Analysis Of Imaging Characteristics Related To The Etiology Of Acute Ischemic Stroke Based On CT Perfusion

Part Ⅰ Thrombus morphology assessment and its relationship with the etiology of acute ischemic strokePurpose:Multi-segment thrombus(MST)sign has been observed on the site of large artery occlusion(LAO)in acute ischemic stroke(AIS)patients.This study aimed to assess its occurrence rate and relationship with stroke etiologies,and further to investigate its value in predicting recanalization and outcome after reperfusion therapy in patients with acute LAO.Methods:We included consecutive AIS patients who had acute LAO and underwent CT perfusion within 8 hours after stroke onset from May 2009 to July 2018.The MST sign was assessed on dynamic CT angiography derived from CT perfusion.The stroke etiologies were defined by the international Trial of Org 10172 in Acute Stroke Treatment(TOAST)criteria.Good outcome was defined as modified Rankin Score 0-2 at 90 days.Logistic regression analyses were used to investigate the association of MST sign with stroke etiologies and outcome.Results:A total of 431 LAO patients were enrolled,and MST sign was found in 221(51%)patients.According to the TOAST criteria,238(55.2%)patients were diagnosed as cardioembolism,89(20.6%)as large artery atherosclerosis,103(23.9%)as stroke of undetermined cause,and 1(0.2%)as stroke of other determined cause.Logistic analysis showed the presence of MST sign was significantly higher in patients with cardioembolism than those with large artery atherosclerosis(67.2%vs 20.2%;OR=7.501;95%CI:3.769-14.927;p<0.001).For determined etiologies,the sensitivity,specificity,positive and negative predictive value of the MST sign for predicting cardioembolism were 67.1%,78.9%,89.3%and 47.7%,respectively.Moreover,logistic regression analyses showed that MST sign was an independent predictor for both recanalization(OR=2.068;95%CI:1.274-3.357;p=0.003)and good outcome(OR=2.326;95%CI:1.376-3.933;p=0.002)after adjustment.Conclusion:The presence of MST sign on dynamic CTA specifically indicates LAO caused by embolism from cardiac source,and it is a good indicator for recanalization and good outcome after reperfusion therapy.Part Ⅱ Thrombus permeability assessment and its relationship with the etiology of acute ischemic strokePurpose:Thrombus permeability assessed on the conventional CTA was associated with neurological outcome in acute ischemic stroke(AIS)patients.We aimed to investigate whether dynamic CTA can improve the accuracy of thrombus permeability.Then we assessed its relationship with stroke etiologies and outcome.Methods:We reviewed consecutive AIS patients who had M1 segment of middle artery cerebral artery occlusion and underwent pretreatment CT perfusion from May 2009 to July 2018.Thrombus permeability,determined by thrombus attenuation increase(TAI),was assessed on 26-phase dynamic CTA derived from CT perfusion.TAImax was defined as the maximum TAI among phases,TAIpeak as TAI of peak arterial phase,TAIcon as TAI on phase 13(the median phase).The stroke etiologies were defined by the international Trial of Org 10172 in Acute Stroke Treatment(TOAST)criteria.Good outcome was defined as 90-day mRS score of ≤2.Logistic regression analyses were used to investigate the association of thrombus permeability assessed on dynamic CTA with stroke etiologies and outcome.Results:Totally 132 patients were enrolled in the final analysis.The median TAImax,TAIpeak and TAIcon were 29.0(14.7-49.7)HU,10.1(-2.1-28.6)HU and 7.2(-4.2-23.7)HU,respectively.Logistic regression analyses showed that TAImax,TAIpeak and TAIcon were not significantly associated with stroke etiology(all p>0.05),while TAImax was independently associated with good outcome(OR=1.020;95%CI:1.003-1.036;p=0.021).Conclusion:Thrombus permeability assessed on dynamic CTA did not show significant assocaition with stroke etiology,but could be a better predictor of outcome after reperfusion therapy than that assessed on conventional single-phase CTA.Part Ⅲ A Quantitative Collateral Assessment and its relationship with Etiology of Acute Ischemic StrokePurpose:To develop a new quantitative assessment of collateral perfusion on CT perfusion and to investigate its relationship with stroke etiologies,and further to evaluate its value in predicting outcome in patients with acute ischemic stroke(AIS).Methods:This retrospective study reviewed data from consecutive patients evaluated with AIS and occluded M1 segment of middle cerebral artery with or without internal carotid artery who underwent pretreatment CT perfusion from May 2009 to July 2018.The maximum cerebral blood flow(CBF)value of collateral vessels(cCBFmax)within the Sylvian fissure was calculated for each patient.The stroke etiologies were defined by the international Trial of Org 10172 in Acute Stroke Treatment(TOAST)criteria.Good outcome was defined as 90-day modified Rankin Scale 0-2.Logistic regression analyses were used to investigate the association of cCBFmax with stroke etiologies and outcome.Results:The final analysis included 296 patients(122[41.2%]females;median age,73 years;interquartile range,62-80 years).Logistic regression analysis showed that lower cCBFmax(ml/100g/min)was significantly associated with cardioembolism(OR=0.983;95%CI:0.972-0.995;p=0.004).And logistic regression analyses also found that higher cCBFmax was both an independent predictor for a lower risk of hemorrhagic transformation(OR,0.990;95%CI:0.981-0.998;p=0.012)after adjustment,and an independent predictor for better outcome(OR,1.015;95%CI:1.007-1.024;p<0.001)after adjustment,respectively.ROC analyses showed that good clinical outcome was associated with higher cCBFmax(AUC=0.739)than other three collateral status assessments,including modified Tan scale(AUC=0.619;p<0.001),Miteff scale(AUC=0.606;p<0.001)and rLMC score(AUC=0.648;p=0.006).Conclusion:The measurement of maximum cerebral blood flow(CBF)value of collateral vessels(cCBFmax)within Sylvian fissure is a feasible quantitative collateral assessment on CT perfusion and it is associated with stroke etiology and clinical outcome in AIS patients.