SPECT images collected after the administration of [99mTc][TcN-MPO] and [99mTc]Tc-Sestamibi in canines with acute myocardial infarction indicated an early visualization (30 min after injection) of the perfusion defect with [99mTc][TcN-MPO], but not with [99mTc]Tc-Sestamibi. This evidence concerns the gene MPO and myocardial infarction.