| Part 1 Pre-operative Cerebral Small Vessel Disease on MR Imaging Is Associated With Cerebral Hyperperfusion After Carotid EndarterectomyObjectives:To determine whether preoperative cerebral small vessel disease is associated with cerebral hyperperfusion after carotid endarterectomy(CEA).Methods:Seventy-four patients(mean age of 65.8±7.4 years and 75.7%male)undergoing CEA for carotid stenosis were investigated using brain MRI within 2 weeks before surgery and 1 week after surgery.The grade or the number of four cerebral small vessel disease markers(white matter hyperintensities,lacunes,perivascular spaces,and cerebral microbleeds)were evaluated based on preoperative MRI.Cerebral blood flow(CBF)was measured on preoperative and postoperative arterial spin labeling MR images,and cerebral blood flow ratio(rCBF)map was obtained by dividing postoperative CBF with preoperative CBF maps.Hyperperfusion regions with rCBF>2 were extracted and weighted with rCBF to calculate hyperperfusion index.According to the distribution of hyperperfusion index,patients were divided into hyperperfusion and non-hyperperfusion groups.The association between cerebral small vessel disease markers and cerebral hyperperfusion were assessed by using multivariate logistic regression analysis receiver-operating characteristic curve analysis.Results:Cerebral hyperperfusion after CEA was observed in 14 patients(18.92%).Logistic regression analysis revealed that Fazekas score of white matter hyperintensities(OR 2.78,95%CI[1.46,5.28],p=0.002)and number of lacunes(OR 1.46,95%CI[1.04,2.04],p=0.029)were independently associated with postoperative cerebral hyperperfusion.Fazekas score of white matter hyperintensities≥3 points(area under the curve[AUC]=0.78)and number of lacunes≥ 2(AUC=0.67)were the optimal cutoff values for predicting cerebral hyperperfusion.Conclusion:In patients with carotid stenosis,white matter hyperintensities and lacunes adversely affect cerebral hyperperfusion after CEA.Part 2 Arterial Transit Artifacts on Arterial Spin Labeling MRI Can Predict Cerebral Hyperperfusion After Carotid EndarterectomyObjectives:To investigate whether preoperative arterial spin labelling(ASL)MRI can predict cerebral hyperperfusion after carotid endarterectomy(CEA)in patients with carotid stenosis.Methods:Consecutive patients with carotid stenosis who underwent CEA between May 2015 and July 2021 were included.MRI scans were performed within 2 weeks before CEA and 1 week after CEA.In 10 regions of interest corresponding to ASPECTS methodology,preoperative ASL images were scored based on the presence of arterial transit artifacts(ATAs)as follows:0,no or minimal ASL signal;1,low/moderate ASL signal with ATA;2,high ASL signal with ATA;and 3,normal perfusion without ATA.Cerebral hyperperfusion was defined as an increase in cerebral blood flow>100%compared with baseline.Degree of stenosis,primary and secondary collaterals were evaluated to correlate with ASL score.Logistic regression and receiver operating characteristic curves analysis were performed to assess the predictive ability of ASL score for cerebral hyperperfusion.Results:Of 86 patients included(mean age of 65.3±7.1 years and 75.6%male),cerebral hyperperfusion was presented in 17(19.8%)patients.Carotid near-occlusion(p=0.001),opening of posterior communicating arteries with incomplete anterior semicircle(p=0.001)and leptomeningeal collaterals(p<0.001)were associated with lower ASL scores.Preoperative ASL score was an independent predictor of cerebral hyperperfusion(OR 0.48,95%CI[0.33-0.71],p<0.001)with the optimal cutoff value of 25 points(AUC=0.98,94.1%sensitivity,88.4%specificity).Conclusion:Based on the presence of ATAs,ASL can non-invasively predict cerebral hyperperfusion after CEA in patients with carotid stenosis.Part 3 Multi-delay Arterial Spin Labeling MR Perfusion Map for the Prediction of Cerebral Hyperperfusion After Carotid EndarterectomyObjectives:Multi-delay arterial spin labeling(ASL)generates time-resolved perfusion maps.The purpose of this study was to determine whether