Parametric Imaging With Dynamic PET for Oncological Applications: Protocols, Interpretation, Current Applications and Limitations for Clinical Use

Nuclear medicine imaging modalities, and in particular positron emission tomography (PET), provide functional images that demonstrate the mean radioactivity distribution at a defined point in time. With the help of mathematical model's, it is possible to depict isolated parameters of the radiotracers' pharmacokinetics and to visualize them. These so called parametric images add a new dimension to the existing conventional PET images and provide more detailed information about the tracer distribution over time and space. Prerequisite for the calculation of parametric images, which reflect specific pharmacokinetic parameters, is the dynamic PET (dPET) data acquisition. Hitherto, PET parametric imaging has mainly found use for research purposes. However, it has not been yet implemented into clinical routine, since it is more time-consuming, it requires a complicated analysis and still lacks a clear benefit over conventional PET imaging. However, the recent introduction of new PET-CT scanners with an ultralong field of view, which allow a faster data acquisition and are associated with higher sensitivity, as well as the development of more sophisticated evaluation software packages will probably lead to a renaissance of dPET and parametric maps even of the whole body. The implementation of dPET imaging in daily routine with appropriate acquisition protocols, as well as the calculation, interpretation and potential clinical applications of parametric images will be discussed in this review article. Semin Nucl Med 52:312-329 (c) 2021 Published by Elsevier Inc.

Automated summary

Nuclear medicine imaging modalities, particularly positron emission tomography (PET), can provide functional images that show the distribution of radioactivity at a specific time point. By using mathematical models, specific parameters of radiotracer pharmacokinetics can be depicted and visualized. These parametric images offer additional information about the distribution of the tracer over time and space compared to conventional PET images. Although PET parametric imaging has been mainly used for research purposes, advancements in PET-CT scanners and evaluation software may lead to its implementation in clinical practice.