| Background and objective:The severe stenosis or occlusion of the middle cerebral artery will lead to the obstruction of local blood circulation in the brain,which can cause ischemic necrosis of the brain tissue in the blood supply area.In the case of cerebral ischemia,collateral circulation plays an important role in maintaining cerebral perfusion,metabolism and cellular function.The aim of this study was to compare the difference of perfusion and collateral circulation compensation between symptomatic and asymptomatic patients with severe stenosis or occlusion of unilateral middle cerebral artery by using 3D pseudo-continuous arterial spin labeling(3D PCASL)of two PLDs and territorial arterial spin labeling(t-ASL)techniques.Materials and methods:49 patients with severe stenosis or occlusion of unilateral middle cerebral artery(MCA),admitted to our hospital From May 2020 to February 2021,were selected.MRA showed that the degree of unilateral middle cerebral artery stenosis was≥75%.According to whether the patients had symptoms related to the blood supply area of the diseased vessels in nearly half a month,they were divided into symptomatic group and asymptomatic group.Symptomatic group included patients with cerebral infarction and patients with transient ischemic attack(TIA).All patients were scanned by conventional brain MRI,DWI,MRA,3D PCASL(PLD1.5s,2.5s)and t-ASL.The cerebral blood flow(CBF)of the affected side and the mirror side of ASL PLD1.5s and PLD2.5s were measured.The differences of the ASL CBF values of the two PLD between the affected side and the healthy side were compared between the symptomatic group and the asymptomatic group.The bilateral internal carotid artery,vertebrobasilar artery and ipsilateral external carotid artery were labeled by t-ASL to analyzed the changes of the blood supply area of each artery.Combined with MRA,the situation of collateral compensation in the affected side of MCA blood supply area was compared between the two groups,and the sources of compensation were analyzed.Results:1.In the asymptomatic group,the CBF values in the MCA blood supply area of the affected side and the healthy side of ASL PLD 1.5s were 26.11±8.26 ml/(100g·min)and 48.66±8.92ml/(100g·min)respectively,and the difference was statistically significant(t=-31.87,P<0.001),The CBF values in the MCA blood supply area of the affected side and the healthy side of ASL PLD2.5s were 46.36± 11.20 ml/(100g·min)and 48.21 ±7.89ml/(100g ·min)respectively,and the difference was not statistically significant(t=-1.52,P>0.05).2.In the symptomatic group,the CBF values in the MCA blood supply area of the affected side and the healthy side of ASL PLD1.5s were 17.22±4.64 ml/(100g·min)and 40.60±8.59 ml/(100g·min)respectively,and the difference was statistically significant(t=-13.47,P<0.001).The CBF values in the MCA blood supply area of the affected side and the healthy side of ASL PLD2.5s were 30.02±6.66ml/(100g·min)and 43.36±6.55ml/(100g·min)respectively,and the difference was statistically significant(t=-11.39,P<0.001).3.Compared with the asymptomatic group,the CBF values in the MCA blood supply area in the affected and healthy sides of ASL PLD1.5s and PLD2.5s in the symptomatic group were significantly lower,and the differences were statistically significant(all P<0.05).4.On the affected side,the increase of ASL PLD from 1.5s to 2.5s MCA CBF in asymptomatic group was more than that in symptomatic group,and the difference was statistically significant(t=-5.64,P<0.001).The increase of ASL PLD from 1.5s to 2.5s MCA CBF in the affected side was significantly higher than that in the healthy side,and the difference was statistically significant(t=13.66,P<0.001).5.Compared with the asymptomatic group,the collateral compensation of the affected MCA blood supply area on t-ASL in the symptomatic group was poor,and the difference was statistically significant(x2=6.979,P<0.05),At the same time,there were more patients with secondary collateral compensation in the asymptomatic group than in the symptomatic group,and the difference was statistically significant(x2=4.53 8,P<0.05).6.In some patients with collateral compensation,t-ASL showed that most of the compensations in the MCA supply area were from the vertebrae-basilar artery,some were from the contralateral internal carotid artery,and a few were from the ipsilateral external carotid artery.Conclusion:Compared with symptomatic patients,asymptomatic patients had stronger collateral perfusion on 3D PCASL of 2 PLDs,and the number of patients with secondary collateral compensatory opening was larger.Combined application of two PLDs ASL and t-ASL can provide a more comprehensive assessment of collateral compensation after unilateral middle cerebral artery severe stenosis or occlusion. |
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