The Importance of Time-of-Flight Reconstruction and Point Spread Modeling in the Measurement of Myocardial Blood Flow Parameters

Purpose of Review Absolute quantitation of myocardial blood flow has been recognized as one of the most important advances in nuclear cardiology. The addition of absolute myocardial blood flow quantitation has had a significant impact on the determination of normalcy, artifact/defect differentiation, and the true extent of coronary artery disease in patients with known or suspected coronary disease. Time-of-flight reconstruction and point spread function modeling of the potential to greatly improve resolution and signal to background. This combined with absolute blood flow measurements could improve the reliability of regional blood flow estimates and overall image quality. Recent Findings Recent publications have demonstrated that time-of-flight reconstruction can have an impact on the amount of spillover between the blood pool ROI and the myocardial regions. This may necessitate changes to kinetic models; however, these changes if implemented correctly may result in improved accuracy and reproducibility of blood flow estimates. This may also have the benefit of assessing blood flow in the microvasculature using newer F-18 labeled blood flow tracers. Summary Time of flight and point spread function modeling represent significant improvements in the accuracy and quality of reconstructed myocardial perfusion PET images. This may also have significant implications for the reliability of blood flow estimates. To achieve these benefits, attention must be given to blood flow models to ensure that they have been correctly optimized for the scanner-specific time-of-flight reconstruction properties.