Application Study Of Magnetic Resonance DWI DTI And SWI In Thrombolytic Diagnosis And Treatment Of New Cerebral Infarction

Objective:To explore the application value of diffusion weighted magnetic resonance imaging(DWI),diffusion tensor imaging(DTI)and susceptibility weighted imaging(SWI)in the early diagnosis of cerebral infarction and intravenous thrombolysis therapy.and to verify the correlation between hemorrhage transformation(HT)and microhemorrhage(CMBs)in intravenous thrombolysis of cerebral infarction.Methods:This study collected 138 inpatients who visited the emergency green channel of our hospital from November 2016 to September 2018 and were clinically diagnosed with new cerebral infarction.The patients were between 30 and 80 years old,the average age of the patients was 64.29±1.53 years,including 76 males and 62females.All patients were scanned with routine MRI sequence and diffusion weighted imaging(DWI).The DWI series showed high signal in the lesion area(b=0,1000s/mm2),and the ADC value in the corresponding area decreased,suggesting the patient hed new cerebral infarction.SWI and DTI sqences were added,the lesions were observed and compared in different squences imaging.Apparent diffusion coefficients(ADC),mean diffusivity(MD)and fractional anisotropy(FA)values of cerebral infarction lesions and the symmetrical positions in normal hemispheres were measured and compared.The correlations between relative MD(rMD)value,relative FA(rFA)value and disease time were analyzed.Diffusion tensor imaging(DTI)evaluated the injury degree of white matter nerve fiber bundle in cerebral infarction area,and to clarify the ischemic penumbra of cerebral infarction;Susceptibility weighted imaging(SWI)sequence was used to detec whether the infarct was accompainied cerebral microbleeds(CMBs).Then whether there was cerebral microbleeds(CMBs)in the infarcted focus according to SWI was used as a grouping standard.The 56 cases that met the requirements for intravenous thrombolysis were divided into 21 cases in CMBs group and 35 cases in without CMBs group,all of which were treated with rapid intravenous thrombolysis,MRI SWI sequences was reexamined within 24 hours to detect the number of cases with hemorrhagic transformation(HT),and to compare whether there was a statistical difference between the CMBs group and the CMBs group without CMBs.Results:The disply rate on DWI in showing ultra-acute and acute cerebral infarction lesions was 100%,which was superior to other sequences of conventional MRI,obiously(P<0.05).compared with healthy side,MD values of infarction lesions were lower at ultra-acute phase(P<0.05).but at sub-acute phase,there wes no statistically difference between the affected and nomal sides(P>0.05).FA values was no consistent changes at ultra-acute phase(P>0.05),but at the later separate phases,FA values reduced successively(P<0.05).The rMD value of infarction lesions was positive correlated with disease time(r_s=0.987,P<0.05);The rFA value of infarction lesion was negative correlated with disease time(r_s=-0.993,P<0.05).No obvious hemorrhage was observed in conventional MRI and CT before thrombolytic therapy in CMBs group,while SWI showed hemorrhagic infarction.After intravenous thrombolysis treatment with a total of 13 cases with blood volume increases,namely in HT,9 cases into substantial hematoma type I,4 cases were converted into substantial hematomaⅡtype,there was an obvious mass effect,8 cases after thrombolysis was not obviously changed;CT and SWI scan did not find CMBS before thrombolytic therapy in the non-CMBs group.After intravenous thrombolysis,SWI found that CMBs appeared in the lesion in 5 cases,ECASS was classified as hemorrhagic infarction type I,and CMBs was not seen in 30 cases.Statistical analysis showed that the number of HT cases in CMBs group was more than that in the non-CMBs group,and there was a statistical difference between the two groups(X2=12.19,P<0.05).Conclusion:DWI SWI and DTI could quickly evaluate the hemodynamic state of ischemic brain tissue in vivo without trauma,providing a simple and feasible new method to study the blood perfusion of ischemic brain tissue.DWI is susceptive in showing new cerebral infarction,DTI could accurately evaluate the damage of cerebral cortex and spinal tract in ischemic brain tissue and define ischemic penumbra.SWI could clearly and sensitively detect the microbleeds in cerebral ischemia,reflect the degree of reperfusion injury,observe the hemorrhage transformation(HT)during intravenous thrombolysis treatment,and provide imaging basis for early selection of reasonable treatment schemes in clinical practice.