The Clinical Application And Research Of Diffusion Tensor Imaging In Cerebral Ischemic Stroke Corticospinal Tract Injury At 3.0T MR

Part Ⅰ The application research of MR diffusion tensor imaging in cerebral ischemic stroke corticospinal tract injury and clinical prognosisObjective:To study the evolution of MR diffusion tensor imaging(DTI)parameters in different stages of cerebral infarction lesions,including apparent diffusion coefficient(ADC)and fractional anisotropy(FA),relative apparent diffusion coefficient(rADC),relative fractional anisotropy(rFA),the decreased percentage of FA value(dFA).And to explore the relationship of diffusion tensor parameters and corticospinal tract(CST)injury scores with the severity of clinical symptoms in cerebral infarct patients,in order to evaluate the clinical prognosis early.Methods:All fifty patients met the inclusion criteria with cerebral infarction in during the course of different stages were proceed regular head MRI scans and whole brain DTI data acquisition,ADC and FA values were measured in infarct lesions and control areas respectively,then calculated the rADC、rFA、dFA value and performed three-dimensional reconstruction of bilateral corticospinal tract using DTT.The change rule of MR diffusion tensor parameters in cerebral infarction lesions during the course of different stages and the correlationship of diffusion tensor parameters rADC、rFA and CST injury scores with the NIHSS score before examine and 30 days,90 days after the onset of ADL scores were analyed respectively.Results:1.During the course of disease in acute,sub-acute and chronic stage,the FA values in infarct lesions decreased gradually,but the ADC value in infarct lesions increased.The FA value in the infarction areas were significantly lower than control areas in acute,sub-acute and chronic stage(P<0.05);The ADC value in infarction areas were significantly lower than control areas in acute,sub-acute stage(P<0.05).However,The ADC value in infarction areas were almost the same level with control areas in chronic stage,there was no significant difference(P>0.05).2.The rFA values of infarct lesions decreased progressively and the dFA value of infarct lesions increased progressively,the rADC value of infarct lesions increased slowly during the course of disease.The rFA value of the infarction areas in chronic stage were lower than acute stage(P<0.05),the dFA value of the infarction areas in chronic stage were higher than acute stage(P<0.05);The rADC value of the infarction areas in chronic stage were higher than acute,sub-acute stage respectively(P<0.05).3.The rADC/rFA of the infarction areas with the NIHSS scores and 30 days,90 days after the onset of ADL scores was no significant differences(P>0.05).However,the CST injury scores had significantly positive correlation with the NIHSS score before examine and 30 days,90 days after the onset of ADL scores(r=0.537,0.716,0.777,respectively,P<0.05).Conclusion:1).The variations of FA and ADC value in different phases of cerebral infarction have some regularities,they can reflect the pathophysiological changes of cerebral ischemic strokes.2).The rFA,rADC value of infarction lesions cannot predict patients’ clinical prognosis and motor function damage,need to consider the influence of infarction lesions’ volume and location.3).The CST injury scores can be used early as a objective indicator for evaluating the motor function injury and clinical prognosis.Part Ⅱ The preliminary research of MR diffusion tensor imaging in Wallerian Degeneration of corticospinal tract after cerebral ischemic strokeObjective:To explore the evolution of MR diffusion tensor parameters in Wallerian degeneration of ipsilateral corticospinal tract after cerebral ischemic stroke and investigate the relationship between fractional anisotropy by using DTI in the CST and limb motor deficit in patients.Methods:All twenty patients met the inclusion criteria with cerebral infarction were underwent repeatedly regular head MRI scans and whole brain DTI data acquisition at time of within 14 days,30 days and 90 days after infarction onset.Quantitative ADC and FA values were measured on region of interest(ROI)at the bilateral frontal posterior limb of internal capsule(FPLIC)and base of cerebral peduncle(BCP).The ratios of fractional anisotropy(rFA)and apparent diffusion coefficient(rADC)were calculated between the affected and unaffected CSTs.The neurological examinations including NIHSS and ADL were performed in all cases before the first scan and 30 days,90days after cerebral infarction and the relationship between rFA of ROI in the CST and neurological scores in patients were analyzed respectively in different time point.Results:1.The FA values of affected CST began to decrease at the average 5 days or so from attack.The average FA value of BCP in affected CST compared with the unaffected side in the first scan and 30 days,90days after cerebral infarction have reduced 9.90%,23.7%,20.7%,respectively.And the average FA value of FPLIC in affected CST have reduced 9.40%,4.9%,19.6%,respectively.2.The FA values of FPLIC in affected CST was reduced slowly with the extension of time,however,the FA values of BCP in affected CST was decreased obviously within the first 30 days,increased slowly from 30 days to 90 days after infarction onset and remained relatively stable.The FA values of ROIs in affected CST were significantly lower than the unaffected side always(P<0.05).But,the ADC values of ROIs in affected CST were no significantly higher than the unaffected side all the time(P>0.05).3.The rFA of ROIs in CST were significantly correlated with motor deficit only at 30 days after infarction onset(r=-0.500,-0.668,respectively,P<0.05).Conclusion:1).DTI could detect Wallerian degeneration of corticospinal tract as early as the average 5 days or so after infarction attack,it is a sensitive way of monitoring the change in cerebral white matter microstructure.2).DTI quantitative parameters ADC and FA value can reflect the dynamic pathological changes of Wallerian degeneration in corticospinal tract,such as the disintegration of axons and demylination were a highly mechanical evolution process.3).The rFA value of Wallerian degeneration in corticospinal tract will contribute to evaluating the condition of motor function recovery,this study highlights the utility of imaging follow-up at 30 days and the potential of DTI as a surrogate marker in clinical trials.