Value Of One-stop Multimodality CT In AIS With Unilateral MCA Stenosis

Objective:To investigate the diagnostic value of one-stop multimodality CT in acute ischemic stroke(AIS),and to find the relationship between the degree of unilateral middle cerebral artery(MCA)stenosis and cerebral CT perfusion imaging(CTPI)perfusion parameters.Materials and Methods:One-stop multimodality CT was performed in 158 patients with clinically diagnosed AIS,including non-enhanced CT of the head,CTA of the head and neck,and CTPI of the head.The CT data were stored in DICOM format,and image analysis and post-processing were performed on a GE ADW 4.7 workstation.Non-enhanced CT of the head excluded intracranial hemorrhage and space-occupying lesions and observed signs of early cerebral infarction.The original images of head and neck CTA were obtained by subtraction technique.The location of vascular stenosis was observed and the degree of vascular stenosis was measured by MPR,VR and MIP.The grade of MCA stenosis was classified according to WASID standard.The original images of head CTPI were post-processed using perfusion software to generate pseudocolor maps of five perfusion parameters such as CBF,CBV,MTT,TTP,and PS,and the perfusion parameter values of the brain tissue on the rear and mirror sides were measured and recorded,respectively.SPSS 21.0 statistical software was used for data processing.Paired t test was used for comparison of perfusion parameters in groups.One-way analysis of variance was used for comparison of perfusion parameters between groups.For pairwise comparisons,the LSD method was used for equal variances,and the Games-Howell test was used for unequal variances.Fisher’s exact test was used to compare the difference between the degree of vascular stenosis and perfusion stage when enumeration data were compared.Spearman correlation analysis was used to analyze the correlation between the degree of MCA stenosis and perfusion stage and perfusion parameters.Results:1.Of the 158 patients,13 patients were found to have early signs of cerebralinfarction on unenhanced CT,including insular band sign in 2 patients,lenticularblurred sign in 1 patient,gyral swelling and sulcus narrowing in 7 patients,and middle cerebral artery dense artery sign in 3 patients.2.Of the 158 patients,152(96.20%)patients were found to have vascular stenosis or occlusion by CTA,32(21.05%)patients had unilateral carotid artery(including common carotid artery and internal carotid artery)stenosis,58(38.16%)patients had unilateral MCA stenosis,and 62(40.79%)patients had multisegmental and multiple vascular stenosis.There were 58 patients of unilateral MCA stenosis,32 patients of left MCA stenosis,26 patients of right MCA stenosis,42 patients of Ml stenosis and 16 patients of M2 stenosis.According to the degree of unilateral MCA stenosis,there were 19 patients of mild stenosis group,16 patients of moderate stenosis group and 23 cases of severe stenosis/occlusion group.3.Of the 158 patients,115 patients were found to have abnormal perfusion by CTPI.Of the 58 patients with unilateral MCA stenosis,39 had abnormal CTPI,including 6(31.58%)patients in the mild stenosis group,12(75.00%)patients in the moderate stenosis group,and 21(91.30%)patients in the severe stenosis/occlusion group.The CTPI perfusion stages of the 39 patients were as follows:stage Ⅰ i in 4 patients,stage Ⅰ 2 in 10 patients,stage Ⅱ1 in 12 patients,and stage Ⅱ2 in 13 patients;including stage Ⅰ 1 in 3 patients,stage Ⅰ 2 in 2 patients,and stage Ⅱ1 in 1 patient in the mild stenosis group;stage Ⅰ 1 in 1 patient,stage Ⅰ 2 in 4 patients,stage Ⅱ1 in 5 patients,and stage Ⅱ2 in 2 patients in the moderate stenosis group;and stage Ⅰ 2 in 4 patients,stage Ⅱ1 in 6 patients,and stage Ⅱ 2 in 11 patients in the severe stenosis/occlusion group.4.Relationship between the degree of unilateral MCA stenosis and CTPI perfusion stage:There was significant difference in the perfusion stage among the three stenoses(P=0.009).Spearman correlation analysis showed that the degree of unilateral MCA stenosis was positively correlated with CTPI stage(r=0.557,P=0.000),that is,the more severe the MCA stenosis,the more severe the perfusion injury.5.Comparison of perfusion parameters among the three stenosis groups:Compared with the mirror side brain tissue,TTP was prolonged in the mild stenosis group(P<0.05);CBF was decreased,TTP and MTT were prolonged in the moderate stenosis group(P<0.05);CBF and CBV were decreased,TTP and MTT were prolonged in the severe stenosis/occlusion group(P<0.05);there were significant differences in rCBF values and rMTT values among the three stenosis groups(P<0.05),but there was no significant difference in rCBV values and rTTP values(P>0.05).6.The relationship between the degree of unilateral MCA stenosis and CTPI perfusion parameters:the degree of unilateral MCA stenosis was positively correlated with rTTP and rMTT(r=0.458,P=0.003;r=0.765,P=0.000,respectively)and negatively correlated with rCBF(r=-0.600,P=0.000),and there was no significant correlation between the degree of stenosis and rCBV.7.Changes of vascular surface permeability(PS)in the early stage of cerebral infarction:There was no significant difference in the absolute value of PS in the group of patients with stage I(P>0.05),there was significant difference in the absolute value of PS in the group of patients with stage Ⅱ(P<0.01),there was significant difference in the relative value of PS between patients with stage Ⅰ and Ⅱ(P<0.05),and there was no significant difference in the relative value of PS between patients with stage I 1 and Ⅰ 2,Ⅱ1 and Ⅱ2(P>0.05).Conclusions:1.One-stop multimodality CT can simultaneously show the brain structure,responsible vessels and the degree of stenosis,as well as the changes of hemodynamic perfusion parameters of brain tissue,providing multidimensional information for the early diagnosis of AIS.2.The positive rate of CTPI in the unilateral MCA moderate and severe stenosis/occlusion groups was higher than that in the mild stenosis group;the degree of unilateral MCA stenosis was moderately positively correlated with the CTPI stage,indicating that the more severe the degree of MCA stenosis,the more severe the degree of perfusion injury.3.The more severe the degree of unilateral MCA stenosis,the greater the TTP and MTT values,and the smaller the CBF;there was no significant correlation between the degree of stenosis and CBV.4.Changes of vascular surface permeability(PS)in the early stage of cerebral infarction:In the early stage of cerebral infarction,especially in stage II,there has been a change of increased vascular surface permeability,suggesting that the blood-brain barrier is slightly damaged.