Animal Experimental Study on Changes of MRI Signs During Myocardial Infarction Process

Objective To evaluate the changes of MRI signs during the myocardial infarction.Methods Left anterior descending (LAD) and Left cricumflex (LCx) coronary artery were ligated simultaneously in rabbits.Before the operation,at 30 minutes,1 hour,2 hours,4 hours,8 hours,1 day,3 days,1 week,2 weeks,and 4 weeks after ligation,imagings on T1,PD,T2,enhancement,cine-MRI were obtained respectively,to measure the intensity and thickness in different regions of left ventricular wall.Results At 30 minutes after ligation,the ischemic local wall of left ventricle became thinner,more in contractile phase,and became worse gradually.At 1 hour after ligation,hyperintensity on PDWI and T2WI in region of infarction was found,and became higher gradually,then the signal descended in 1 week after ligation,hypointensity in 4 weeks; hypointensity on T1WI was found in 4 weeks in region of infarction; In acute myocardial infarction,normal myocardium was enhanced in 5 minutes after injection, ring enhancement could be found in the marginal region of infarction in 15-20 minutes,centre of infarction was enhanced in 30 minutes.Conclusion MRI can find the myocardial ischemia of large area at early stage and can comfirm the stages of myocardial infarction.