IMAGING OF ACUTE MYOCARDIAL-INFARCTION AND REPERFUSION

During the last 20 years there has been a large amount of investigatio n designed to determine what is the best way of imaging acute myocardi al infarction (AMI) using radiopharmaceuticals. Tc-99m pyrophosphate i s ideal for cases where the clinical diagnosis cannot be made but it i s insensitive to detect subendocardial AMI and is taken up by reversib ly-injured myocytes. Antimyosin antibody imaging is specific for AMI b ut it is flow-dependent at low myocardial flows and it distributes in a nonuniform way in reperfused infarcts requiring high nuclear imaging (SPECT or PET) spatial resolution for proper measurement. F-18 fluoro deoxyglucose (FDG) is taken up by viable cells but likely by macrophag es too, in the core of AMI. Tc-99m glucarate has not been investigated in detail but this sugar analog is more accurate than FDG in AMI. Te- 99m sestamibi has been extensively used for AMI measurement but SPECT quantitation of transmural infarcts has not been achieved. Unresolved issue is imaging of AMI during reperfusion where there is widespread m icrovascular injury and capillary plugging.