How does an FDG PET scan of the heart help to evaluate for myocardial viability?
The primary energy substrate of the myocardium is free fatty acids rather than glucose. During ischemia, however, there is a switch in the myocardium to use of glucose. If there is decreased perfusion but preserved FDG uptake (i.e., metabolism), then that area of the myocardium is considered to be viable. If there is decreased perfusion and metabolism, then that area of the myocardium is considered to be a scar