Purpose of Review <p>Measurement of absolute myocardial blood flow (MBF) improves on relative myocardial perfusion imaging (MPI). It can more accurately identify multi-vessel disease and aid in the assessment of microvascular disease. It also provides independent prognostic information for risk stratification. The advent of solid-state stationary SPECT systems has led to renewed interest in the use of SPECT to measure absolute myocardial blood flow. The large utilization of SPECT for MPI means that there is a large potential impact from the clinical implementation of SPECT MBF. In this paper we review the evidence validating SPECT MBF measurements and discuss its limitations and some directions for development that could further improve its performance.</p> Recent Findings <p>SPECT MBF correlates well with angiographic measurements of coronary artery disease and with MBF values from PET imaging. A current limitation is its repeatability which might be improved by new tracers with increased extraction fraction, more advanced reconstruction algorithms, and increased automation in analysis software. Study duration could be reduced through careful application of rapid acquisition protocols, and larger studies are needed to demonstrate potential benefit of SPECT MBF measurements.</p> Summary <p>SPECT MBF is a promising technology that is feasible to use clinically. Several research directions are possible to enhance precision and reduce the time needed for study acquisition and processing.</p>