Clinical Research Of Multimodal Imaging In Thrombotomy For Acute Ischemic Stroke

Stroke is still one of the most lethal and disabled diseases in the world.More than 40% of ischemic stroke is caused by acute occlusion of large vessels,which increases the mortality of patients by 3.5 times in 6 months and decreases the proportion of good prognosis by 67%.In 1995,the NINDS study published in the New England Journal of Medicine established the role of intravenous thrombolysis in the treatment of acute cerebral infarction.Unfortunately,this effective treatment can only be given in a few hours,so what about a large number of patients who exceed the thrombolytic time window? With the historical development of endovascular therapy for acute ischemic stroke and the deepening of research in the field of reperfusion,the time window of reperfusion therapy has been broadened from 3 hours to 3-4.5 hours and then to 6 hours.In2018,two large-scale studies,DAWN and DEFUSE-3,further extended the time window for thrombectomy from 6 hours to 24 hours.Compared with the drug treatment group,the proportion of reperfusion and recanalization in thrombectomy group was higher.As far as safety is concerned,there is no significant difference in the incidence of symptomatic intracranialhemorrhage between thrombectomy group and drug treatment group,and the mortality rate tends to decrease.The purpose of reperfusion therapy is to restore the blood flow of brain tissue as soon as possible and save the ischemic penumbra tissue(brain tissue that has lost its physiological function but has not died).However,the CT examination of the head immediately after the thrombectomy often appears the postinterventional cerebral hyperdensities(PCHDs)caused by ischemia-reperfusion injury of blood-brain barrier.The comparison of the nature,risk factors and impact of the PCHDs on prognosis need to be further studied.Furthermore,endovascular treatment after multi-modal imaging screening in patients who receiving large doses of contrast agent in a short time,which will cause contrast agent kidney damage and the impact on the prognosis of acute ischemic stroke,remains to be explored.PART ONE CLINICAL RESEARCH OF PCHDS AFTER THROMBECTOMY FOR ACUTE ISCHEMIC STROKEObjective: To study the nature of PCHDs in brain tissue after thrombectomy for acute ischemic stroke after multi-modal imaging screening,and whether NCCT scan can differentiate contrast medium extravasation from hemorrhage plus contrast medium extravasation.The specificity and sensitivity of diffussion weighted Imaging(DWI)sequence of MRI in differentiating hemorrhagic transformation after thrombectomy.Methods: We conducted a retrospective analysis in patients with acute ischemic stroke in our hospital from March 2014 to July 2017 after thrombectomy and multimodal imaging screening.According to whether there is PCHDs in brain tissue on NCCT after thrombectomy,the patients were divided into PCHDs group and non-PCHDs group.Patients with PCHDs were selected for further analysis.The definition of PCHDs was that the CT value increased by 5 HU compared with the mirror area of contralateral brain tissue.The low signal of susceptibility weighted imaging(SWI)sequence in MRI was diagnosed as hemorrhage.The low signal intensity of DWI sequence in the diffusion-limited area was defined as hemorrhage.The sensitivity and specificity of DWI sequence in differentiating PCHDs after thrombectomy were observed by comparing with SWI sequence.Results: A total of 121 patients were included in the analysis.All patients had complete multimodal imaging examination(including NCCT,cranio-cervical CTA,head CTP)before thrombectomy,and had mismatch between core infarction and ischemic penumbra.Ninety-four patients had PCHDs(77.7%)on plain CT scan after operation,of which 71 patients had hemorrhagic transformation confirmed by SWI.The sensitivity,specificity,positive predictive value and negative predictive value were 16.9%,69.6%,63.0% and 21.0% respectively,and the area under the curve was 0.432.Reperfusion hemorrhagic transformation was diagnosed by the method of CT value greater than 90 HU,and the sensitivity,specificity,positive predictive value and negative predictive value of CT density > 90 HU for predicting hemorrhagic transformation after thrombectomy were 14.1%,9.1%,respectively.1.3%,83.0% and 26.0%,the area under the curve is0.527.The sensitivity,specificity,positive predictive value and negative predictive value of low signal in high signal area of DWI sequence in predicting hemorrhagic transformation after thrombectomy were 95.8%,95.7%,99.0% and 88.0% respectively,and the area under curve was 0.957.Conclusion: The incidence of PCHDs on NCCT is high after thrombectomy.NCCT scan can not distinguish extravasation from reperfusion hemorrhage.The sensitivity and specificity of CT value lower