Objective To investigate the relationship between carotid artery plaque of different characteristic and matrix metalloproteinase-9(MMP-9) in patients with acute cerebral infarction, To explore the value of carotid atherosclerotic plaque stability and serum MMP-9 level in acute cerebral infarction. Methods There were 113 patients with acute cerebral infarction(ACl group) and31 cases of healthy persons. All subjects were detected the characteristic by carotid artery ultra-sonography. ACl group was divided int...