| Objective: To study the value of diagnosis in acute ischemic stroke by useing three dimensional-Artery Spin Labeling(3D ASL),To investigate the changes of cerebral blood flow in patients with acute ischemic stroke,and to assess the diagnosis value of3 D ASL by comparing with Diffusion Weighted Imaging(DWI)and magnetic resonance angiography,(MRA).Materials and methods:19 patients without cerebrovascular disease,brain tumor or other diseases affecting cerebral blood flow were selected as control group.Among them,11 were male and 8 were female,and the average age was 66 years.19 patients with acute cerebral infarction were selected as the experimental subjects.Among them,11 were male and 8 were female,and the average age was 66 years.Diagnosis and staging of acute ischemic stroke based on Chinese acute ischemic stroke guidelines(2014Edition).Ischemic stroke within 2 weeks of the onset of the disease is classified as acute phase.According to the cerebral infarction area,the lesions were divided into large lesions,secondary lesions,small lesions and lacunar infarction lesions.This experiment involves the United States signa HDxt 1.5T MR GE magnetic resonance scanner.The scan sequences included cross section FSE T2 WI,cross section FSE T1 WI,sagittal section FSE T1 WI,3D ASL,cross section DWI and 3D-TOF.The total length of the scan is about 20 min.Using aw4.6 workstation fuctool software package for postprocessing of imaging.For control group,Blood flow cerebral(CBF)images were analyzed with the conventional scan sequence.Draw diameter about 10 mm circular area of interest in the brain stem,dorsal thalamus,lenticular nucleus,gray and white matter of frontal lobe andparietal lobe.With the center line of the brain as the axis of symmetry,to obtain a mirror ROIs on the other side.Then,regional cerebral blood flow(r CBF)values generated in different reigns of the brain.Analyze the distribution of cerebral blood flow in different parts of the brain to judge the reliability of 3D ASL.Combined with routine MRI sequences,DWI and CBF images of the experimental group were compared to analyze the characteristics of CBF image in patients with acute ischemic stroke and to investigate the detection of acute cerebral infarction and cerebral ischemia by 3D ASL relative to DWI.Using postprocessing software,to draw the infarct area of low perfusion and get the r CBF value,and to compare the r CBF value of the contralateral normal perfusion image area to evaluate the changes of cerebral blood flow in the infarct and ischemic area.Manually mark the area of high signal infarct area in DWI images,compare the range of DWI images with CBF images of the cerebral infarction area,and determine the relationship between the DWI image and CBF image.To analyze the relationship between the low perfusion area in CBF image and the intracranial artery stenosis and occlusion in combination with the intracranial arterial vascular status in MRA.Using SPSS 21 software to make statistical analysis,and mean was expressd in the form of `x±s.Depending on the type of data,measurement data use two independent samples t-test,paired samples t-test,ANOVA and Mann-Witney U test,and tables from use the Fisher exact test.The sensitivity and specificity of the test methods were analyzed by using the receiver operating characteristic curve.If P<0.05 there is statistical difference.Results1.In the control group,19 volunteers has no positive lesions in conventional MRI images,DWI and CBF images,and 6 has intracranial arterial stenosis.In the control group,the average r CBF value was 48.6±7.4 ml/100g·100g.The r CBF values of the right and left dorsal thalamus were 46.1±5.8 and 45.4±6.6 ml/100g·min,respectively;The r CBF values of the right side of the putamen and the left side were49.4±7 and 50.3±8.6 ml/100g·min,respectively;The right and left frontal lobe white matter r CBF values were 25.1±4 and 26.1±4.3 ml/100g·min,respectively;The right and left frontal cortex r CBF were 67.1±8.9 and 67.9±8.1 ml/100g·min,respectively;The gray matter and r CBF value of the white matter on the right side and left side were 24.4±44.4 and 2439±5.2 ml/100g·min,respectively;The gray matter and r CBF value of the white matter on the right side and left side were 62.7±7.9 and 62±6.7 ml/100g·min,respectively.There were no statistical differences in r CBF of each symmetrical anatomical region.Within the grope of gray matter and white matter,there was no statistical difference in r CBF value.2.In 19 patients with acute cerebral infarction,there is a total of 3 ischemic lesions and 31 infarction lesion;In 31 infarcts,16 was positive in CBF with positive rate of51.6%;the positive rate of lacunar infarction in CBF was 25%,the positive rate of non lacunar infarction in CBF was 80%.3 ischemic lesions were negative for DWI but CBF showed low perfusion.ADC and r CBF values of 31 infarction were analyzed by ROC.The sensitivity of ADC was close to 100%,the specificity 97%,and the area under the ROC curve was0.986.The sensitivity of CBF was 70.6%,the specificity 73.5%,and the area under the ROC curve 0.734;P values were less than 0.05.3.In the experimental group,the difference of r CBF between the abnormal perfusion areas and the normal perfusion area was-12.3 + 19.4.The paired t test was t=-3.522 and P<0.05.After comparing the means of two groups,it was concluded that the r CBF of abnormal perfusion area was lower than that of the image area.4.5 of 19 cases of acute cerebral infarction appera luxury perfusion area.T test was performed on the r CBF of the high perfusion area and the mirror image region,and the t=3.064,P>0.05.5.Within 34 ischemia and infarction lesions,there were 17 lesions in the presence of DWI,CBF mismatch phenomenon.Paired t test was performed on the lesion area obtained from the two kinds of images and get t=-2.684,P<0.05,which means that the low perfusion area obtained from CBF images is larger than the area of DWI high signalarea,and there may be penumbra.6.19 cases of stroke patients,1 case showed unilateral internal carotid artery occlusion,1 case cerebral artery occlusion,7 cases single solitary or multiple intracranial vascular stenosis,four cases multiple intracranial sclerosis.Using Fisher exact test to analyze the correlation between the MRA and CBF results in the stroke group,P>0.05 was obtained.It is considered that there is a correlation between the two results.Conclusion:1.3D ASL can accurately reflect the distribution of cerebral blood flow.In resting state,the distribution of cerebral blood flow is symmetrical,and the r CBF in gray matter is higher than the white matter area.2.D ASL can detect the decrease of r CBF value in patients with acute ischemic stroke,and realize the visualization of cerebral blood flow.3.The sensitivity and specificity of 3D ASL in the diagnosis of acute ischemic stroke were weaker than DWI,and the positive rate of ASL was increased with the increase of ischemic stroke area.At the same time,there is a certain correlation between the results of ASL 3D and MRA.4.ASL can detect the decreased r CBF area which can not show in the T1 WI,T2WI and DWI,and provide more information about the brain tissue ischemia to clinical doctors. |
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