after TBI.In particular,the increase in C ho/Cr ratio was highest in the severe injury group.?4?NAA/Cr ratio was positively correlated with GCS scores within 1 week after TBI.?5?NAA/Cr ratio was positively correlated with GOS scores at 3 months after TBI.Conclusion:?1?The number of regions involved in hemorrhagic foci,number and area of the hemorrhagic foci revealed by SWI can independently reflect the degree of TBI.The area of hemorrhagic foci is the most reliable index to judge the extent of TBI.?2?The number of regions involved in hemorrhagic foci,number and area of the hemorrhagic foci revealed by SWI can be used as an effective predictor for prognosis of TBI.The area of hemorrhagic foci has greatestdiagnostic value.?3?The change laws of NAA/Cr and Cho/Crratios after TBI indirectly reflect pathophysiological changes in brain tissue after injury.NAA/Cr ratio recovery after injury can be regarded as a marker of recoverable injury.?4?NAA/Cr ratio can be used as a reliable index for judging the extent of TBI.?5?At 3 months after TBI,NAA/Cr ratio can be used as an effective predictor for prognosis.