imaging markers derived from multi-delay ASL MRI can predict cerebral hyperperfusion after carotid endarterectomy(CEA).Methods:From July 2020 to February 2022,79 patients(mean age of 65 ± 7.6 years and 79.7%male)who underwent CEA for carotid stenosis were prospectively included for analysis.MRI scans were completed within 2 weeks before surgery and 7 days after surgery.Pseudo-continuous ASL with 3 post-labeling delays of 1.0,1.57 and 2.46s was performed.Cerebral perfusion pressure,antegrade and collateral flow were scored on a four-grade ordinal scale based on preoperative multi-delay ASL perfusion maps.Simultaneously,quantitative hemodynamic parameters including cerebral blood flow(CBF),arterial transit time(ATT),relative CBF(rCBF)and relative ATT(rATT;ipsilateral/contralateral values)were calculated.On the CBF ratio map obtained through dividing postoperative by preoperative CBF map,regions of interest were placed covering ipsilateral middle cerebral artery territory.Cerebral hyperperfusion was defined as a CBF ratio>2.Results:Cerebral hyperperfusion was observed in 15(19%)patients.Higher blood pressure(OR 1.08,95%CI[1.02,1.14],p=0.004)and carotid near-occlusion(OR 7.31,95%CI[4.75,293.63],p=0.034)were clinical risk factors for hyperperfusion.Poor ASL perfusion score(OR 37.33,95%CI[4.75,293.63],p=0,001),decreased CBF(OR 0.74,95%CI[0.62,0.88],P=0.001),prolonged ATT(OR 1.02,95%CI[1.01,1.03],p<0.001),lower rCBF(OR 0.91,95%CI[0.85,0.97],p=0.004)and higher rATT(OR 1.12,95%CI[1.04,1.20],p=0.003)were independent imaging predictors of hyperperfusion.Combined with ASL perfusion score,CBF and ATT,the predictive ability was significantly higher than using blood pressure and near-occlusion alone(AUC:0.98,95%CI[0.92,0.998]vs 0.78 95%CI[0.68,0.87],p=0.006).Conclusion:Multi-delay ASL can accurately predict cerebral hyperperfusion after CEA with high sensitivity and specificity.Part 4 Territory Arterial Spin Labeling MRI for the Prediction of Cerebral Hyperperfusion After Endarterectomy in Patients With Carotid Near-occlusionObjectives:To explore whether imaging markers derived from territory arterial spin labeling(tASL)MRI can predict cerebral hyperperfusion after carotid endarterectomy(CEA)in patients with carotid near-occlusion.Methods:From May 2015 to May 2022,patients diagnosed with carotid near-occlusion and preparing to receive CEA were prospectively included.MR scans were performed 2 weeks before surgery and 7 days after surgery.On the preoperative tASL images,flow territory of ipsilateral internal carotid artery(ICA)(normal,partial reduction[<50%],significant reduction[>50%]),compensation from contralateral ICA and vertebrobasilar artery(no compensation,partial compensation[<50%],significant compensation[>50%]),postoperative normalization of ICA flow territory was visually assessed.In addition,ipsilateral cerebral blood flow(ipCBF),contralateral CBF(conCBF),ipsilateral ICA perfusion volume ratio(ripPV),contralateral ICA perfusion volume ratio(rconPV)and total perfusion volume ratio(rtPV)were quantified.Cerebral hyperperfusion was defined as an increase of CBF more than 100%compared with baseline.Results:Of 34 patients(mean age of 64.8±7.5 years and 79.4%male),16(47.06%)had cerebral hyperperfusion.Incomplete circle of Willis(43.8%vs 88.8%,p=0.004),significantly reduced flow territory of ipsilateral ICA(62.5%vs 16.7%,p=0.013),significant compensation from contralateral ICA(43.8%vs 5.6%,p=0.031)and postoperative normalization of ICA flow territory(85.7%vs 43.8%,p=0.045)were associated with cerebral hyperperfusion.In terms of quantitative parameters,preoperative lower ipCBF(14.05 ± 6.23 ml/100g/min vs 17.76 ± 2.90 ml/100g/min,p=0.041),lower conCBF(22.88± 8.64 ml/100g/min vs 27.93 ±4.66 ml/100g/min,p=0.049)and smaller rtPV(98.11%± 13.55%vs 108.66%±12.28%,p=0.023)were associated with cerebral hyperperfusion.Conclusion:Preoperative tASL MR imaging is an useful tool for the prediction of cerebral hyperperfusion after CEA in patients with carotid near-occlusion. |
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