Application Value Of Prominent Vessel Sign On Susceptibility-weighted Imaging In Patients With Acute Ischemic Stroke

Part I Factors associated with prominent vessel sign on susceptibility-weighted imaging in acute ischemic strokeObjective:In patients with acute ischemic stroke,the oxygen extraction fraction is increased in the hypoperfused parenchyma,resulting in an increase in deoxyhemoglobin in veins and capillaries.Since deoxyhemoglobin is a paramagnetic substance with high magnetic susceptibility,asymmetric multiple hypointense vessels appear on susceptibility-weighted imaging(SWI),which is called prominent vessel sign(PVS).However,PVS is not displayed in all patients with acute ischemic stroke.A meta-analysis showed that the presence of PVS ranged from 34%to 100%.The factors related to the presence of PVS are still unclear at present.The purpose of our study was to investigate the factors affecting the presence of PVS in stroke patients.Methods:This was a prospective study conducted in the PLA Rocket Force General Hospital between August 2013 and August 2017.Consecutive ischemic stroke patients admitted within 24 hours from symptom onset underwent emergency multimodal MRI at admission.A standardized case report form was established for clinical data collection and data management.All images generated were saved on compact disk-read only memory.All patients were divided into PVS-positive group and PVS-negative group based on the presence or absence of PVS.Associated factors for the presence of PVS were analyzed using univariate analyses and multivariable Logistic regression analyses.Results:A total of 218 consecutive patients were enrolled.The patients consisted of 129(59.2%)men and 89(40.8%)women.The mean age was 66 ± 14 years.The median onset-to-MRI time was 3.4(interquartile range[IQR],2.6-4.5)hours.The occurrence rate of PVS was 55.5%(121/218)for all patients,while it was up to 100%(90/90)for anterior circulation stroke patients with large vessel occlusion.Univariate analyses showed significant differences between PVS-positive group and PVS-negative group in age,history of coronary heart disease,baseline NIHSS scores,total cholesterol,hemoglobin,anterior circulation infarct,large vessel occlusion,and cardioembolism.Multivariable Logistic regression analyses revealed that the independent factors associated with PVS were anterior circulation infarct(odds ratio[OR],13.7;95%confidence interval[CI],3.5-53.3),large vessel occlusion(OR,123.3;95%CI,33.7-451.5),and cardioembolism(OR,5.6;95%CI,2.1-15.3).Conclusions:Anterior circulation infarct,large vessel occlusion,and cardioembolism are independently associated with the presence of PVS.On SWI,PVS is almost always visible in patients with anterior circulation stroke due to large vessel occlusion.Part II Application value of prominent vessel sign on susceptibility-weighted imaging in patients with acute large vessel occlusion strokeObjective:In patients with acute ischemic stroke,the oxygen extraction fraction is increased in the hypoperfused parenchyma,resulting in an increase in deoxyhemoglobin in veins and capillaries.Since deoxyhemoglobin is a paramagnetic substance with high magnetic susceptibility,asymmetric multiple hypointense vessels appear on susceptibility-weighted imaging(SWI),which is called prominent vessel sign(PVS).However,the application value of PVS in patients with acute ischemic stroke,especially in patients with acute large vessel occlusion stroke,remains unclear.The purpose of this study was to analyze the effect of PVS on clinical outcome and to explore its application value in patients with anterior circulation stroke due to large vessel occlusion.Methods:This was a prospective study conducted in the PLA Rocket Force General Hospital between August 2013 and August 2017.Ischemic stroke patients admitted within 24 hours from symptom onset underwent emergency multimodal MRI at admission.The inspection sequences consisted of T1-weighted imaging(T1WI),T2-weighted imaging(T2WI),fluid-attenuated inversion recovery(FLAIR),magnetic resonance angiography(MRA),diffusion-weighted imaging(DWI)and SWI,etc.Patients with large vessel occlusion in the anterior circulation were enrolled consecutively.Follow-up MRI was performed within 24 hours after the recanalization therapy(including intravenous thrombolysis,endovascular treatment and bridging therapy).The clinical and imaging data of the patients were collected prospectively.The extent of PVS on SWI was assessed using the Alberta Stroke Program Early CT Score(ASPECTS)method and the SWI-DWI mismatch score was