[PET evaluations of ischemic heart disease showing transient ST-T elevation: report of two cases]

Positron emission tomography (PET) was performed in two patients who exhibited transient ST-T elevation during their attack. The myocardial blood flow (MBF) and tissue fraction were quantitatively measured using dynamic PET and O-15 water. Myocardial exogenous glucose utilization was also determined by PET and F-18 fluoro-deoxyglucose (FDG). The FDG uptake index (FUI), obtained by dividing the total FDG count in the region of interest by the total amount of FDG, was used. These values were free from the partial volume effect because of the correction of the tissue fraction. Case 1: A 61-year-old woman was admitted to our hospital because of ST-T elevation on her ECG during her abdominal surgery. Her myocardiogenic enzymes were elevated. The emergency coronary angiogram showed no pathological coronary artery stenosis or occlusion, but the levogram showed abnormal wall motion. About one month later, the repeat coronary angiogram showed restoration to normal wall motion. In a PET study, myocardial blood flow and FUI were increased above the normal range. Case 2: A 65-year-old man was admitted to our hospital because of ST-T elevation on his ECG during chest oppression. In a PET study one month after the last chest pain, myocardial blood flow was normal, but there was a high uptake of FDG in the transient ischemic area. The coronary angiogram revealed no pathological lesions. It was suggested that the high uptake of FDG is related to a previous ischemic event; not to a present ischemic state. It is thought that these two cases exemplify so-called "myocardial stunning".