| Part ?:Value of Perfusion-Diffusion fusionimaging in assessment of ischemic penumbra in patients with acute ischemic strokeObjective:To assess the diagnostic value of ischemic penumbra(IP)selection using fusion images of perfusion-weighted imaging(PWI)and diffusion-weighted imaging(DWI),compared with volumetric-basedperfusion–diffusion mismatch(PDM)in patients with acute ischemic stroke(AIS),which was considered to be the “gold standard” of IP selection.Materials and methods: A total of 42 patients with a confirmed diagnosis of acute middle cerebral artery stroke<24 hours after symptom onset were included in this retrospective study.DWI images were overlaid onto time to peak(TTP)maps from PWI images to obtain fused images using 3D fusion software.The qualitative assessment of PDM was performed by The Alberta Stroke Program Early CT Score(ASPECTS).Quantitative volumewas obtained by semi-automated quantitative software.When the ratio of perfusion/diffusion lesion volume was >1.2,the patient was considered to have IP.The consistency ofPDM-ASPECTS scoresassessed by the two neuroradiologists using the fusion image were determined usingSpearman rank correlation coefficient.Areas under the receiver operating characteristic curve(AUC)was used to assess the diagnostic efficiency of PDM determined by fused images compared to volumetric-based PDM.Analysis of variance was used to assess any difference in time consumed for PDM assessment among the PDM-ASPECTS and volumetric-based PDM assessment methods.Results: The ASPECT scores of thepatients with PDM were higher than those without PDM.There was a high consistency between the PDM scores assessment by two neuroradiologists using fused images(kappa=0.969,p < 0.001).The PDM-ASPECT scores determined by two neuroradiologists also had a high diagnostic efficacy compared to volume-based PDM,the AUC was 0.885 and 0.877 respectively.No significant differences were noted in time consumed anddiagnostic reliability among inexperienced and experienced radiologists(p<0.05),but the time consumed of PDM-ASPECTS assessed by fusion images is lower than volume-based PDM.Conclusions:The fusion images of DWI and PWI provided information comparable to the information provided by volumetric-based PDM.It took less time and help the inexperienced radiologist to make accurate diagnosis,the PDM-ASPECTS assessment using fusion images might be an effective approach for IP selection in acute middle cerebral artery stroke.Part ?:The clinicalvalue of MHV in patients with acute ischemic strokeObjective: To retrospectively analysis the clinical value of multiple hypointense vessels(MHV),and the relationship between MHV and infarct volume,infarct site and cerebral perfusion status in patients with acute ischemic stroke(AIS).Materials and methods: A total of 43 patients with a confirmed diagnosis of acute middle cerebral artery stroke within 24 hours after symptom onset were included in this retrospective study,all patients underwent diffusion weighted imaging(DWI),Susceptibility weighted imaging(SWI)and perfusion weighted imaging(PWI).Cerebral blood flow(CBF),cerebral blood volume(CBV),time to peak(TTP)andmean transit time(MTT)were obtained by perfusion software.DWI images were overlaid onto TTP maps from PWI and minIP images from SWI to obtain PWI/DWI and SWI/DWI fused images using 3D fusion software.The qualitative assessment of PDM and SDM were carried out by the Alberta Stroke Program Early CT Score(ASPECTS).Quantitative volume was obtained using semi-automated quantitative software.MHV was classified into 4 prominence grades: 0 = no,1 = mild,2 = moderate,and 3 = distinct prominence.Areas under the receiver operating characteristic curve(AUC)was used to assess the diagnostic efficiency of SDM-ASPECTS determined by fused images compared to volumetric-based PDM.Inter-observer agreements were tested by using kappa statistics.The relationship between PDM-ASPECTS and SDM-ASPECTS,the grade of MHV and infact volume were determined using Spearman rank correlation coefficient.Results:In all of the 43 patients,31 patients were presented with MHV(72.09%,31/43)and 12 patients without MHV(27.91%,12/43),The incidence of MHV was significantly higher in AIS patients attributed to Middle cerebral artery Occlusion or stenosis of M1 or M2 segment than M3 segment(p = 0.02,p <0.05).The PDM-ASPECTS and SDM-ASPECTS in MHV(+)group were significantly higher than MHV(-)group(p<0.01).Both The SDM-ASPECTS and PDM-ASPECTS had a high diagnostic efficacy compared to volume-based PDM,the AUC were 