than 50 HU or higher than 90 HU to exclude or diagnose reperfusion hemorrhage are reduced.Low signal intensity in the diffusion-limited areaof DWI sequence can be used to differentiate extravasation from hemorrhage plus contrast medium extravasation.after reperfusion therapy.PART TWO CORRELATION ANALYSIS OF PCHDS ANDPROGNOSIS AFTER THROMBOLYTIC THERAPY FOR ACUTE ISCHEMIC STROKE GUIDED BY MULTI-MODE IMAGINGObjective: The incidence of PCHDs on NCCT scan after thrombectomy for acute ischemic stroke is high,which reflects the destruction of blood-brain barrier after reperfusion.The purpose of this study was to explore: 1)Risk factors of reperfusion injury after thrombectomy for acute ischemic stroke;2)The effect of reperfusion injury on prognosis after thrombectomy for acute ischemic stroke.Methods: We conducted a retrospective analysis in patients with acute ischemic stroke in our hospital from March 2014 to July 2017 after multimodal imaging screening and thrombectomy.According to whether there is PCHDs on NCCT after operation,the patients were divided into PCHDs group and non-PCHDs group.Results: There were 140 patients with acute cerebral ischemic stroke in this study.The patients were divided into PCHDs group(n=108,77.1%)and non-PCHDs group(n=32,22.9%).In the PCHDs group,the PCHDs group with CT was more likely to have final hemorrhagic transformation(79(73.1)vs.3(9.4),P< 0.001).According to the dichotomization of m RS≥ 3 and m RS < 3,the prognosis of patients was divided into two groups:poor outcome and favorable outcome.In the poor outcome group,the patients were older(P= 0.048),had higher baseline NIHSS score(P<0.001),more poor reperfusion rate(P= 0.001)and final hemorrhagic transformation(P= 0.011).In multinomial Logistic regression analysis,NIHSS score(P< 0.001),puncture to perfusion time(P< 0.001),poor reperfusion(P= 0.010)and final hemorrhage transformation(P= 0.049)could independently predict the 90-day poor outcome in patients after thrombectomy.The area under the curve of NIHSS score,puncture to perfusion time,poor reperfusion and final hemorrhagic transformation in predicting poor outcome were 0.742,0.716,0.597 and 0.614,respectively.Conclusion: PCHDs on NCCT scan after thrombectomy reflect the destruction of blood brain barrier.The risk factors are correlated to ischemia reperfusion time and baseline NIHSS score,which will affect the prognosis of patients,reduce short-term neurological improvement and increase the risk of hemorrhage transformation.In this study,endovascular thrombectomy was performed after multimodal imaging screening.Older age,higher baseline NIHSS score,hemorrhagic transformation after reperfusion,and longer operation duration may be risk factors for poor prognosis.PART THREE STUDY ON CONTRAST AGENT RENAL INJURY GUIDED BY MULTIMODAL IMAGING IN ENDOVASCULAR THERAPYObjective: Multimodal CT has been widely used in the screening of patients with acute ischemic stroke in order to screen patients with ischemic penumbra for intravascular thrombectomy.A large amount of contrast medium intake in a short time may cause contrast medium kidney damage.In this study,we retrospectively analyzed and discussed the contrast medium renal injury treated by endovascular thrombectomy after multimodal CT examination.Methods: A retrospective analysis was made on the patients with acute ischemic stroke who were hospitalized in our hospital from March 2014 to May 2017 after multimodal imaging screening.Venous blood was collected before multimodal CT examination and renal function was reexamined at24 hours to 72 hours after operation.The levels of creatinine and the incidence of acute kidney injury were compared before and after taking contrast medium.Results: A total of 252 patients with acute ischemic stroke were enrolled,184 of them received intravascular therapy after multimode CT examination and 68 received intravenous thrombolysis after multimode CT examination.There were no significant differences in creatinine mean,24-hour urine volume,incidence of acute kidney injury,dialysis and mortality between the two groups at 24 hours to 72 hours.Univariate regression analysis showed that diabetes mellitus,duration of operation and times of thrombectomy may be related to contrast medium renal injury.Multivariate regression analysis showed that only diabetes mellitus was a risk factor for contrast medium renal injury.Conclusion: Multimodal CT evaluation of acute ischemic stroke after intravascular thrombolysis treatment,patients in a short period of time to take large doses of contrast agent,but the incidence of contrast agent renal injury and multi-modal CT evaluation of patients with simple intravenous thrombolysis has no significant difference.In patients with diabetes mellitus,intravascular thrombectomy after multimode CT increases the risk of contrast medium renal injury.