Imaging of acute myocardial infarction and reperfusion.

During the last 20 years there has been a large amount of investigation designed to determine what is the best way of imaging acute myocardial infarction (AMI) using radiopharmaceuticals. 99mTc pyrophosphate is ideal for cases where the clinical diagnosis cannot be made but it is insensitive to detect subendocardial AMI and is taken up by reversibly-injured myocytes. Antimyosin antibody imaging is specific for AMI but 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. 18F fluorodeoxyglucose (FDG) is taken up by viable cells but likely by macrophages too, in the core of AMI. 99mTc glucarate has not been investigated in detail but this sugar analog is more accurate than FDG in AMI. 99mTc 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 microvascular injury and capillary plugging.