Evaluating The Ischemic Penumbra By MR ASL Perfusion-comparing With CTP

Objective:To evaluate the value of magnetic resonance arterial spin labeling(ASL)perfusion imaging and CT perfusion(CTP) imaging in acute ischemic stroke and ischemic penumbra.Methods:Choosing 20 patients with ischemic stroke within 24 hours of onset time,each of them underwent MR examination of head by using SIEMENS 3.0T MRI scanner.Including conventional T1 WI,T2WI,T2 FLAIR,DWI sequences and ASL sequences.Then introduced the ASL sequence into the post-processing workstation,and the color perfusion map was obtained.Then the patient take head CT examination after completing MR examination,including no-contrast CT scan and CTP examination,the color perfusion map was obtained after post-processing.Compare ASL and CTP map whether there are differences perfusion status,results using Paired data chi square test.Maximum level of lesion showed on DWI is choosed as the standard level,choose the contralateral hemisphere mirror for reference,on the ASL map and CTP map outlined abnormal perfusion region as region of interest,compare ASL map and MTT map about abnormal perfusion region size,the results using independent sample t test.ASL-DWI and CBF-CBV,TTP-CBV mismatch can determine whether ischemic penumbra exist,judgment standard:abnormal perfusion area does not match infarction district reached 20%,cases with ischemic penumbra use Pearson correlation analysis.On the CTP map,measure the center,edge of abnormal perfusion region and the mirror region,get the perfusion parameters about CBF,CBV,MTT, the results using independent sample t test.Results: among 20 cases,18 cases of two methods showed the same perfusion status(ASL and CTP all low perfusion),2 cases give different results(CTP low perfusion,ASL no abnormal perfusion),there is no statistically significant difference between the two methods.The size of abnormal perfusion in the largest lesion level,which was showed in the ASL and CTP-MTT maps,can be obtained,there is no statistically significant difference between the two methods.With 10 cases of ischemic penumbra,IP1 = ASL-DWI and IP2 = CBF –CBV,IP3= TTP –CBV was significantly positively related. In the center of the perfusion defect area,CBF,CBV value is lower than the edge area,MTT value is higher than the edge area,dfference was statistically significant.Conclusions:The magnetic resonance ASL technique and CTP have good consistency in the evaluation of cerebral infarction. A significant positive correlation was showed between the models of ASL-DWI mismatch and CBF-CBV,TTP-CBV mismatch in the evaluation of cerebral ischemic penumbra;There are significant differences in the perfusion parameters between the center perfusion defect area and the edge.