Myocardial flow reserve (MFR) with positron emission tomography (PET)/computed tomography (CT): clinical impact in diagnosis and prognosis

In recent years, radionuclide myocardial perfusion imaging (MPI) using positron emission tomography/computed tomography (PET/CT) has emerged as a robust tool for the diagnosis, risk stratification and management of patients with known or established coronary artery disease (CAD). Cardiac PET/CT imaging affords key advantages compared to single photon emission computed tomography (SPECT) that encompass: (I) improved diagnostic accuracy; (II) decreased radiation exposure due to the utilization of short-lived radiopharmaceuticals, and importantly; (III) the ability to quantify noninvasively myocardial blood flow (MBF) in absolute terms, that is in ml per minute per gram of tissue. Quantitative approaches that measure MBF with PET can facilitate the diagnosis of multivessel CAD and offer the opportunity to monitor responses to lifestyle and/or risk factor modification and to therapeutic interventions. The aim of this review is to focus on the potential clinical utility of MBF and will discuss: (I) basics aspects of PET clinical perfusion tracers and flow quantification parameters; (II) limitations of relative MPI, (III) summarize a classification of diseases where flow quantification may be of use; (IV) specifically, review data on the diagnosis and prognostic value of flow quantification.