Myocardial perfusion by positron emission tomography (PET) is a well-established and validated tool for assessing myocardial perfusion and quantifying absolute myocardial blood flow. As such, cardiac PET serves as an ideal technology for quantifying changes in flow after revascularization procedures. Noninvasive myocardial perfusion imaging by positron emission tomography (PET) combines high spatial resolution (down to secondary or tertiary coronary branches) with quantitative measures of rest and stress myocardial perfusion in absolute units to compute absolute coronary flow reserve (CFR). Quantitative myocardial perfusion by PET has an extensive and technically robust literature, with over 250 papers including almost 15,000 subjects in the past 25 years.