Application Of Vessel Wall Imaging Technology In Exploring The Etiology Of Stroke And Characteristic For Plaque

Objective:In this study,High-resolution magnetic resonance vascular wall imaging(VWI)was used to identify the etiology of acute ischemic stroke(AIS)caused by intracranial large vessel occlusion at 4.5-24 hours of onset,and to explore the risk factors associated with intracranial atherosclerotic plaque.Methods:This review retrospectively collected patients with intracranial large vessel occlusion with intracranial macrovascular occlusion who had a duration of illness of 4.5to 24 hours from August 1,2019 to August 1,2022,were assessed by MR(including DWI,3D TOF-MRA,T2-FLAIR,VWI sequences)and treated with vascular recanalization.The optimized MR scanning process is: firstly,scanning the DWI sequence(scanning time<1min)to identify the infarct core;Secondly,the 3D TOF-MRA sequence(scanning time<3min)is scanned to identify the responsible blood vessels;After the above two serial scans,clinicians can basically determine whether vascular recanalization is required,and if it is still necessary to refer to the vascular collateral circulation,scan the T2 FLAIR sequence(scan time<2min);Finally,the VWI sequence(scanning time<5min)is scanned,only the anterior or posterior circulation where the responsible blood vessel is located,and at the same time as the sequence is scanned,the clinician explains the condition to the patient or his/her family,obtains informed consent for surgery,confirms the indications for surgery,notifies and confirms the operating room,surgeon and preoperative preparation.Ensure that the total scanning time does not exceed 20 minutes or do not extend the time from admission to thrombolytic therapy(DNT)for acute stroke patients,and terminate the scan immediately if the patient does not cooperate.A total of 3 chief physicians from the Department of Imaging,Neurointerventional Surgery and Neurology,who have been practicing for more than 20 years,discussed the etiology of the AIS patient according to the proposed gold standard,and reached a consensus as the final diagnosis result of the patient.The proposed gold standard is vascular recanalization combined with clinical comprehensive evaluation,which is defined as a comprehensive evaluation based on clinical history,laboratory tests,imaging findings(except VWI),preoperative cerebral angiography,intraoperative procedure,postoperative removal of contents,and postoperative cerebral angiography results.Two radiologists who have been engaged in radiology for more than 10 years and do not know the clinical information of the patient are used to determine the etiology only based on the MRI images(mainly VWI)of AIS patients after unified training,and if the diagnosis results are inconsistent,the two will reach a consensus through negotiation.The diagnostic criteria for VWI are as follows: thrombus:(1)compared with the contralateral or adjacent normal tube wall,the blood vessel wall at the lesion is not significantly thickened;(2)The lesion is discontinuous with the intima of the blood vessel wall;(3)The lesion signal is higher than the blood vessel wall;(4)The lesion signal is uniform.Atherosclerotic plaque:(1)Compared with the contralateral or adjacent normal tube wall,the blood vessel wall at the lesion is eccentric thickening;(2)The lesion is continuous with the inner membrane of the blood vessel wall;(3)lesion signals are equal or slightly higher than vascular wall signals;(4)The lesion signal is uneven;(5)The lesion is more limited(range< 1/3 of the vascular segment).Dissection:(1)"Inner membrane flap" : the arc between the linear isosignal shadow passing through the empty cavity or the arc between the empty cavity and the hyper-signal intramural hematoma;(2)"Double chamber sign" : the flowing blood vessel is divided into double chambers by the inner membrane flap;(3)Intramural hematoma: crescent-shaped or high signal appears on the tube wall.Results:A total of 28 patients were collected in this study,and the patients were divided into thromboembolism group(20 cases),atherosclerotic plaque group(6 cases)and dissection group(2 cases)according to the proposed gold standard,with an average age of(65.0±2.25)years,including 18 males,accounting for 64.3%,and 10 females,accounting for 35.7%.The two radiologists distinguished the etiology based on MRI images(mainly VWI)alone,and the imaging diagnosis results were well agreed(Kappa= 0.745).Since the VWI manifestations of the two patients with dissection in this study were typical,the accuracy,sensitivity,specificity,positive predictive value and negative predictive value of VWI for the diagnosis of the dissection group were 100%.The dissection group was not included in the follow-up study because its characteristic VWI imaging findings were clearly distinguishable from the other two groups.Accuracy of VWI in the diagnosis of thromboembolism and atherosclerotic plaques was 88.5%,sensitivity was 95%,specificity was 66.7%,positive predictive value and negative predictive value were 90.5% and 80%,respectively.Univariate analysis of VWI manifestations in patients in thromboembolism group and atherosclerotic plaque group showed that eccentric thickening of tube wall was more common in atheroembolic plaque group than in thromboembolism group(83.3%vs.18.5%,P<0.05).The signal was more uniform in the thromboembolism group(77.8% vs.16.7%,P<0.05);The atheroplaque group had a greater remodeling index than the thromboembolism group(1.04±0.31 vs.0.65±0.26,P<0.05).After multivariate analysis,it was found that the reconstruction index was the only characteristic manifestation(OR=1.122,95%CI: 1.002～1.256,P<0.05).Conclusion:High-resolution magnetic resonance vascular wall imaging can help identify the etiology of AIS patients due to intracranial large vessel occlusion,thereby guiding the evaluation of AIS patients before vascular recanalization.T This study also found that a large remodeling index is a characteristic VWI manifestation of intracranial atherosclerotic plaques.