| Objective:To investigate the clinical significance of different TI ASL scans in acute ischemic stroke patients with high perfusion in infarction area and around the infarction area,and to explore the correlation between high perfusion display and hemorrhagic transformation,clinical symptom and prognosis.We contrast clinical data and image data such as ASL of DWI positive acute ischemic stroke patients with DWI negative patients,to investigate the diagnostic value of ASL in DWI negative acute ischemic stroke,to strengthen the understanding of DWI negative acute ischemic stroke,and to perform vascular reperfusion therapy in time.Materials and methods: Eighty-seven patients with acute cerebral ischemic stroke of unilateral cerebral hemisphere were included.T1 WI,T2WI,DWI,FLAIR,MRA,SWI and ASL were scanned by Siemens 3.0T MRI.Depending on whether abnormal high signal infarct can be visually observed on DWI images,all patients were divided into two groups: DWI positive group(abnormal hyperintense infarction was observed on DWI images)and DWI negative group(abnormal hyperintense infarction was not observed).Statistical software SPSS 23.0 was used to analyze the difference of baseline clinical data,NIHSS score on the day of admission,mRS score on the 90 th day after discharge and incidence of perfusion abnormalities between the two groups.We also analyzed the correlation between whether DWI showed the infarct and the severity of the responsible artery stenosis and levels of SWI venous abnormality.(1)High perfusion was defined as rCBF>120% in the affected side versus the healthy side.(2)Normal perfusion was defined as 80%<rCBF?120% in the contralateral side.(3)Low perfusion was defined as rCBF?80% in the contralateral side.According to two ASL images with TI of 1500 ms and 2500 ms respectively,all patients were divided into three groups:(1)non-high perfusion group: both ASL-CBF images showed low perfusion or normal perfusion;(2)delayed high perfusion group: the ASL-CBF iamges of TI = 1500 ms showed low perfusion or normal perfusion while the ASL-CBF iamges of TI = 2500 ms showed high perfusion;(3)high perfusion group: both ASL-CBF iamges showed high perfusion.Statistical software SPSS 23.0was used to analyze whether the baseline clinical data,NIHSS score on the day of admission,infarct volume,incidence of intracranial hemorrhage and mRS score on the 90 th day after discharge had statistical significance.And we analyzed thecorrelation among the perfusion of three groups and the severity of the responsible artery stenosis and levels of SWI venous abnormality.Result:(1)Eighty-seven patients with acute ischemic stroke were collected in this study.There were 78 cases in DWI positive group and 9 cases in DWI negative group.Among 78 cases of DWI positive group,33 cases were single infarction and45 cases were multiple infarction;ASL images showed 15 patients with high perfusion,including 5 patients with high perfusion in infarction area and around infarction,4 patients with high perfusion in infarction area and 6 patients with high perfusion around infarction area.Among the 9 patients in DWI negative group,8patients had low perfusion regions in the cerebral hemisphere which was consistent with clinical symptoms,and 1 patient had no perfusion abnormalities.(2)Among the 78 DWI positive patients,63 cases were in non-high perfusion group,6 cases were in delayed high perfusion group and 9 cases were in high perfusion group.There was no significant difference in baseline clinical data(age,gender,diabetes,hypertension grade,atrial fibrillation,coronary heart disease and smoking)and infarct volume in the three groups(P>0.05).NIHSS score on admission day of non-high perfusion group was significantly higher than that of high perfusion group and the difference between the two groups was statistically significant(P=0.043).The mRS score on the 90 th day after discharge of non-high perfusion group was significantly higher than that of high perfusion group and the difference between the two groups was statistically significant(P=0.048).There was significant difference in the incidence of hemorrhagic transformation among the three groups(P=0.044).There was no statistical difference between any two groups,but the incidence of intracranial hemorrhage in high perfusion group was significantly higher than that in non-high perfusion group(P=0.022)and that in delayed perfusion group(P=0.287).The degree of responsible artery stenosis in non-high perfusion group was more serious than that in other two groups and the correlation between the degree of responsible artery stenosis and high perfusion in three groups was statistically significant(P=0.014).SWI showed that the severity of venous abnormalities in non-high perfusion group was significantly higher than that in the other two groups and the correlation between high perfusion and venous abnormalities in the three groups was statistically significant(P=0.000).(3)The incidence of abnormal perfusion in DWI positive group and DWInegative group was not statistically significant(P>0.05).While the positive rate of DWI examination on acute ischemic stroke was 89.7%(78/87),the positive rate of DWI combined with ASL was close to 100%(86/87).(4)Baseline clinical data(age,gender,diabetes,hypertension grade,atrial fibrillation,coronary heart disease,and smoking)in DWI positive group and DWI negative group were not statistically significant(P>0.05).In the DWI-negative group,NIHSS scores on the day of admission were significantly lower than those in the DWI-positive group.There was a statistically significant difference between the two groups(P=0.026).In the DWI-negative group,the mRS score on the 90 th day after discharge was significantly lower than that in the DWI-positive group.There was a statistically significant difference between the two groups(P=0.044).The severity of stenosis of the responsible arteries in the DWI-negative group was lower than that in the DWI-positive group.The correlation between whether DWI showed the infarct and the severity of the responsible artery stenosis was statistically significant(P=0.041).The SWI showed significantly higher levels of venous abnormalities in the DWI-positive group than in the DWI-negative group.The correlation between whether DWI showed the infarct and the level of venous abnormalities was statistically significant(P=0.002).Conclusion:(1)The patients whose TI=1500 ms and 2500 ms ASL images both showed high perfusion had better symptom severity and clinical prognosis than patients without high perfusion.Patients in the high perfusion group were more likely to have hemorrhagic transformation.(2)There was a significant correlation between high perfusion in ASL images and the degree of responsible artery stenosis.The degree of vascular stenosis in high perfusion group was better than that in delayed perfusion group.The possible reason was that high perfusion was related to vascular recanalization and destruction of blood-brain barrier,while delayed high perfusion was related to slow blood flow and collateral circulation formation of stenotic vessels.(3)As a non-invasive and reproducible technique for assessing blood perfusion,ASL can compensate for the lack of DWI,improve the accuracy of diagnosis of acuteischemic stroke,and guide clinical treatment to a large extent.(4)Patients with DWI-negative acute ischemic stroke have milder clinical onset symptoms,better clinical prognosis,and less severe vascular responsibility than DWI-positive patients. |
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