calculated.Recanalization status was evaluated on Follow-up MRA with Arterial Occlusive Lesion(AOL)recanalization score.Clinical outcome at 3 months after stroke was assessed by using the modified Rankin Scale(mRS)which was dichotomized into good(mRS 0-2)and poor outcome(mRS 3-6).Univariate analyses and multivariable Logistic regression models were used to analyze the relationship between PVS and clinical outcomes.Results:A total of 90 consecutive patients with acute anterior circulation stroke due to large vessel occlusion were enrolled.The prognosis was good in 51 cases(56.7%)and poor in 39 cases(43.3%).PVS was seen on SWI in all patients.Univariate analyses showed that patients in the good outcome group had higher SWI-DWI mismatch scores(P<0.001)and had a higher proportion of successful recanalization(P<0.001).There was no significant difference in SWI-ASPECTS between the two groups(P=0.798).In Logistic regression analyses,a multiplicative interaction between SWI-DWI mismatch score and recanalization status on clinical outcome was observed(P=0.037).The interaction term"SWI-DWI mismatch score × successful recanalization" was significantly associated with good outcome(odds ratio[OR],2,162;95%confidence interval[CI],1.046-4.468).Stratified analysis showed that the likelihood of good outcome increased with the increase of SWI-DWI mismatch score in the successful recanalization group(OR,2.140;95%CI,1.376-3.326),while there was no significant relationship between SWI-DWI mismatch score and clinical outcome in the unsuccessful recanalization group(OR,1.212;95%CI,0.933-1.574).Conclusions:The effects of SWI-DWI mismatch and recanalization status on clinical outcome were realized through their interaction.In anterior circulation stroke due to large vessel occlusion,patients with both high SWI-DWI mismatch scores and successful recanalization were more likely to achieve a good outcome,while patients with unsuccessful recanalization,or with successful recanalization but low SWI-DWI mismatch scores,were less likely to have a good prognosis.Part Ⅲ Relationship between prominent vessel sign on susceptibility-weighted imaging and leptomeningeal collateralizationObjective:In patients with acute ischemic stroke,the oxygen extraction fraction is increased in the hypoperfused parenchyma,resulting in an increase in deoxyhemoglobin in veins and capillaries.Since deoxyhemoglobin is a paramagnetic substance with high magnetic susceptibility,asymmetric multiple hypointense vessels appear on susceptibility-weighted imaging(SWI),which is called prominent vessel sign(PVS).Several studies have explored the relationship between PVS and collateral circulation,but the results are controversial.Some researchers found that extensive PVS was associated with poor leptomeningeal collateralization,while others argued that the more extensive the PVS,the better the collateral flow.Therefore,the relationship between PVS and collateral circulation needs to be further studied.Methods:We retrospectively enrolled patients with M1 segment occlusion of the middle cerebral artery who underwent emergency MRI and DSA within 24 hours from stroke onset.The extent of PVS on SWI was assessed using the Alberta Stroke Program Early CT Score(ASPECTS)method and the SWI-DWI mismatch score was calculated.Leptomeningeal collateralization on DSA images was assessed using the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology(ASITN/SIR)scale.The patients were divided into good collateral group and poor collateral group according to ASITN/SIR scores.The differences between the two groups in SWI-ASPECTS,SWI-DWI mismatch score and other indicators were compared.Spearman’s rank correlation test was performed to explore the correlation of ASITN/SIR scores with SWI-ASPECTS and SWI-DWI mismatch scores.Results:A total of 35 patients were enrolled.The SWI-DWI mismatch score in the good collateral group was significantly higher than that in the poor collateral group(7 vs 2;P<0.001).There was no significant difference in SWI-ASPECTS between the two groups(3 vs 3;P=0.297).SWI-DWI mismatch scores were positively correlated with ASITN/SIR scores(r=0.818,P<0.001).There was no significant correlation between SWI-ASPECTS and ASITN/SIR scores(r=-0.099,P=0.573).Conclusions:The range of PVS on SWI couldn’t well reflect the collateral status,while the range of SWI-DWI mismatch was significantly correlated with the leptomeningeal collateralization.In patients with acute anterior circulation stroke due to large vessel occlusion,the larger the SWI-DWI mismatch,the better the leptomeningeal collaterals.