Clinicians who treat patients with coronary artery disease (CAD) are faced with the challenge of making a therapeutic decision to recommend revascularization or medical treatment. A conflict often exists making that decision as various methods and metrics assessing myocardial ischemia are discordant with each other. The purpose of this lecture is to provide insight into the measurement of myocardial blood flow (MBF) and its interpretation. The presentation will provide clarity concerning various metrics of MBF, the relationship between the metrics and how these metrics may be discordant with each other and with angiographic findings. The concept of coronary flow capacity (CFC) will be presented and its relevance and impact on clinical practice and patient care will be discussed. Clinicians who participate in this program will gain an appreciation for the use of positron emission tomography (PET) scanning with CFC to help identify patients who will benefit from revascularization.