Non-invasive measurement of coronary flow reserve: uniqueness of radionuclide methods and alternative techniques.

Over the last several decades, radionuclide Myocardial Perfusion Imaging (MPI) has been a mainstay for the evaluation of coronary artery disease (CAD), based on the assumption that a detailed knowledge of stenosis localization and severity is not sufficient for clinical decision making. Furthermore, radionuclide MPI diagnostic accuracy has been implemented by the assessment of Coronary Flow Reserve (CFR) and Myocardial Blood Flow (MBF), as quantitative indexes of stenosis severity and surrogates of total ischaemic burden. Several considerations indicate that these measurement actually improve description of coronary physiology with respect to conventional qualitative image analysis. However, several alternative approaches have been optimized and increasingly proposed to achieve this task in the clinical setting. The aim of the present narrative review is to discuss strengths and weaknesses of the various cardiac modalities proposed to define CFR and MBF in the era of multi-modality imaging.