The Preliminary Study Of APT Imaging In Acute Cerebral Infarction

OBJECTIVE:We aim to observe the signal performance of amide proton transfer imaging appearing in acute ischemic stroke,and to investigate the feasibility and clinical application of its various evaluation parameters including APTR,MTRasym.We will analyze the changes of pH environment in different perfusion regions of acute ischemic stroke to provide the basis for further study in Physiological mechanisms of the ischemic stroke.Subjects and Methods:Twenty-five patients with acute ischemic stroke were selected and scanned by conventional MRI,DWI,APT,DSC-PWI.According to whether DWI and PWI anomaly area mismatch or not,the patients were divided into mismatch group and match group.The MRIcron software was used to obtain APTR,MTRasym parameters in the infarct core area,infarct peripheral area,contralateral normal brain parenchyma area.The data were counted by SPSS 22.0 software package.The Wilcoxon paired sample test was used to compare the difference of parameter values between the infarct core area and the contralateral normal brain parenchymal area;the Friedman correlation sample test was used to compare the infarct core area,the infarct peripheral area,and the contralateral normal brain parenchymal area in each group and pairwise comparisons between different regions,P<0.05 significant.Results:(1)The values of APTR and MTRasym in the infarct core area were significantly lower than those in the contralateral normal brain parenchyma(Z=-4.373,P<0.001;Z=-2.381,P=0.017).(2)There were both significant differences in APTR parameter between infarct core area and contralateral normal brain parenchyma area(χ~2=15.000,P<0.001),infarct peripheral area and contralateral normal brain parenchyma area(χ~2=8.067,P=0.005)in DWI/PWI mismatch group,while there was no significant difference between infarct core area and infarct peripheral area.There were both significant differences in APTR parameter between infarct core area and contralateral normal brain parenchyma area(χ~2=10.000,P=0.002),infarct core area and infarct peripheral area(χ~2=10.000,P=0.002)in DWI/PWI match group,while there was no significant difference between infarct peripheral area and contralateral normal brain parenchyma area.(3)The APTR value were statistically different between the infarct core and the contralateral normal brain parenchymal area in both the DWI/PWI mismatch group and the match group.The values of MTRasym only showed significant differences(χ~2=6.400,P=0.011)between infarct core area and contralateral normal brain parenchyma area in DWI/PWI match group.Conclusions:(1)The APT imaging of acute ischemic stroke can display abnormal signal change in the acute infarct lesion and distinguish normal brain tissue and acid-toxic brain tissue and may provide complement metabolic information for local metabolic changes in ischemic stroke.(2)In infarct peripheral area,the pH in different blood perfusion areas showed inconsistent performance.In the DWI/PWI mismatch group,there was no difference in APTR value between the infarct peripheral area and the infarct core area and a difference with contralateral normal brain parenchyma area,which indicated that there was acidosis in the infarct peripheral area due to low perfusion;In the DWI/PWI match group,there was a difference in APTR value in the infarct peripheral area with the infarct core area and no difference with the contralateral normal brain parenchyma area,indicating that there was no acidosis in the infarct peripheral area with normal perfusion.(3)APTR was more sensitive than MTRasym in revealing acidosis changes in both the infarct core area and DWI/PWI mismatch area.