0.845(95%CI,0.709-0.981)and 0.880(95%CI,0.757-1.000)respectively.The sensitivity and the specificity was 94.74% and 58.33% respectively,when 1 was used as the cut point of SDM-ASPECTS in PDM selected.The SDM-ASPECTS and the PDM-ASPECTS scoreshad a high consistency in the MHV1-3 grades(rho = 0.820,p<0.01).There was no significant correlation between MHV grade and infarct volume(rho = 0.163,p>0.05)in all patients,but MHV was negatively correlated with infarct volume in AIS patients attributed to middle cerebral artery occlusion or stenosis(rho =-0.538,p<0.05).There was no significant difference in rCBF,rCBV,rMTT and rTTP between the MHV(+)group and MHV(-)group.The MHV grades has no significant correlation with rCBF,rCBV,rMTT and rTTP(p>0.05).Conclusions:(1)MHV is more common in AIS patients attributed to Middle cerebral artery Occlusion or stenosis of M1 or M2 segment than M3 segment.(2)Both SDM-ASPECTS and PDM-ASPECTS can be effective in PDM assessment compared to volume-based PDM.(3)MHV was negatively correlated with infarct volume in AIS patients attributed to Middle cerebral artery occlusion or stenosis.Part ?:The value of collateral circulationclassification with dynamic MRI angiogrames in evaluating the short-term outcome in patients with AISObjective:To assessthe role of dynamic(4D)MRI angiograms in predicting short-term outcome in patients with AIS.Compare the relationship between FLAIR vascular hyperintensities(FVH)?multiple hypointenses vessels(MHV)on susceptibility-weighted imaging(SWI)and the classification ofcollateral circulation assessedin dynamic(4D)MRI angiograms derivedfrom perfusion raw data.Materials and methods:Thirty-six patients with MCA stroke were enrolled in this study.All patients underwent multimodality MRI examination within 4.5-24 hoursonset of stroke.The cerebral hemodynamic changes was assessed through the dynamic(4D)MRI angiograms derivedfrom perfusion raw data.The classification of the collateral circulation was assessed using a modification of the American Society of Interventional and Therapeutic Neuroradiology/Society ofInterventional Radiology(ASITN/SIR)Collateral Flow Grading System.The ratio of perfusion/ diffusionmismatch rate(ratio of Perfusion-Diffusion mismatch,rPDM)is defined as the misery perfusion volume/ infarct lesion on DWI.Classification thegrades of FVH and MHV separately.The improvement of national institutes of health stroke scale(NIHSS)score was used as a criterion of short-termclinical outcome.NIHSS score less than 2 or NIHSS score improved more than 4 was defined with a better progonosis15 days later,the other patients were defined with no significant effect.The AIS patients were divided into favorable and unfavorable outcome group according to the improvement of NIHSS score.The initial data,infarct volume,rPDM,FVH and MHV,the grade of collateral circulation and Logistic variables were analyzed.A multivariate Logistic regression analysis was used to identify variable influencing clinical outcomes.Inter-observer agreements were tested by using kappa statistics.Spearman correlation coefficients were used to analyze the consistency between the classification of collateral circulation,the infarct volume,rPDM volume,MHV and FVH.Results:(1)The classification of collateral circulation usedASITN/SIR based on 4D-MRA had a high consistency among the observers(kappa=0.726,p<0.001).(2)The collateral grade was negatively correlated withinitial infarct volume(rho=-0.615,p< 0.001),a significant correlation with rPDM(rho=0.533,p< 0.001),anda slight negative correlation with misery perfusion volume(rho=-0.326,,p< 0.01).(3)There was significant difference in infarct volume,rPDM and thecollateral circulation classification between favorable and unfavorable outcome group(p< 0.05),the infarct size was smaller,the rPDM was higher,and the collateral circulation was better in favorable outcome group.(4)The collateral circulation classification based on 4D-MRA was a independent predictor of clinical prognosis in AIS patients with favorable outcome(OR=2.781,95%CI=0.341-1.835,p<0.05).There was a fair correlation betweenFVH(rho=0.338,p< 0.001)and no significant correlation between MHV classification(rho=0.149,p> 0.05).Conclusion: 4D-MRA is a reliable method for analyzing the cerebral hemodynamic changes and collateral circulation classification,with a high consistency between observers.The classification ofcollateral circulation assessedin dynamic(4D)angiograms derivedfrom perfusion raw data is a good independent predictor of clinical outcome in AIS. |
PDF Full Text Request